液压系统液压传动和气压传动中英文对照外文翻译文献
液压系统液压传动和气压传动毕业论文中英文资料对照外文翻译文献综述
中英文资料对照外文翻译文献综述液压系统液压传动和气压传动称为流体传动，是根据17世纪帕斯卡提出的液体静压力传动原理而发展起来的一门新兴技术，1795年英国约瑟夫•布拉曼(Joseph Braman,1749-1814)，在伦敦用水作为工作介质，以水压机的形式将其应用于工业上，诞生了世界上第一台水压机。
1905年将工作介质水改为油，又进一步得到改善。
第一次世界大战(1914-1918)后液压传动广泛应用，特别是1920年以后，发展更为迅速。
液压元件大约在 19 世纪末 20 世纪初的20年间，才开始进入正规的工业生产阶段。
1925 年维克斯(F.Vikers)发明了压力平衡式叶片泵,为近代液压元件工业或液压传动的逐步建立奠定了基础。
20 世纪初康斯坦丁•尼斯克(G•Constantimsco)对能量波动传递所进行的理论及实际研究;1910年对液力传动(液力联轴节、液力变矩器等)方面的贡献，使这两方面领域得到了发展。
第二次世界大战(1941-1945)期间,在美国机床中有30%应用了液压传动。
应该指出,日本液压传动的发展较欧美等国家晚了近 20 多年。
在 1955 年前后 , 日本迅速发展液压传动,1956 年成立了“液压工业会”。
近20～30 年间，日本液压传动发展之快，居世界领先地位。
液压传动有许多突出的优点，因此它的应用非常广泛，如一般工业用的塑料加工机械、压力机械、机床等；行走机械中的工程机械、建筑机械、农业机械、汽车等；钢铁工业用的冶金机械、提升装置、轧辊调整装置等；土木水利工程用的防洪闸门及堤坝装置、河床升降装置、桥梁操纵机构等；发电厂涡轮机调速装置、核发电厂等等；船舶用的甲板起重机械（绞车）、船头门、舱壁阀、船尾推进器等；特殊技术用的巨型天线控制装置、测量浮标、升降旋转舞台等；军事工业用的火炮操纵装置、船舶减摇装置、飞行器仿真、飞机起落架的收放装置和方向舵控制装置等。
一个完整的液压系统由五个部分组成，即动力元件、执行元件、控制元件、辅助元件和液压油。
液压传动系统外文文献翻译、中英文翻译、外文翻译
中国地质大学长城学院本科毕业设计外文资料翻译系别工程技术系专业机械设计制造及其自动化学生姓名彭江鹤学号 05211534指导教师王泽河职称教授2015 年 5 月 4 日液压传动系统作者：Hopmans, ArthurH.摘要液压传动是由液压泵、液压控制阀、液压执行元件和液压辅件组成的液压系统。
液压泵把机械能转换成液体的压力能，液压控制阀和液压辅件控制液压介质的压力、流量和流动方向，将液压泵输出的压力能传给执行元件，执行元件将液体压力能转换为机械能，以完成要求的动作。
关键词：液压传动；气压传动；传动系统；许多液压传动先前已经设计出允许操作者无限变化输出的变速器，或甚至逆转的传动装置的输出作为相对于输入。
通常情况下，这已经通过使用一个旋转斜盘是要么由操作者手动或操作液压动机来改变通过旋转泵头部具有轴向移动的活塞流动的液压流体的。
液压流体从泵头活塞的流动，依次转动的马达头通过激励相应的一组活塞在其中违背一固定凸轮的，因此，旋转安装在电动机头的输出轴。
通常情况下，在现有技术的变速器已被被设置有各种功能，例如齿轮减速，刹车设定装置等。
不幸的是，这些功能通常是提供外部发送的和显著增加整个装置的体积和质量。
申请人确定，这是很期望具有其中基本上所有的这些需要或希望的功能，可以在内部提供的发送，同时还产生一个非常有效的和非常有效的传输的综合传输。
特别是，这种类型的变速器上经常使用的设备，如“零转动半径”剪草机之类的其中一个潜在的危险情况面对操作者，旁观者和设备本身，如果设备我们允许继续被推进应的操作者释放控制，由于当操作者无意中从装置抛出或变得受伤。
因此，“故障自动刹车”机制经常被设置为传输自动地返回到中立配置在这种情况下，使得该装置不会继续供电，如果控制被释放。
先前传输这种类型的一般依靠某种外部设备，比如其目的是为了在操作者控制轴返回到中立位置应操作者释放所述轴的反操作偏压弹簧。
这种类型的外部设备，可以容易地由用户或篡改损坏。
柱塞泵毕业设计外文文献翻译
柱塞泵毕业设计外⽂⽂献翻译利⽤神经⽹络预测轴向柱塞泵的性能Mansour A Karkoub a, Osama E Gad a, Mahmoud G Rabie ba--就读于科威特的科威特⼤学⼯程与⽯油学院b--就读于埃及开罗的军事科技⼤学摘要本⽂推导了应⽤于轴向柱塞泵（斜轴式）的神经⽹络模型。
该模型采⽤的数据是由⼀个实验装置获得的。
这个正在进⾏的研究的⽬的是降低柱塞泵在⾼压下⼯作时的能量损耗。
然⽽，在最初我们要做⼀些研究来预测当前所设计的泵的响应。
神经⽹络模型具有前反馈的结构，并在测验过程中使⽤Levenberg-Marquardt优化技术。
该模型能够准确地预测柱塞泵的动态响应。
1、简介可变排量轴向柱塞泵是在流体动⼒系统中经常要⽤到的重要设备，如液压动⼒供应控制和静液压传动驱动器的控制。
本装置具有变量机制和功率-重量⽐特性，使其最适合于⾼功率电平的控制。
所设计的这种轴向柱塞泵拥有可靠性和简便的特点，然⽽其最重要的特征是可以变量输出。
⼈们在轴向柱塞泵领域已经做了很多研究，但是本⽂将只论述⼀下少数⼏⼈所做的贡献。
Kaliafetis和Costopoulos[5]⽤调压器研究了轴向柱塞变量泵的静态和动态特性。
所提出的模型的精确度依赖于制造商提供的动态运⾏曲线等数据。
他们得出结论，运⾏条件对泵的动态⾏为是⾮常关键的，⽽泵的动态⾏为可以通过减⼩压⼒设定值进⾏改善。
Harris等⼈[4]模拟和测量了轴向柱塞泵的缸体压⼒和进油流量脉动。
Kiyoshi和Masakasu[7]研究了斜盘式变量输送的轴向柱塞泵在运⾏时刻的实验上和理论上的静态和动态特性。
并提出了⼀种新的⽅法来预测泵在运⾏过程中的响应。
也对研究泵特性的新⽅法的有效性进⾏了实验验证，实验中使⽤了⼀个有宽、短⽽深的凹槽的配流盘。
Edge和Darling[2]研究了液压轴向柱塞泵的缸体压⼒和流量。
这个得出的模型经过了实验检验。
对于配流盘、缸体上设计的退⼑槽和泵的流量脉动对泵特性的影响都进⾏了验证。
液压系统外文文献翻译、中英文翻译、外文文献翻译
附录Hydraulic SystemHydraulic presser drive and air pressure drive hydraulic fluid as the transmission is made according to the 17th century, Pascal's principle of hydrostatic pressure to drive the development of an emerging technology, the United Kingdom in 1795 •Barman Joseph (Joseph Barman, 1749-1814), in London water as a medium to form hydraulic press used in industry, the birth of the world's first hydraulic press. Media work in 1905 will be replaced by oil-water and further improved.After the World War I (1914-1918) ,because of the extensive application of hydraulic transmission, especially after 1920, more rapid development. Hydraulic components in the late 19th century about the early 20th century, 20 years, only started to enter the formal phase of industrial production. 1925 Vickers (F. Vickers) the invention of the pressure balanced vane pump, hydraulic components for the modern industrial or hydraulic transmission of the gradual establishment of the foundation. The early 20th century G • Constantia scofluctuations of the energy carried out by passing theoretical and practical research; in 1910 on the hydraulic trans- mission (hydraulic coupling, hydraulic torque converter, etc.) contributions, so that these two areas of development.The Second World War (1941-1945) period, in the United States 30% of machine tool applications in the hydraulic transmission. It should be noted that the development of hydraulic transmission in Japan than Europe and the United States and other countries fornearly 20 years later. Before and after in 1955, the rapid development of Japan's hydraulic drive, set up in 1956, "Hydraulic Industry." Nearly 20 to 30 years, the development of Japan's fast hydraulic transmission, a world leader.Hydraulic transmission There are many outstanding advantages, it is widely used, such as general industrial use of plastics processing machinery, the pressure of machinery, machine tools, etc.; operating machinery engineering machinery, construction machinery, agricultural machinery, automobiles, etc.; iron and steel industry metallurgical machinery, lifting equipment, such as roller adjustment device; civil water projects with flood control and dam gate devices, bed lifts installations, bridges and other manipulation of institutions; speed turbine power plant installations, nuclear power plants, etc.; ship from the deck heavy machinery (winch), the bow doors, bulkhead valve, stern thruster, etc.; special antenna technology giant with control devices, measurement buoys, movements such as rotating stage; military-industrial control devices used in artillery, ship anti- rolling devices, aircraft simulation, aircraft retractable landing gear and rudder control devices and other devices.A complete hydraulic system consists of five parts, namely, power components, the implementation of components, control components, auxiliary components and hydraulic oil.The role of dynamic components of the original motive fluid into mechanical energy to the pressure that the hydraulic system of pumps, it is to power the entire hydraulic system. The structure of the form of hydra- ulic pump gears are generally pump, vane pump and piston pump.Implementation of components (such as hydraulic cylinders and hydraulic motors) which isthe pressure of the liquid can be converted to mechanical energy to drive the load for a straight line reciprocating movement or rotational movement.Control components (that is, the various hydraulic valves) in the hydraulic system to control and regulate the pressure of liquid, flow rate and direction. According to the different control functions, hydraulic pressure control valve can be divided into valves, flow control valves and directional control valve. Pressure control valves are divided into benefits flow valve (safety valve), pressure relief valve, sequence valve, pressure relays, etc.; flow control valves including throttle, adjusting the valves, flow diversion valve sets, etc.; directional control valve includes a one-way valve , one-way fluid control valve, shuttle valve, valve and so on. Under the control of different ways, can be divided into the hydraulic valve control switch valve, control valve and set the value of the ratio control valve.Auxiliary components, including fuel tanks, oil filters, tubing and pipe joints, seals, pressure gauge, oil level, such as oil dollars.Hydraulic oil in the hydraulic system is the work of the energy transfer medium, there are a variety of mineral oil, emulsion oil hydraulic molding Hop categories.The role of the hydraulic system is to help humanity work. Mainly by the implementation of components to rotate or pressure into a reciprocating motion.Hydraulic system and hydraulic power control signal is composed of two parts, the signal control of some parts of the hydraulic power used to drive the control valve movement.Part of the hydraulic power means that the circuit diagram used to show the differentfunctions of the interrelationship between components. Containing the source of hydraulic pump, hydraulic motor and auxiliary components; hydraulic control part contains a variety of control valves, used to control the flow of oil, pressure and direction; operative or hydraulic cylinder with hydraulic motors, according to the actual requirements of their choice.In the analysis and design of the actual task, the general block diagram shows the actual operation of equipment. Hollow arrow indicates the signal flow, while the solid arrows that energy flow.Basic hydraulic circuit of the action sequence - Control components (two four-way valve) and the spring to reset for the implementation of components (double-acting hydraulic cylinder), as well as the extending and retracting the relief valve opened and closed. For the implementation of components and control components, presentations are based on the corresponding circuit diagram symbols, it also introduced ready made circuit diagram symbols.Working principle of the system, you can turn on all circuits to code. If the first implementation of components numbered 0, the control components associated with the identifier is 1. Out with the implementation of components corresponding to the identifier for the even components, then retracting and implementation of components corresponding to the identifier for the odd components. Hydraulic circuit carried out not only to deal with numbers, but also to deal with the actual device ID, in order to detect system failures.DIN ISO1219-2 standard definition of the number of component composition, which includes the following four parts: device ID, circuit ID, component ID and component ID.The entire system if only one device, device number may be omitted.Practice, another way is to code all of the hydraulic system components for numbers at this time, components and component code should be consistent with the list of numbers. This method is particularly applicable to complex hydraulic control system, each control loop are the corresponding number with the systemWith mechanical transmission, electrical transmission compared to the hydraulic drive has the following advantages:1. a variety of hydraulic components can easily and flexibly to layout.2. light weight, small size, small inertia, fast response.3. to facilitate manipulation of control, enabling a wide range of stepless speed regulation (speed range of 2000:1).4. to achieve overload protection automatically.5. the general use of mineral oil as a working medium, the relative motion can be self-lubricating surface, long service life;6. it is easy to achieve linear motion .7. it is easy to achieve the automation of machines, when the joint control of the use of electro-hydraulic, not only can achieve a higher degree of process automation, and remote control can be achieved.The shortcomings of the hydraulic system:1. as a result of the resistance to fluid flow and leakage of the larger, so less efficient. If not handled properly, leakage is not only contaminated sites, but also may cause fire and explosion.2. vulnerable performance as a result of the impact of temperature change, it would be inappropriate in the high or low temperature conditions.3. the manufacture of precision hydraulic components require a higher, more expensive and hence the price.4. due to the leakage of liquid medium and the compressibility and can not be strictly the transmission ratio.5. hydraulic transmission is not easy to find out the reasons for failure; the use and maintenance requirements for a higher level of technology.In the hydraulic system and its system, the sealing device to prevent leakage of the work of media within and outside the dust and the intrusion of foreign bodies. Seals played the role of components, namely seals. Medium will result in leakage of waste, pollution and environmental machinery and even give rise to malfunctioning machinery and equipment for personal accident. Leakage within the hydraulic system will cause a sharp drop in volumetric efficiency, amounting to less than the required pressure, can not even work. Micro-invasive system of dust particles, can cause or exacerbate friction hydraulic component wear, and further lead to leakage.Therefore, seals and sealing device is an important hydraulic equipment components. The reliability of its work and life, is a measure of the hydraulic system an important indicator of good or bad. In addition to the closed space, are the use of seals, so that two adjacent coupling surface of the gap between the need to control the liquid can be sealed following the smallest gap. In the contact seal, pressed into self-seal-style and self-styled self-tight seal (ie, sealed lips) two.The three hydraulic system diseases1. as a result of heat transmission medium (hydraulic oil) in the flow velocity in various parts of the existence of different, resulting in the existence of a liquid within the internal friction of liquids and pipelines at the same time there is friction between the inner wall, which are a result of hydraulic the reasons for the oil temperature. Temperature will lead to increased internal and external leakage, reducing its mechanical efficiency. At the same time as a result of high temperature, hydraulic oil expansion will occur, resulting in increased com- pression, so that action can not be very good control of transmission. Solution: heat is the inherent characteristics of the hydraulic system, not only to minimize eradication. Use a good quality hydraulic oil, hydraulic piping arrangement should be avoided as far as possible the emergence of bend, the use of high-quality pipe and fittings, hydraulic valves, etc.2. the vibration of the vibration of the hydraulic system is also one of its malaise. As a result of hydraulic oil in the pipeline flow of high-speed impact and the control valve to open the closure of the impact of the process are the reasons for the vibration system. Strong vibration control action will cause the system to error, the system will also be some of the more sophisticated equipment error, resulting in system failures. Solutions: hydraulic pipe should be fixed to avoid sharp bends. To avoid frequent changes in flow direction, can not avoid damping measures should be doing a good job. The entire hydraulic system should have a good damping measures, while avoiding the external local oscillator on the system.3. the leakage of the hydraulic system leak into inside and outside the leakage. Leakagerefers to the process with the leak occurred in the system, such as hydraulic piston-cylinder on both sides of the leakage, the control valve spool and valve body, such as between the leakage. Although no internal leakage of hydra- ulic fluid loss, but due to leakage, the control of the established movements may be affected until the cause system failures. Outside means the occurrence of leakage in the system and the leakage between the external environment. Direct leakage of hydraulic oil into the environment, in addition to the system will affect the working environment, not enough pressure will cause the system to trigger a fault. Leakage into the environment of the hydraulic oil was also the danger of fire. Solution: the use of better quality seals to improve the machining accuracy of equipment.Another: the hydraulic system for the three diseases, it was summed up: "fever, with a father拉稀" (This is the summary of the northeast people). Hydraulic system for the lifts, excavators, pumping station, dynamic, crane, and so on large-scale industry, construction, factories, enterprises, as well as elevators, lifting platforms, Deng Axle industry and so on.Hydraulic components will be high-performance, high-quality, high reliability, the system sets the direction of development; to the low power, low noise, vibration, without leakage, as well as pollution control, water-based media applications to adapt to environmental requirements, such as the direction of development; the development of highly integrated high power density, intelligence, macaronis and micro-light mini-hydraulic components; active use of new techniques, new materials and electronics, sensing and other high-tech.---- Hydraulic coupling to high-speed high-power and integrated development of hydraulic transmission equipment, development of water hydraulic coupling medium speedand the field of automotive applications to develop hydraulic reducer, improve product reliability and working hours MTBF; hydraulic torque converter to the development of high-power products, parts and components to improve the manufacturing process technology to improve reliability, promote computer-aided technology, the development of hydraulic torque converter and power shift transmission technology supporting the use of ; Clutch fluid viscosity should increase the quality of products, the formation of bulk to the high-power and high-speed direction.Pneumatic Industry:---- Products to small size, light weight, low power consumption, integrated portfolio of development, the implementation of the various types of components, compact structure, high positioning accuracy of the direction of development; pneumatic components and electronic technology, to the intelligent direction of development; component performance to high-speed, high-frequency, high-response, high-life, high temp- erature, high voltage direction, commonly used oil-free lubrication, application of new technology, new technology and new materials.1. Used high-pressure hydraulic components and the pressure of continuous work to reach 40Mpa, the maximum pressure to achieve instant 48Mpa;2. Diversification of regulation and control;3. To further improve the regulation performance, increase the efficiency of the power train;4. Development and mechanical, hydraulic, power transmission of the composite portfolio adjustment gear;5. Development of energy saving, energy efficient system function;6. To further reduce the noise;7. Application of Hydraulic Cartridge Valves thread technology, compact structure, to reduce the oil spill.液压系统液压传动和气压传动称为流体传动，是根据17世纪帕斯卡提出的液体静压力传动原理而发展起来的一门新兴技术，1795年英国约瑟夫•布拉曼(Joseph Braman,1749-1814)，在伦敦用水作为工作介质，以水压机的形式将其应用于工业上，诞生了世界上第一台水压机。
毕业设计论文-四柱式液压机液压系统设计(含全套CAD图纸)
属成型、薄板拉伸以及冲压、弯曲、翻边、校正等工艺的四柱式万能液压机。 性能特点：本液压机具有调整、手动及半自动三种工作方式，可实现定压和定程两种工艺 方式。定压成型时，在压制后有保压延时及自动回程动作。工作台中间装有顶出装置，除 顶出制品外，还可作为液压垫用于薄板拉伸制件的压边成型工艺，其工作压力与行程可根 据工艺需要在规定范围内调整；可用继电器控制或 PLC 控制的电气控制系统。 主要技术参数：公称力（最大压力）2000KN，回程力 400 KN，顶出力 350KN，液体最大工 作压力 25 Mpa，拉伸滑块行程 700mm, 顶出活塞最大行程 250mm, 滑块距工作台最大距离 内 1100mm。
液压系统外文文献翻译中英文
外文文献翻译(含：英文原文及中文译文)英文原文Hydraulic systemW Arnold1 IntroductionThe hydraulic station is called a hydraulic pump station and is an independent hydraulic device. It is step by step to supply oil. And control the direction of hydraulic oil flow, pressure and flow, suitable for the host and hydraulic equipment can be separated on the various hydraulic machinery.After the purchase, the user only needs to connect the hydraulic station and the actuator (hydraulic or oil motor) on the mainframe with different tubings. The hydraulic machine can realize various specified actions and working cycles.The hydraulic station is a combination of manifolds, pump units or valve assemblies, electrical boxes, and tank electrical boxes. Each part function is:The pump unit is equipped with a motor and an oil pump, which is the power source of the hydraulic station and can convert mechanical energy into hydraulic oil pressure energy.V alve combination - its plate valve is mounted on the vertical plate, and the rear plate is connected with the same function as the manifold.Oil manifolds - assembled from hydraulic valves and channel bodies. It regulates hydraulic oil pressure, direction and flow.Box--a semi-closed container for plate welding. It is also equipped with an oil screen, an air filter, etc., which is used for cooling and filtering of oil and oil.Electrical box - divided into two types: one is to set the external lead terminal board; one is equipped with a full set of control appliances.The working principle of the hydraulic station: The motor drives the oil pump to rotate, then the pump sucks oil from the oil tank and supplies oil, converts the mechanical energy into hydraulic pressure energy, and the hydraulic oil passes through the manifold (or valve assembly) to adjust the direction, pressure and flow and then passes through the external tube. The way to the hydraulic cylinder or oil motor in the hydraulic machinery, so as to control the direction of the hydraulic motor, the strength of the speed and speed, to promote all kinds of hydraulic machinery to do work.(1) Development history of hydraulic pressureThe development history of hydraulics (including hydraulic power, the same below), pneumatics, and seals industry in China can be roughly divided into three stages, namely: the starting stage in the early 1950s to the early 60s; and the professional in the 60s and 70s. The growth stage of the production system; the 80-90's is a stage of rapid development. Among them, the hydraulic industry began in the early 1950s with thedevelopment of hydraulic machines such as Grinding Machines, broaching machines, and profiling lathes, which were produced by the machine tool industry. The hydraulic components were produced by the hydraulic workshop in the machine tool factory, and were produced for self use. After entering the 1960s, the application of hydraulic technology was gradually promoted from the machine tool to the agricultural machinery and engineering machinery. The original hydraulic workshop attached to the main engine plant was independent and became a professional manufacturer of hydraulic components. In the late 1960s and early 1970s, with the continuous development of mechanization of production, particularly in the provision of highly efficient and automated equipment for the second automobile manufacturing plant, the hydraulic component manufacturing industry witnessed rapid development. The batch of small and medium-sized enterprises also began to become specialized manufacturers of hydraulic parts. In 1968, the annual output of hydraulic components in China was close to 200,000 pieces. In 1973, in the fields of machine tools, agricultural machinery, construction machinery and other industries, the professional factory for the production of hydraulic parts has grown to over 100, and its annual output exceeds 1 million pieces. Such an independent hydraulic component manufacturing industry has taken shape. At this time, the hydraulic product has evolved from the original imitation Su product intoa combination of imported technology and self-designed products. The pressure has been developed towards medium and high pressures, and electro-hydraulic servo valves and systems have been developed. The application of hydraulics has been further expanded. The pneumatic industry started a few years later than hydraulics, and it was only in 1967 that it began to establish a professional pneumatic components factory. Pneumatic components began to be manufactured and sold as commodities. Its sealing industry including rubber seals, flexible graphite seals, and mechanical seals started from the production of common O-rings, oil seals, and other extruded rubber seals and asbestos seal products in the early 1950s. In the early 1960s, it began to develop and produce flexible products. Graphite seals and mechanical seals and other products. In the 1970s, a batch of batches of professional production plants began to be established one after another in the systems of the former Ministry of Combustion, the Ministry of Agriculture, and the Ministry of Agricultural Machinery, formally forming the industry, which laid the foundation for the development of the seal industry.In the 1980s, under the guidance of the national policy of reform and opening up, with the continuous development of the machinery industry, the contradiction between the basic components lags behind the host computer has become increasingly prominent and caused the attention of all relevant departments. To this end, the former Ministry of Machinesestablished the General Infrastructure Industry Bureau in 1982, and unified the original pneumatic, hydraulic, and seal specialties that were scattered in the industries of machine tools, agricultural machinery, and construction machinery, etc. The management of a piece of office, so that the industry in the planning, investment, the introduction of technology and scientific research and development and other aspects of the basic parts of the bureau's guidance and support. This has entered a period of rapid development, it has introduced more than 60 foreign advanced technology, of which more than 40 hydraulic, pneumatic 7, after digestion and absorption and technological transformation, are now mass production, and has become the industry's leading products . In recent years, the industry has intensified its technological transformation. From 1991 to 1998, the total investment of national, local, and corporate self-raised funds totaled about 2 billion yuan, of which more than 1.6 billion were hydraulic. After continuous technological transformation and technological breakthroughs, the technical level of a group of major enterprises has been further improved, and technological equipment has also been greatly improved, laying a good foundation for forming a high starting point, specialization, and mass production. In recent years, under the guidance of the principle of common development of multiple ownership systems in the country, various small and medium-sized enterprises with different ownership have rapidly emerged and haveshown great vitality. With the further opening up of the country, foreign-funded enterprises have developed rapidly, which plays an important role in raising industry standards and expanding exports. So far China has established joint ventures with famous manufacturers in the United States, Germany, Japan and other countries or directly established piston pumps/motors, planetary speed reducers, hydraulic control valves, steering gears, hydraulic systems, hydrostatic transmissions, and hydraulic components. The company has more than 50 manufacturing enterprises such as castings, pneumatic control valves, cylinders, gas processing triplets, rubber seals, and mechanical seals, and has attracted more than 200 million U.S. dollars in foreign capital.(2) Current statusBasic profileAfter more than 40 years of hard work, China's hydraulics, pneumatics and seals industry has formed a complete industrial system with a certain level of production capacity and technical level. According to the statistics of the third n ational industrial census in 1995, China’s state-owned, privately-owned, cooperative, village-run, individual, and “funded enterprises” have annual sales income of more than 1 million yuan in hydraulic, pneumatic, and seal industrial townships and above. There are a total of more than 1,300 companies, including about 700 hydraulics, and about 300 pneumatic and sealing parts. According to thestatistics of the international industry in 1996, the total output value of the hydraulic industry in China was about 2.448 billion yuan, accounting for the 6th in the world; the total output value of the pneumatic industry was about 419 million yuan, accounting for the world’s10 people.2. Current supply and demand profileWith the introduction of technology, independent development and technological transformation, the technical level of the first batch of high-pressure plunger pumps, vane pumps, gear pumps, general hydraulic valves, oil cylinders, oil-free pneumatic components and various types of seals has become remarkable. Improve, and can be stable mass production, provide guarantees for all types of host to improve product quality. In addition, certain achievements have also been made in the aspects of CAD, pollution control, and proportional servo technology for hydraulic pneumatic components and systems, and have been used for production. So far, the hydraulic, pneumatic and seal products have a total of about 3,000 varieties and more than 23,000 specifications. Among them, there are about 1,200 types of hydraulic pressure, more than 10,000 specifications (including 60 types of hydrodynamic products, 500 specifications); about 1350 types of pneumatic, more than 8,000 specifications; there are also 350 types of rubber seals, more than 5000 The specifications are now basically able to adapt to the general needs ofvarious types of mainframe products. The matching rate for major equipment sets can reach more than 60%, and a small amount of exports has started.In 1998, the domestic production of hydraulic components was 4.8 million pieces, with sales of about 2.8 billion yuan (of which mechanical systems accounted for 70%); output of pneumatic components was 3.6 million pieces, and sales were about 550 million yuan (including mechanical systems accounting for about 60%) The production of seals is about 800 million pieces, and the sales volume is about 1 billion yuan (including about 50% of mechanical systems). According to the statistics of the annual report of the China Hydraulic and Pneumatic Sealing Industry Association in 1998, the production and sales rate of hydraulic products was 97.5% (101% of hydraulic power), 95.9% of air pressure, and 98.7% of seal. This fully reflects the basic convergence of production and sales.Although China's hydraulic, pneumatic and sealing industries have made great progress, there are still many gaps compared with the development needs of the mainframe and the world's advanced level, which are mainly reflected in the variety, performance and reliability of products. . Take hydraulic products as an example, the product varieties are only 1/3 of the foreign country, and the life expectancy is 1/2 of that of foreign countries. In order to meet the needs of key hosts, imported hosts, and majortechnical equipment, China has a large number of imported hydraulic, pneumatic, and sealing products every year. According to customs statistics and relevant data analysis, in 1998, the import volume of hydraulic, pneumatic and seal products was about 200 million U.S. dollars, of which the hydraulic pressure was about 140 million U.S. dollars, the pneumatics were 30 million U.S. dollars, and the seal was about 0.3 billion U.S. dollars. The year is slightly lower. In terms of amount, the current domestic market share of imported products is about 30%. In 1998, the total demand for hydraulic parts in the domestic market was about 6 million pieces, and the total sales volume was 4 billion yuan; the total demand for pneumatic parts was about 5 million pieces, and the total sales volume was over 700 million yuan; the total demand for seals was about 1.1 billion yuan. Pieces, total sales of about 1.3 billion yuan. (3) Future developments1. The main factors affecting development(1) The company's product development capability is not strong, and the level and speed of technology development can not fully meet the current needs for advanced mainframe products, major technical equipment and imported equipment and maintenance;(2) Many companies have lagged behind in manufacturing process, equipment level and management level, and their sense of quality is not strong, resulting in low level of product performance, unstable quality,poor reliability, and insufficiency of service, and lack of user satisfaction. And trusted branded products;(3) The degree of professional specialization in the industry is low, the power is scattered, the duplication of the low level is serious, the product convergence between the region and the enterprise leads to blind competition, and the prices are reduced each other, thus the efficiency of the enterprise is reduced, the funds are lacking, and the turnover is difficult. Insufficient investment in development and technological transformation has severely restricted the overall level of the industry and its competitive strength.(4) When the degree of internationalization of the domestic market is increasing, foreign companies have gradually entered the Chinese market to participate in competition, coupled with the rise of domestic private, cooperative, foreign-funded, and individual enterprises, resulting in increasing impact on state-owned enterprises. .2. Development trendWith the continuous deepening of the socialist market economy, the relationship between supply and demand in the hydraulic, pneumatic and sealed products has undergone major changes. The seller market characterized by “shortage” has basically become a buyer’s market characterized by “structured surplus”. Replaced by. From the perspective of overall capacity, it is already in a trend of oversupply, and in particular,general low-grade hydraulic, pneumatic and seals are generally oversupply; and like high-tech products with high technological content and high value and high value-added products that are urgently needed by the host, Can not meet the needs of the market, can only rely on imports. After China's entry into the WTO, its impact may be greater. Therefore, during the “10th Five-Y ear Plan” period, the growth of the industry’s output value must not only rely on the growth of quantity. Instead, it should focus on the structural contradiction of the industry and intensify efforts to adjust the industrial structure and product structure. It should be based on the improvement of quality. Product technology upgrades in order to adapt to and stimulate market demand, and seek greater development.2. Hydraulic application on power slide(1) Introduction of Power Sliding TableUsing the binding force curve diagram and the state space analysis method to analyze and study the sliding effect and the smoothness of the sliding table of the combined machine tool, the dynamics of the hydraulic drive system of the sliding table—the self-regulating back pressure regulating system are established. mathematical model. Through the digital simulation system of the computer, the causes and main influencing factors of the slide impact and the motion instability are analyzed. What kind of conclusions can be drawn from those, if we canreasonably design the structural dimensions of hydraulic cylinders and self-regulating back pressure regulators ——The symbols used in the text are as follows:s 1 - flow source, that is, the flow rate of the governor valve outlet;S el —— sliding friction of the sliding table;R - the equivalent viscous friction coefficient of the slide;I 1 - quality of slides and cylinders;12 - self-adjusting back pressure valve core quality;C 1, c 2 - liquid volume without cylinder chamber and rod chamber;C 2 - Self-adjusting back pressure valve spring compliance;R 1, R2 - Self-adjusting back pressure valve damping orifice fluid resistance;R 9 - Self-adjusting back pressure valve valve fluid resistance;S e2——initial pre-tightening force of self-adjusting back pressure valve spring;I 4, I5 - Equivalent liquid sense of the pipeline;C 5, C 6 - equivalent liquid capacity of the pipeline;R 5, R7 - Equivalent liquid resistance of the pipeline;V 3, V4 - cylinder rodless cavity and rod cavity volume;P 3, P4—pressure of the rodless cavity and rod cavity of the cylinder;F - the slide bears the load;V - speed of slide motion;In this paper, the power bond diagram and the state space splitting method are used to establish the system's motion mathematical model, and the dynamic characteristics of the slide table can be significantly improved.In the normal operation of the combined machine tool, the magnitude of the speed of the slide, its direction and the load changes it undergoes will affect its performance in varying degrees. Especially in the process of work-in-process, the unsteady movement caused by the advancing of the load on the slide table and the cyclical change of the load will affect the surface quality of the workpiece to be machined. In severe cases, the tool will break. According to the requirements of the Dalian Machine Tool Plant, the author used the binding force curve diagram and the state space analysis method to establish a dynamic mathematical model of a self-adjusting back pressure and speed adjustment system for the new hydraulic drive system of the combined machine tool slide. In order to improve the dynamic characteristics of the sliding table, it is necessary to analyze the causes and main influencing factors of the impetus and movement of the sliding table. However, it must pass the computer's digital simulation and the final results obtained from the research.(2) Dynamic Mathematical ModelThe working principle diagram of the self-adjusting back pressure speedregulation system of the combined machine tool slide hydraulic drive system is shown in the figure. This system is used to complete the work-cycle-stop-rewind. When the sliding table is working, the three-position four-way reversing valve is in the illustrated position. The oil supply pressure of the oil pump will remain approximately constant under the effective action of the overflow valve, and the oil flow passes through the reversing valve and adjusts the speed. The valve enters the rodless chamber of the cylinder to push the slide forward. At the same time, the pressurized oil discharged from the rod chamber of the cylinder will flow back to the tank through the self-regulating back pressure valve and the reversing valve. During this process, there was no change in the operating status of both the one-way valve and the relief valve. The complex and nonlinear system of the hydraulic drive system of the self-adjusting back pressure governor system is a kind of self-adjusting back-pressure governor system. To facilitate the study of its dynamic characteristics, a simple and reasonable dynamic mathematical model that only considers the main influencing factors is established. Especially important [1][2]. From the theoretical analysis and the experimental study, we can see that the system process time is much longer than the process time of the speed control valve. When the effective pressure bearing area of the rodless cavity of the fuel tank is large, the flow rate at the outlet of the speed control valve is instantaneous. The overshoot is reflected in thesmall change in speed of the slide motion [2]. In order to further broaden and deeply study the dynamic characteristics of the system so that the research work can be effectively performed on a miniature computer, this article will further simplify the original model [2], assuming that the speed control valve is output during the entire system pass. When the flow is constant, this is considered to be the source of the flow. The schematic diagram of the dynamic model structure of this system is shown in Fig. 2. It consists of a cylinder, a sliding table, a self-adjusting back pressure valve, and a connecting pipe.The power bond graph is a power flow graph. It is based on the transmission mode of the system energy, based on the actual structure, and uses the centralized parameters to represent the role of the subsystems abstractly as a resistive element R, a perceptual element I, and a capacitive element. Three kinds of role of C. Using this method, the physical concept of modeling is clear, and combined with the state-space analysis method, the linear system can be described and analyzed more accurately. This method is an effective method to study the dynamic characteristics of complex nonlinear systems in the time domain. According to the main characteristics of each component of the self-adjusting back pressure control system and the modeling rules [1], the power bond diagram of the system is obtained. The upper half of each key in the figure represents the power flow. The two variables that makeup the power are the force variables (oil pressure P and force F) and the flow variables (flow q and velocity v). The O node indicates that the system is connected in parallel, and the force variables on each key are equal and the sum of the flow variables is zero; 1 The nodes represent the series connection in the system, the flow variables on each key are equal and the sum of the force variables is Zero. TF denotes a transformer between different energy forms. The TF subscripted letter represents the conversion ratio of the flow variable or the force variable. The short bar on the key indicates the causal relationship between the two variables on the key. The full arrow indicates the control relationship. There are integral or differential relationships between the force and flow variables of the capacitive and perceptual elements in the three types of action elements. Therefore, a complex nonlinear equation of state with nine state variables can be derived from Fig. 3 . In this paper, the research on the dynamic characteristics of the sliding table starts from the two aspects of the slide's hedging and the smoothness of the motion. The fourth-order fixed-length Runge-Kutta is used for digital simulation on the IBM-PC microcomputer.(3) Slide advanceThe swaying phenomenon of the slide table is caused by the sudden disappearance of the load acting on the slide table (such as drilling work conditions). In this process, the table load F, the moving speed V, and thepressure in the two chambers of the cylinder P3 and P4 can be seen from the simulation results in Fig. 4. When the sliding table moves at a uniform speed under the load, the oil pressure in the rodless cavity of the oil cylinder is high, and a large amount of energy is accumulated in the oil. When the load suddenly disappears, the oil pressure of the cavity is rapidly reduced, and the oil is rapidly reduced. When the high-pressure state is transferred to the low-pressure state, a lot of energy is released to the system, resulting in a high-speed forward impact of the slide. However, the front slide of the sliding table causes the pressure in the rod cavity of the oil cylinder to cause the back pressure to rise, thereby consuming part of the energy in the system, which has a certain effect on the kicking of the slide table. We should see that in the studied system, the inlet pressure of the self-adjusting back pressure valve is subject to the comprehensive effect of the two-chamber oil pressure of the oil cylinder. When the load suddenly disappears, the pressure of the self-adjusting back pressure valve rapidly rises and stably exceeds the initial back pressure value. It can be seen from the figure that self-adjusting back pressure in the speed control system when the load disappears, the back pressure of the cylinder rises more than the traditional speed control system, so the oil in the rod cavity of the cylinder absorbs more energy, resulting in the amount of forward momentum of the slide It will be about 20% smaller than traditionalspeed control systems. It can be seen from this that the use of self-adjusting back-gear speed control system as a drive system slider has good characteristics in suppressing the forward punch, in which the self-adjusting back pressure valve plays a very large role.(4) The smoothness of the slideWhen the load acting on the slide changes periodically (such as in the case of milling), the speed of the slide will have to fluctuate. In order to ensure the processing quality requirements, it must reduce its speed fluctuation range as much as possible. From the perspective of the convenience of the discussion of the problem, assume that the load changes according to a sine wave law, and the resulting digital simulation results are shown in Figure 5. From this we can see that this system has the same variation rules and very close numerical values as the conventional speed control system. The reason is that when the change of the load is not large, the pressure in the two chambers of the fuel tank will not have a large change, which will eventually lead to the self-regulating back pressure valve not showing its effect clearly.(5) Improvement measuresThe results of the research show that the dynamic performance of a sliding table with self-regulating back pressure control system as a drive system is better than that of a traditional speed control system. To reduce the amount of kick in the slide, it is necessary to rapidly increase the backpressure of the rod cavity when the load disappears. To increase the smoothness of the sliding table, it is necessary to increase the rigidity of the system. The main measure is to reduce the volume of oil. From the system structure, it is known that the cylinder has a large volume between the rod cavity and the oil discharge pipe, as shown in Fig. 6a. Its existence in terms of delay and attenuation of the self-regulating back pressure valve function, on the other hand, also reduces the rigidity of the system, it will limit the further improvement of the propulsion characteristics and the smoothness of the motion. Thus, improving the dynamic characteristics of the sliding table can be handled by two methods: changing the cylinder volume or changing the size of the self-regulating back pressure valve. Through the simulation calculation of the structural parameters of the system and the comparison of the results, it can be concluded that the ratio of the volume V4 between the rod cavity and the oil discharge pipe to the volume V3 between the rodless cavity and the oil inlet pipe is changed from 5.5 to 5.5. At 1 oclock, as shown in the figure, the diameter of the bottom end of the self-adjusting back pressure valve is increased from the original 10mm to 13mm, and the length of the damper triangle groove is reduced from the original lmm to 0.7mm, which will enable the front of the slide table. The impulse is reduced by 30%, the transition time is obviously shortened, and the smoothness of the slide motion will also be greatly improved.中文译文液压系统W Arnold1. 绪论液压站称液压泵站,是独立的液压装置。
液压与气压传动课程设计指导书参考文献
液压与气压传动课程设计指导书参考文献一、引言液压与气压传动是现代工程中常用的能量传递方式之一。
它们通过利用液体和气体的性质，将能量从一个地方传递到另一个地方。
本文将针对液压与气压传动的课程设计进行指导，提供相关参考文献，以帮助学生深入了解和掌握这一领域的知识。
二、液压与气压传动的基本原理1. 液压传动液压传动是利用液体在封闭管路中传递力和能量的方式。
其基本原理是利用流体的不可压缩性和流体静力学原理，通过增大或减小流体静力作用面积来实现力的放大或减小。
常见的液压元件包括油泵、阀门、油缸等。
参考文献：•Rouse, E. (2012). Fluid power circuits and controls: fundamentals and applications. John Wiley & Sons.•Napolitano, M. (2005). Introduction to fluid power. Pearson Education.2. 气压传动气压传动是利用气体在封闭管路中传递力和能量的方式。
其基本原理是利用气体的可压缩性和气体静力学原理，通过改变气体的压力来实现力的放大或减小。
常见的气压元件包括压缩机、气缸、阀门等。
参考文献：•Johnson, C. D. (2006). Process control instrumentation technology.Pearson Education.•Esposito, A., Esposito, M., & Esposito, M. (2014). Fluid power with applications. Pearson Education.三、液压与气压传动的应用领域液压与气压传动广泛应用于各个工程领域，例如机械制造、航空航天、汽车工业等。
以下是一些常见的应用领域：1. 工程机械液压与气压传动在工程机械中起到了至关重要的作用。
《液压传动》双语教学实践与探索
2008年第6期(总第112期)牡丹江教育学院学报J oU R N A L oF M U D A N J I A N G C oL L E G E()F E D U C A T I oNN o．6．2008Ser ial N o．112《液压传动》双语教学实践与探索牛国玲臧克江桂兴春李彩花●(佳木斯大学机械工程学院，黑龙江佳木斯154007)[摘要]通过对影响《液压传动>双语教学各项因素的研究分析，阐述了开展《液压传动)双语教学工作应解决的重要问题和解决问题的措施，并对“英语运用度”这一指标对教学效果的影响进行了对比研究，提出了。
英语运用度”的最佳取值范围．[关键词]液压传动}双语教学；英语运用度[中图分类号]T H l37‘[文献标识码]A[文章编号]1009—2323(2008)06一0122—032001年8月，国家教育部在《关于加强高等学校本科教学提高教学质量的若干意见》中提出了加强大学本科教学的12项措施，其中要求各高校在三年内开设5％一10％的双语课程。
为落实这一精神，根据教学实际，自2003年起，我们以《液压传动》课程为载体，开始了双语教学的研究与探索工作。
通过研究与探索，发现影响双语教学效果的因素很多，需要认真对待各种影响因素，以期更好地推动和促进双语教学，提高教学质量，达到双语教学的目的。
1．<液压传动》课程采用双语教学所具备的基本条件《液压传动》是机械设计制造及其自动化专业的一门专业基础课，它以介绍液压传动基础知识、液压元件、典型液压传动系统及其设计为主要内容。
我们一直承担该课程的主讲任务．具有丰富的教学经验和实践经验，尤其是最近几年，教研室的教师相继攻读博士和硕士学位，英语水平也大大提高。
同时，授课对象是大三年级下半学期的学生，在学生学习该课程之前不仅完成了大学英语四学期的课程，而且已经选修了《机械工程专业英语》课程，因此，开展《液压传动》双语教学时，学生已经具备了扎实的英语基础。
28.液压与气压传动
中国海洋大学本科生课程大纲课程属性：公共基础/通识教育/学科基础/专业知识/工作技能，课程性质：必修、选修一、课程介绍1.课程描述：《液压与气压传动》是机械设计制造及其自动化、轮机工程等专业的一门的重要的专业基础课程。
它以流体作为能量传递的媒介，具有优良的静动态性能，是一种重要的传动与控制手段，在海洋、陆地、航空等领域的机电装备上具有广泛应用。
对培养学生的思维素质、创新能力、科学精神以及解决实际问题的能力都具有十分重要的作用。
本课程包括传动技术组成及特点、液压流体力学基础（工作介质特性、缝隙流动、孔口流动等）、动力元件、执行元件、控制元件、辅助元件、基本回路、典型系统分析与设计等。
通过该课程的学习与大量训练，要求同学们掌握流体传动的元件及系统的分析与设计的基本方法和程序，并能够利用相关理论与方法，对流体传动元件及系统进行研究、改造、研发。
2.设计思路：结合学生的认识过程及接受能力，由浅入深、由易到难、循序渐进，从元件结构原理及应用到基本回路分析与应用，到具体实际生产中的复杂系统分析、应用与研发，本课程主要以多媒体教学方式进行，同时辅以实物拆装、元件及回路实验等大量的训练，让同学们掌握流体传动元件及系统基本分析、设计方法。
本课程包括四个模块：流体传动基础、油液液压传动技术、纯水液压技术、气压传动技术。
具体要求学生掌握以下专业知识和技能：（1）流体传动基础以讲授为主，辅助以电子教案和多媒体课件，重点强调规范的学习、训练和掌握。
- 5 -明确《液压与气压传动》的范畴及基础，包括○1传动技术分类、组成、特点及本质关系；○2流体力学基础：工作介质特性、液压流体力学（基本方程、缝隙流动、孔口流动）、气体动力学等；○3流体传动研究前沿及发展方向。
（2）油液传压技术：以讲授为主，辅助以电子教案和多媒体课件，按液压系统组成，由浅入深、由易到难、循序渐进的讲授○1动力元件、执行元件、控制元件、辅助元件等的结构、工作原理及特性；○2基本回路分析与设计；○3典型液压系统分析。
中英文阀门名称对照表
中英文阀门名称对照表1-01自动阀门Self-acting valve依靠介质本身的能力而自行动作的阀门1-02驱动阀门Actuanted valve借助手动、电力、液压或气压来操纵的阀门2-01闸阀Gate valve,slide valve启闭件(闸板)由阀杆带动，沿阀座密封面做升降运动的阀门2-02平行式闸阀Parallel gate valve,parallel slide valve闸板的两侧密封面相互平行的闸阀2-03楔式闸阀Wedge gate valve闸板的两侧密封面成楔状的闸阀2-04升降杆式闸阀Outside screw stem rising through handwheel type gate valve 阀杆做升降运动，其传动螺纹在体腔外部的闸阀2-05旋转杆式闸阀Inside screw nonrising stem type gate valve阀杆作旋转运动,其传动螺纹在体腔内部的闸阀2-06快速启闭闸阀Quick open-and-close gate valve阀杆既作旋转又作升降运动的闸阀2-07缩口闸阀Contraction cavity gate valve阀体内的通道直径不同,阀座密封面处的直径小于法兰连接处的直径的闸阀2-08平板闸阀Flat gate valve这种类型的闸阀有带导流孔和不带导流孔之分.带导流孔的平板闸阀能通球清管,不带导流孔的平板闸阀只能用作管路上的启闭装置3-01蝶阀Butterfly valve启闭件(蝶板)绕固定轴旋转的阀门3-02中线蝶阀Center line-type butterfly valve蝶板的回转中心(即阀门轴中心)位于阀体的中心线和蝶板的密封截面上的蝶阀3-03单偏心蝶阀Single-eccentric center butterfly vale蝶板的回转中心(即阀门轴中心)位于阀体的中心线上且与蝶板密封面形成一个尺寸偏置的蝶阀3-04双偏心蝶阀Double-eccentric center butterfly valve蝶板的回转中心(即阀门轴中心)与蝶板密封截面形成一个尺寸偏置,并与阀体中心线形成另一个尺寸偏置的蝶阀3-05三偏心蝶阀Three-eccentric center butterfly valve蝶板的回转中心(即阀门轴中心)与蝶板密封面形成一个尺寸偏置,并与阀体中心线形成另一个尺寸偏置;阀体密封面中心线与阀座中心线(即阀体中心线)形成一个角偏置的阀门4-01旋转阀Rotary valve启闭件沿阀座密封曲面轴心作相对旋转运动的阀门4-02球阀Ball valve启闭件(球体)绕垂直于通路的轴线旋转的阀门4-03浮动球阀Float ball valve球体不带有固定轴的球阀4-04固定球球阀Fixed ball valve球体带有固定轴的球阀4-05弹性球球阀Flexible ball valve球体上开有弹性糟的球阀4-06旋塞阀Cock,plug启闭件(塞子)绕其轴线旋转的阀门4-07紧定式旋塞阀Clampyte plug valve塞体内不带填料,塞子与塞体密封面的密封依靠拧紧旋塞下面的螺母来实现的旋塞阀4-08填料式旋塞阀Cland packing plug valve采用填料密封的旋塞阀4-09自闭式旋塞阀Self-sealing plug valve塞子与塞体间的密封主要依靠介质本身的压力来实现的旋塞阀4-10油封式旋塞阀Lubricated plug valve采用油脂密封的旋塞阀4-11旋柱阀Cock,plug启闭件(圆柱形塞子)绕其轴线旋转的阀门5-01挡板阀Baffler valve启闭件(挡板)在阀座密封面上到阀座密封面以外作相对运动,但又不穿过阀座密封面的阀门5-02截止阀Globe valve, stop valve启闭件(阀瓣)由阀杆带动,沿阀座(密封面)轴线作升降运动的阀门5-03上螺纹阀杆截止阀Outside screw stem stop valve阀杆螺纹在壳体外面的截止阀5-04下螺纹阀杆截止阀Inside screw stem stop valve阀杆螺纹在壳体内的截止阀5-05直通式截止阀Globe valve介质的进出口两个通道在同一方向上,呈180°的截止阀5-06角式截止阀Angle pattern globe valve介质的进出口两个通道呈90°的截止阀5-07三角截止阀Three way stop valve具有三个通道的截止阀5-08直流式截止阀Oblique type globe valve阀杆和通道成一定角度的截止阀5-09柱塞式截止阀Plunger type globe valve柱塞式截止阀是常规截止阀的变形.其阀瓣和阀座是按柱塞的原理设计的;把阀瓣设计成柱塞,阀座设计成套环,靠柱塞和套环的配合实现密封5-10针形截止阀Needle globe valve阀座孔的尺寸比公称通径小的截止阀6-01节流阀Throttle valve通过启闭件(阀瓣)改变通路截面积以调节流量.压力的阀门6-02勾形阀瓣节流阀Trench type disc throttle valve常用于深冷装置中的膨胀阀6-03窗形阀瓣节流阀Window type disc throttle valve适用于公称通径较大的节流阀6-04塞形阀瓣节流阀Plug disc throttle valve适用于中.小口径的节流阀7-01止回阀Check valve,Non-reture valve启闭件(阀瓣)靠介质作用力,自动阻止介质逆流的阀门7-02旋启式止回阀Swing check valve阀瓣绕体腔内固定轴作旋转运动的止回阀7-03单瓣旋启式止回阀Single disc swing check valve只有一个阀瓣的旋启式止回阀7-04多瓣旋启式止回阀Multi-disc swing check valve具有二个以上阀瓣的旋启式止回阀7-05升降式止回阀Lift check valve阀瓣垂直于阀座孔轴线作升降运动的止回阀7-06底阀Foot valve安装在泵吸入管端,以保证吸入管内被水充满的止回阀7-07弹簧载荷升降式止回阀Spring-loaded lift check valve该阀不仅能降低水击压力,而且流道通畅,流阻很小7-08弹簧载荷环形阀瓣升降式止回阀Spring-loaded annular disc lift check valve 该阀与通常结构的升降式止回阀相比,阀瓣行程更小,加之弹簧载荷的作用,使其关闭迅速,因此,更利于降低水击压力7-09多环形流道升降式止回阀Multi-annulus lift check valve该阀具有最小的阀瓣行程,因此其关闭更为迅速7-10蝶式止回阀Butterfly swing check valve形状与蝶瓣相似,起阀瓣绕固定轴(无摇杆)作旋转运动的止回阀7-11管道式止回阀Line check valve阀瓣沿着阀体中心线滑动的止回阀.该阀体积小,重量轻,加工工艺性好,但流阻系数比旋启式止回阀略大7-12空排止回阀No-load running check valve这是一种特殊用途的止回阀,用于锅炉给水泵的出口,以防止介质倒流及起空排作用7-13缓闭止回阀Dashpot check valve在旋启式止回阀或升降式止回阀上设置缓冲装置,形成缓闭止回阀,这种止回阀能有效地防止水击7-14隔膜式止回阀Diaphragm type check valve该阀是止回阀的一种新的结构形成,尽管它的使用受到温度和压力等的限制,但其防止水击压力比传统的旋启式止回阀小得多7-15锥形隔膜式止回阀Tapered diaphragm type check valve该阀对夹安装在管道两法兰之间,其关闭速度极为迅速7-16环形编织隔膜式止回阀Annular woven diaphragm type check valve该阀采用了褶皱的环状橡胶隔膜,关闭速度极快,但其使用范围通常受压差(△p〈1MPa)和温度(t〈70°C)的限制7-17球形止回阀Ball check valve胶球(单球与多球)在介质作用下,在球罩内沿阀体中心线方向作来回短行程滚动,以实现其开启和关闭动作8-01安全阀Safety valve一种自动阀门,它不借助任何外力,而是利用介质本身的力来排出额定数量的流体,以防止系统内压力超过预定的安全值,当压力恢复正常后,阀门再行关闭并阻止介质继续流出8-02重锤式安全阀Weighted safety valve用杠杆和重锤来平衡阀瓣压力的止回阀.这种结构只能用在固定设备上,其重锤的重量一般不应超过60kg8-03弹簧式安全阀Spring type safety valve利用压缩弹簧的力来平衡阀瓣的压力并使其密封的安全阀.这类安全阀的弹簧作用力一般不应超过20000N8-04脉冲式安全阀Pulse type safety valve该阀把主阀和辅阀设计在一起,通过辅阀的脉冲作用带动主阀动作,这种结构通常用于大口径.大排量及高压系统8-05微启式安全阀Low lift safety valve阀瓣开启高度为阀座喉径的1/40~1/20的安全阀8-06全启式安全阀Fall lift safety valve阀瓣开启高度等于或大于阀座喉径的1/4的安全阀8-07全封闭式安全阀All sealed bonnet tgpe safety valve开启排放时,介质不会向外界泄漏,而是全部通过排泄管排放掉.这种结构适用于易燃.易爆.有毒介质8-08半封闭式安全阀Half sealed bonnet type safety valve开启排放时,介质一部分通过排泄管排掉,而另一部分从阀盖与阀杆的配合处向外泄漏.这种结构适用与一般的蒸气和对环境无污染的介质8-09敞开式安全阀Exposed type safety valve开启排放时,介质直接由阀瓣上方排放,这种安全阀适用于对环境污染无要求的场合8-10直接载荷式安全阀Direct loaded safdty valve直接用机械载荷如重锤.杠杆重锤或弹簧来克服由阀瓣下介质压力所产生作用力的安全阀8-11带辅助装置的安全阀Assisted safety valve该安全阀借助一个动力辅助装置,可以在低于正常的开启压力下开启.即使辅助装置失灵,此类阀门应仍能满足标准的要求8-12带补充载荷的安全阀Supplementary loaded safety valve该安全阀在其进口处压力达到开启压力前始终保持有一增强密封的附加力.该附加力(补充载荷)可由外来的能源提供,而在安全阀达到开启压力时应可靠的释放.其大小应这样设定,即假定该附加力未释放时,安全阀仍能在进口压力不超过国家法规规定的开启压力百分数的前提下达到额定排量8-13先导式安全阀Pilot operated safety valve一种依靠导阀来驱动或控制的安全阀.该导阀本身应是符合标准要求的直接载荷式安全阀8-14杠杆式安全阀Lever and weight loaded safety valve利用杠杆将作用力传递到阀瓣上的安全阀8-15波纹管平衡式安全阀Bellows seal balance safety valve利用波纹管平衡背压的作用,以保持开启压力不变的安全阀8-16双联弹簧式安全阀Duplex safety valve将两个弹簧式安全阀并联,具有同一进口的安全阀组9-01减压阀Pressure reducing valve通过启闭件的节流,将介质压力降低,并利用介质本身能量,使阀后的压力自动满足预定要求的阀门9-02活塞式减压阀Piston reducing vakve采用活塞作传感元件,带动阀瓣运动的减压阀9-03薄膜式减压阀Diaphragm reducing valve采用薄膜作传感元件,带动阀瓣运动的减压阀9-04气包式减压阀Air bag type reducing valve依靠阀后介质进入气包内的压力来平衡阀的压力的减压阀9-05弹簧薄膜式减压阀Spring diaphragm reducing valve采用弹簧和薄膜作传感件来带动阀瓣升降运动的减压阀9-06波纹管式减压阀Bellows seal reducing valve采用波纹管机构来带动阀瓣升降运动的减压阀9-07杠杆式减压阀Lever reducing calve采用杠杆机构来带动阀瓣升降运动的减压阀9-08定值减压阀Fixed pressure reducing valve出口压力保持定值的减压阀9-09定比减压阀Proportionging pressure reducing valve出口压力与进口压力或某个参考压力保持一定比例的减压阀9-10定差减压阀Fixed differential reducing valve出口压力与进口压力或某个参考压力保持一定压力差的减压阀9-11直接作用式减压阀Direct-acting reducing valve利用出口压力变化,直接控制阀瓣运动的减压阀9-12先导式减压阀Pilot-operated reducing valve由主阀和导阀组成,出口压力变化通过放大,控制主阀动作的减压阀9-13先导式减压阀主阀Main valve在先导式减压阀中,受导阀控制对流通介质起调控作用的阀9-14先导式减压阀导阀Pilot valve在先导式减压阀中,起控制主阀动作的前置阀9-15正向作用式减压阀Direct accing reduding valve进口介质对阀瓣的作用力与阀瓣升起方向一致的减压阀9-16反向作用式减压阀Reverse acting reducing valve进口介质对阀瓣的作用力与筏瓣升起方向相反的减压阀转子泵卡斯特红酒9-17卸荷式减压阀Balanced reducing valve进口介质对阀瓣的作用力接近或达到平衡的减压阀10-01蒸汽疏水阀Steam trap自动排放凝结水并阻止蒸汽泄漏的阀门10-02机械型蒸汽疏水阀Mechanical steam trap由凝结水位变化驱动启闭件,使其完成阻汽排水动作的疏水阀10-03浮球式疏水阀Ball float steam trap利用在凝结水中浮动的空心球,带动启闭件动作的疏水阀10-04自由浮球式蒸汽疏水阀Free-ball float steam trap由壳体内凝结水的液位变化导致启闭件(自由浮球)的开关动作.该阀能够排饱和水,且能连续排放凝结水10-05杠杆浮球式蒸汽疏水阀Lever-ball float steam trap由壳体内凝结水的液位变化导致启闭件(杠杆浮球)的开关动作.该阀杠杆机构的特点是可以扩大浮力,因此,可以用于超大排量的场合10-06自由半浮球式蒸汽疏水阀Free-semi-ball float steam trap采用能自由活动的半球形浮子(自由半浮球),浮子本身具有阀瓣的机能,是没有铰链.杠杆及连杠机构即能开闭阀口的结构,也是结构最简单的蒸汽疏水阀10-07敞口向下浮子式蒸汽疏水阀Inverted bucket steam trap其浮子的开口向下,由浮子内凝结水的液位变化导致启闭件的开关动作.该阀多数不把阀瓣直接固定在浮子上,而是采用杠杆机构以扩大浮力10-08敞口向上浮子式蒸汽疏水阀Open bucket force steam trap该阀又称为浮桶式蒸汽疏水阀,是利用在凝结水中的浮桶,带动启闭件动作的蒸汽疏水阀10-09热静力型蒸汽疏水阀Hot-statical force steam trap由凝结水温变化驱动启闭件,使其完成阻汽排水动作的疏水阀10-10波纹管式蒸汽疏水阀Bellows seal steam trap该阀是在蛇形管容器内,即在波纹管内封入沸点低.易挥发的液体作为感温元件.在波纹管上固定着阀瓣,随着温度变化,波纹管产生伸缩而启闭的疏水阀10-11膜盒式蒸汽疏水阀Membrane-box steam trap该阀属蒸汽压力式,由凝结水的压力与可变形元件内挥发性液体的蒸汽压力之间的不平衡来驱动启闭件的动作,该阀不会产生气堵10-12双金属片式蒸汽疏水阀Bimetal elements steam trap利用双金属片受热变形,带动启闭件动作的蒸汽疏水阀.该阀不会发生闭塞现象10-13热动力型蒸汽疏水阀Hot-motive force steam trap由凝结水动态特性的变化,驱动启闭件,使其完成阻汽排水动作的疏水阀10-14圆盘式蒸汽疏水阀Dise steam teap利用蒸汽和凝结水的不同热力性质,及其静压和动压的变化,使阀片动作的蒸汽疏水阀10-15脉冲式蒸汽疏水阀Impulse steam trap利用蒸汽在两级节流中的二次蒸发,导致蒸汽和凝结水的压力变化,而使启闭件动作的蒸汽疏水阀10-16迷宫或孔板式蒸汽疏水阀Orifice steam trap该类形式的蒸汽疏水阀是由节流孔控制凝结水的排放量,并使热凝结水变化,而减少蒸汽的流出11-01隔膜阀Diaphragm valve启闭件(隔膜)由阀杆带动,沿阀杆轴线作升降运动,并将动作机构与介质隔开的阀门11-02截止式隔膜阀Globe diaphragm valve阀体与截止阀阀体形状相似的隔膜阀11-03屋脊式隔膜阀Weir diaphragm valve阀体流道中以屋脊形结构与隔膜构成密封副的隔膜阀11-04榨板式隔膜阀Wedge diaphragm valve闸瓣与楔式闸阀的单闸板形状相似的隔膜阀12-01多用阀Multipurpose valve具有多种用途的阀门12-02截止止回阀Serew-down stop check valve一种可以起截止和止回两种作用的阀门,该阀适用于安装位置受到限制的场合12-03截止止回节流阀Serew-down stop check and throttle valve一种可起截止.止回.节流作用的三用阀.该阀大量使用在油井并注水装置上12-04截止止回安全阀Serew-down stop check and safety valve一种起截止.止回.安全作用的三用阀12-05止回球阀Check-ball valve一种可以做止回和球阀的两用阀门。
国开液压与气压传动
国开液压与气压传动液压传动是一种通过液体传递能量来实现机械运动的传动方式。
它利用液压泵将机械能转化为液压能，并通过液压马达或液压缸将液压能转化为机械能。
原理液压传动的工作原理基于 Pascal 定律，即液体在受力时会均匀传递压力。
液压系统由液压泵、液压马达（或液压缸）以及连接管道和控制阀组成。
液压泵通过产生高压液体，将机械能转化为液压能。
液压能通过管道传递到液压马达（或液压缸），驱动机械部件实现运动。
组成液压传动主要由以下关键元件组成：液压泵：负责将机械能转化为液压能的装置。
液压马达：将液压能转化为机械能，驱动机械部件运动的装置。
液压缸：将液压能转化为线性机械能的装置。
连接管道：用于输送液体的管道系统。
控制阀：用于调节液压系统中液体的流量、压力和方向等参数的装置。
工作过程液压传动的工作过程可以简单描述如下：液压泵将液体从低压区域吸入并压缩，产生高压液体。
高压液体通过连接管道流入液压马达（或液压缸）。
液压马达（或液压缸）受到高压液体的作用，将液压能转化为机械能。
机械能驱动机械部件运动，完成相应的工作任务。
液体从液压马达（或液压缸）流回低压区域，形成回路，循环使用。
液压传动具有传递力矩大、稳定性好、调速范围广等特点，广泛应用于各种机械设备中。
气压传动是一种常见的工业传动方式，它利用压缩空气作为能源，将能量转化为机械动力。
气压传动具有结构简单、安全可靠、响应速度快等优点，被广泛应用于各个领域。
原理气压传动的基本原理是利用气体的压缩性质来实现能量转换。
通过压缩机将空气压缩成高压气体，然后将高压气体传送到气缸中，推动活塞产生往复运动。
气缸通过连杆与其他机械部件相连接，从而将气压能转化为机械能。
组成气压传动主要由以下几个组件组成：压缩机：用于将周围空气压缩成高压气体的装置。
气缸：接受高压气体并产生往复运动的装置。
活塞：在气缸内部运动的部件，通过推动该活塞实现气压能的转换。
连杆：将活塞与其他机械部件连接的部件，将气缸的往复运动转换为其他形式的运动。
液压系统外文文献翻译、中英文翻译、外文翻译
本科生毕业设计 (论文)外文翻译原文标题液压系统译文标题HYDRAULIC SYSTEMS作者所在系别作者所在专业作者所在班级作者姓名作者学号指导教师姓名指导教师职称完成时间2017 年 4 月15教务处制控制阀控制阀是操作者可访问的阀，用于引导系统内的流体流动以操作机器或其附件。
通过巧妙地使用控制阀，操作员可以调节液压缸的速度和运行。
注意：液压控制应平稳运行，以消除引起机器机械部件快速磨损和破坏的冲击运动。
执行机构（a）旋转叶片液压致动器，（b）线性液压致动器。
通过输入控制信号改变控制阀的位置，允许通过通道流动以操作致动器。
当致动器移动时，其运动沿反馈路径传递，从而抵消控制阀的原始运动。
因此，致动器的输出运动与输入控制运动成比例。
带反馈的旋转风门执行机构线性执行器（RAM）带反馈SPOOL阀门关闭和方向控制阀芯阀直接流到系统的各个部件，并可通过手柄，先导压力信号，电磁螺线管，电动马达和机械凸轮来操作。
用于滑动滑阀方向阀的典型应用是将流体控制到双作用液压缸，其在一个方向上移动时需要在活塞的一侧上的压力下的流体，而另一侧连接到排出管线。
在上述滑阀中，三位置阀芯通过反馈连杆保持在其位置。
在中央位置，所有部件都被锁定。
因此，显而易见的是，当阀芯保持中心时，气缸不能被轻便。
相对于各种端口移动阀芯的位置控制缺陷的方向，如果阀芯向左移动，高压油将通过阀门流到执行器的左侧。
同时，线性执行器的右侧将连接到排气口。
从而将线性致动器向右移动。
一旦致动器已经移动与控制运动成正比的一定量，线轴将自动地通过反馈链路移动到中心。
累积器描述液压蓄能器并解释其目的。
压力蓄能器用于需要储存压力能量以满足需求浪涌的液压系统中，它们还用于吸收液压冲击载荷，并在泵停止时保持压力时补偿小的内部泄漏。
最常见的蓄能器形式包括含有充气和加压柔性气囊的钢壳。
通过特殊阀将气囊预充到所需压力，然后密封以防止气体泄漏。
压力下的液压油进入蓄能器，压缩气囊，直到达到平衡。
液压系统和气压系统外文文献翻译、中英文翻译
液压系统和气压系统外文文献翻译、中英文翻译Hydraulic system and Peumatic SystemHui-xiong wan1,Jun Fan2Abstract:Hydraulic system is widely used in industry, such as stamping, grinding of steel type work and general processing industries, agriculture, mining, space technology, deep sea exploration, transportation, marine technology, offshore gas and oil exploration industries, in short, Few people in their daily lives do not get certain benefits from the hydraulic technology. Successful and widely used in the hydraulic system's secret lies in its versatility and ease of maneuverability. Hydraulic power transmission mechanical systems as being not like the machine geometry constraints, In addition, the hydraulic system does not like the electrical system, as constrained by the physical properties of materials, it passed almost no amount of power constraints.Keywords: Hydraulic system,Pressure system,FluidThe history of hydraulic power is a long one, dating from man’s prehistoric efforts to harness the energy in the world around him. The only source readily available were the water and the wind—two free and moving streams.The watermill, the first hydraulic motor, was an early invention. One is pictured on a mosatic at the Great Palace in Byzantium, dating from the early fifth century. The mill had been built by the Romans. But the first record of a watermill goes back even further, to around 100BC, and the origins may indeed have been much earlier. The domestication of grain began some 5000 years before and some enterprising farmer is bound to have become tired of pounding or grinding the grain by hand. Perhaps,in fact, the inventor were some farmer’s wives. Since the often drew the heavy jobs.Fluid is a substance which may flow; that is, its constituent particles may continuously change their positions relative to one another. Moreover, it offers no lasting resistance to the displacement, however great, of one layer over another. This means that, if the fluid is at rest, no shear force (that is a force tangential to the surface on which it acts) can exist in it.Fluid may be classified as Newtonian or non--Newtonian. In Newtonian fluid there is a linear relation between the magnitude of applied shear stresses and the resulting rate of angular deformation. In non—Newtonian fluid there is a nonlinear relation between the magnitude of applied shear stress and the rate of angulardeformation.The flow of fluids may be classified in many ways, such as steady or non steady, rotational or irrotational, compressible or incompressible, and viscous or no viscous.All hydraulic systems depend on Pascal’s law, such as steady or pipeexerts equal force on all of the surfaces of the container.In actual hydraulic systems, Pas cal’s law defines the basis of results which are obtained from the system. Thus, a pump moves the liquid in the system. The intake of the pump is connected to a liquid source, usually called the tank or reservoir. Atmospheric pressure, pressing on the liquid in the reservoir, forces the liquid into the pump. When the pump operates, it forces liquid from the tank into the discharge pipe at a suitable pressure.The flow of the pressurized liquid discharged by the pump is controlled by valves. Three control functions are used in most hydraulic systems: (1) control of the liquid pressure, （2）controlof the liquid flow rate, and (3) control of the direction of flow of the liquid.Hydraulic drives are used in preference to mechanical systems when(1) powers is to be transmitted between point too far apart for chains or belts; (2) high torque at low speed in required; (3) a very compact unit is needed; (4) a smooth transmission, free of vibration, is required;(5) easy control of speed and direction is necessary; and (6) output speed is varied steplessly.Fig. 1 gives a diagrammatic presentation of the components of a hydraulic installation. Electrically driven oil pressure pumps establish an oil flow for energy transmission, which is fed to hydraulic motors or hydraulic cylinders, converting it into mechanical energy. The control of the oil flow is by means of valves. The pressurized oil flow produces linear or rotary mechanical motion. The kinetic energy of the oil flow is comparatively low, and therefore the term hydrostatic driver is sometimes used. There is little constructional difference between hydraulic motors and pumps. Any pump may be used as a motor. The quantity of oil flowing at any given time may be varied by means of regulating valves( as shown in Fig.7.1) or the use of variable-delivery pumps.The application of hydraulic power to the operation of machine tools is by no means new, though its adoption on such a wide scale as exists at present is comparatively recent. It was in fact in development of the modern self-contained pump unit that stimulated the growth of this form of machine tool operation.Hydraulic machine tool drive offers a great many advantages. One of them is that it can give infinitely-variable speed control over wide ranges. In addition, they can change the direction ofdrive as easily as they can vary the speed. As in many other types of machine, many complex mechanical linkages can be simplified or even wholly eliminated by the use of hydraulics.The flexibility and resilience of hydraulic power is another great virtue of this form of drive. Apart from the smoothness of operation thus obtained, a great improvement is usually found in the surface finish on the work and the tool can make heavier cuts without detriment and will last considerably longer without regrinding.Hydraulic and pneumatic systemThere are only three basic methods of transmitting power:electrical,mechanical,and fluid power.Most applications actually use a combination of the three methods to obtain the most efficient overall system. To properly determine which principle method to use,it is important to know the salient features of each type. For example, fluid systems can transmit power more economically over greater distances than can mechanical types. However, fluid systems are restricted to shorter distances than are electrical systems.Hydraulic power transmission system are concerned with the generation, modelation, and control of pressure and flow，and in general such systems include:1.Pumps which convert available power from the prime mover to hydraulic power at the actuator.2.Valves which control the direction of pump-flow, the level of power produced, and the amount of fluid-flow to the actuators. The power level is determined by controlling both the flow and pressure level.3.Actcators which convert hydtaulic power to usable mechanical power output at the point required.4.The medium, which is a liquid, provides rigid transmission and control as well as lubrication of componts, sealing in valves, and cooling of the system.5.Conncetots which link the various system components, provide power conductors for the fluid under pressure, and fluid flow return to tank(reservoir).6.Fluid storage and conditioning equipment which ensure sufficient quality and quantity as well as cooling of the fluid.Hydraulic systems are used in industrial applications such as stamping presses, steel mills, and general manufacturing, agricultural machines, mining industry,aviation, space technology, deep-sea exploration, transportion, marine technology, and offshore gas and petroleum exploration. In short, very few people get through a day of their lives without somehow benefiting from the technology of hydraulicks.The secret of hydraulic system’s success and widespread use is its versatility and manageability. Fluid power is not hindered by the geometry of the machine as is the case in mechanical systems. Also, power can be transmitted in almost limitless quantities because fluid systems are not so limited by the physical limitations of materials as are the electrical systems. For example, the performance of an electromangnet is limited by the saturation limit of steel. On the other hand, the power limit of fluid systems is limited only by the strength capacity of the material.Industry is going to depend more and more on automation in order to increase productivity. This includes remote and direct control of production operations, manufacturing processes, and materials handling. Fluid power is the muscle of automationbecause of advantages in the following four major categories.1.Ease and accuracy of control. By the use of simple levers and push buttons, the operator of a fluid power system can readily start, stop, speed up or slow down, and position forces which provide any desired horsepower with tolerances as precise as one ten-thousandth of an inch.2.Multiplication of force. A fluid power system(without using cumbersome gears, pulleys, and levers) can multiply forces simply and efficiently from a fraction of an ounce to several hundred tons of output.3.Constant force or torque. Only fluid power systems are capable of providing contant force or torque regardless of speed changes. This is accomplished whether the work output moves a few inches per hour, several hundred inches per minute, a few revolutions per hour, or thousands of revolutions per minute.4.Simplicity, safely, economy. In general, fluid power systems use fewer moving parts than comparable mechanical or electrical systems. Thus, they are simpler to maintain and operate. This, in turn, maximizes safety, companctness, and reliability. For example, a new power steering control designed has made all other kinds of power systems obsolete on many off-highway vehicles. The steering unit consists of a manually operated directional control valve and meter in a single body. Because the steering unit is fully fluid-linked, mechanical linkages, universal joints, bearings, reduction gears, etc, are eliminated. This provides a simple, compact system. In addition, very little input torque is required to produce the control needed for the toughest applications. This is important where limitations of control space require a small steering wheel and it becomes necessary to reduce operatot\r fatique.Additonal benefits of fluid power systems include instantly reversible motion, automatic protection against overloads, and infinitely variable speed control. Fluid power systems also have the highest horsepower per weight ratio of any known power source. In spite of all these highly desirable features of fluid power, it is not a panacea for all power transmission problems. Hydraulic systems also have some drawbacks. Hydraulic oils are messy, and leakage is impossible to completely eliminate. Also, most hydraulic oils can cause fires if an oils occurs in an area of hot equipment.Peumatic SystemPneumatic systems use pressurized gases to tansmit and control power. A s the name implies, pneumatic systems typically use air(rather than some other gas) as the fluid medium because air is a safe, low-cost, and readily available fluid. It is particularly safe in environments where an electrical spark could ignite leaks from system components.In pneumatic systems ,compressors are used to compress and supply the necessary quantities of air. Compressors are typically of the piston, vane or screw type. Basically a compressor increases the pressure of a gas by reducing its volume as described by the perfect gas laws.Pneumatic systems normally use a large centralized air compressor which is considered to be an infinite air source similar to an electrical system where you merely plug into an electrical outlut for electricity. In this way, pressurized air can be piped from one source to various locations throughout an entire industrial plant. The air then flows through a pressue regulator which redeces the pressure to the desired level for the particular circuit application. Because air is not a good lubircant（contains about 20% oxygen）, pneumaticssystems required a lubricator to inject a very fine mist of oil into the air discharging from the pressure regulator. This prevents wear of the closely fitting moving parts of pneumatic components.Free air from the atmosphere contains varying amounts of moisure. This moisure can be harmful in that it can wash away lubricants and thus cause excessive wear and corrosion. Hence ,in some applications ,air driers are needed to remove this undesirable moisture. Since pneumatics systems exhaust directly into the atmosphere, they are capable of generating excessive noise. Therefore, mufflers are mounted on exhaust ports of air valves and actuators to reduce noise and prevent operating personnel from injury resulting not only from exposure to noise but also from high-speed airborne particles.There are several reasons for considering the use of pneumatic systems instead of hydraulic systems. Liquids exhibit greater inertia than do gases. Therefore, in hydraulic systems the weight of oil is a potential problem when accelerating and decelerating actuators and when suddenly opening and closing valves. Due to Newton’s law of motion(force equals mass multiplied by acceleration), the force required to accelerate oil is many times greater than that required to accelerate an equal volume of air. Liquids also exhibit greater viscosity than do gases. This results in larger frictional pressure and power losses. Also ,since hydraulic systems use a fluid foreign to the atmosphere, they require special reservoirs and noleak system designs. Pneumatic system use air which is exhausted directly back into the surrounding environment. Generally speaking, pneumatic systems are less expensive than hydraulic systems.However, because of the compressibility of air, it isimpossible to obtain precise controlled actuator velocities with pneumatic systems. Also, precise positioning control is not obtainable. While pneumatics pressures are quite low due to compressor design limitations(less than 250 psi), hydraulic pressures can be as high as 10000 psi. Thus, hydraulics can be high-power systems, whereas pneumatics are confined to low-power applications. Industrial applications of pneumatics systems are growing at a rapid pace. Typical examples include stamping, drilling, hoist, punching, clamping, assembling, riveting, materials handling, and logic controlling operations.液压系统和气压系统万辉雄1，范军2摘要：液压系统在工业中应用广泛，例如冲压、钢类工件的磨削及一般加工业、农业、矿业、航天技术、深海勘探、运输、海洋技术，近海天然气和石油勘探等行业，简而言之，在日常生活中很少有人不从液压技术得到某些益处。
剪式小型举升机机械设备外文文献翻译、中英文翻译、外文翻译
剪式小型举升机机械设备外文文献翻译、中英文翻译、外文翻译is to make it more efficient。
XXX is one of the most commonly used types of lifting machines。
XXX。
warehousing。
n。
and logistics。
XXX uses a scissor-like mechanism to raise and lower the platform。
It is mainly composed of a platform。
scissor legs。
hydraulic system。
and control system。
The platform can move up and down XXX。
and the height can be adjusted according to the needs of the work.In recent years。
with the development of technology。
XXX。
higher lifting capacity。
and XXX。
some scissor lifts are equipped with n devices。
overload n devices。
XXX.In n。
the design of the XXX adjustable handrails。
foot pedals。
and XXX also makes it easy to move and transport。
XXX.In n。
XXX。
XXX efficient。
safer。
and XXX to use。
which will XXX the development of the industry.Nowadays。
XXX。
there are also several successful designsof portable lifting machines。
卡套式管接头 液压传动术语中英文对照共14页word资料
卡套式管接头液压传动术语中英文对照卡套式管接头：液压传动术语中英文对照2010-09-12问题：本人准备参加研究生复试，笔试要考专业英语，求液压与气压传动术语与元件的中英文对照，谢谢最佳答案：没有最佳答案其他回答1：不好意思，文献没有。
只有这些词汇。
液压专业英语词汇acceptable conditions许用工况actual conditions实际工况actual force实际输出力air contamination空气污染air consumption耗气量air conditioner unit空气处理单元air filter空气过滤器adjustable restrictive valve可调节流阀amplifier放大器amplitude ratio幅值比analogue amplifier模拟放大器anti-corrosive quality抗腐蚀性automatic cycle自动循环axial piston pump轴向柱塞泵back pressure背压bladder accumulator气囊式蓄能器bleed line放气管路bonded washer组合垫圈breakout pressure启动压力butterfly valve蝶阀cartridge valve插装阀cavitation气穴charge pressure充油压力check valve单向阀circle循环circuit diagram回路图clamper管卡closed circuit闭式回路collapse pressure压溃压力compensator避震喉composite seal复合密封件continuous working conditions连续工况control of pump泵的控制control console操作台control panel控制屏cooler冷却器counterbalance valve平衡阀cracking pressure开启压力cushioning缓冲cylinder缸cycling speed循环速度De-energizing of solenoid电磁铁释放density密度diaphragm valve膜片阀differential circuit差动回路differential cylinder差动缸differential pressure instrument压差计digital amplifier数字放大器direction of rotation旋转方向directly operated type直动式displacement排量dither颤振double-acting cylinder双作用缸Double throttle check valve双单向节流阀drain line泄油管路drift漂移drive shaft coupling联轴器dwell phase停止工步duplex filter双筒过滤器efficiency效率effective filtration area有效过滤面积elastomer seal弹性密封件elbow弯头electrical pressure transducer压力传感器external leakage外泄漏extend stroke外伸行程filter pressure drop过滤器压降fitting；connection接头fixed restrictive valve固定节流阀flared fitting扩口式接头flash point闪点flexible hose软管flange connection法兰接头flange mounting法兰安装flow-combining valve集流阀flow control valve流量控制阀flow control circuit调速回路flow divider valve分流阀flow gain流量增益flow limit流量极限flow line管路flow meter流量计flow pass流道flow rate流量Flow valve流量阀flower factor流量系数foot mounting底座安装force输出力four-way valve四通阀free position自由位frequency response频率响应function diagram功能图gate valve闸阀gear pump齿轮泵global(ball)valve球阀graphical symbol图形符号heat exchanger热交换器heater加热器hydraulic lock液压锁紧hydraulic motor液压马达hydraulic power流体传动hydraulics液压技术hydrodynamics液力技术hydropneumatics气液技术hysteresis滞环hydraulic amplifier液压放大器hydraulic controlled type液控式instantaneous conditions瞬态工况internal leakage内泄漏inlet pressure进口压力induced pressure负载压力kinematic viscosity运动粘度laminar flow层流lap遮盖leakage泄漏limited conditions极限工况linearity线性度linear region线性区liquid contamination液体污染liquid level measuring instrument液位计lubricator油雾气manually operated type手动式man ifold block油路块mechanically controlled type机械控制式mechanical seal机械密封meter-in circuit进口节流回路meter-out circuit出口节流回路Manifold block集成块needle valve针阀neutral position中位nitrile butadiene rubber；NBR丁腈橡胶noise level噪声等级nominal filtration rating公称过滤精度nominal pressure公称压力nozzle flapper喷嘴挡板null bias零偏null drift零漂null(quiescent)leakage零位内泄漏one-way restrictive valve单向节流阀opening开口open circuit开式回路operating conditions运行工况operating pressure运行压力outlet pressure出口压力over lap正遮盖override pressure调压偏差override control优先控制packing seal填料密封peak pressure峰值压力phase工步phase lag相位移Pilot valve先导阀pilot pressure控制压力pilot-controlled check valve液控单向阀pilot-operated type先导式Pilot operated check valve液控单向阀piston pump柱塞泵pilot line控制管路pipe-work管路布置piston seal活塞密封polytetrafluoroethene；PTFE聚四氟乙烯poppet valve锥阀portable particle counter便携式颗粒检测仪port油口Position feedback位置反馈power station液压泵站pre-charge pressure充气压力pressure control circuit压力控制回路pressure drop；differential pressure压降pressure gauge压力表Pressure relief valve压力溢流阀pressure switch压力开关pressure time diagram压力-时间图pressure relief valve压力控制阀pressure relief valve溢流阀pressure reducing valve减压阀Progressive flow渐增流量Proportional valve比例阀proof pressure耐压试验压力pulse generator脉冲发生器quick release coupling快换接头radial seal径向密封rapid advance phase快进工步rapid return phase快退工步rated conditions额定工况rated flow额定流量rated pressure额定压力rear end无杆端Rectifier plate节流板reducer fitting异径接头replenishing line补液管路reservoir fluid capacity油箱容量resolution分辨率retract stroke内缩行程return line回油管路repeat ability重复性reproducibility复现性rigid tube硬管ripple波动rod end有杆端rod seal活塞杆密封rotary seal旋转密封Rotary knob旋钮rust protection防锈性safety circuit安全回路sandwich valve叠加阀Sandwich plate valve叠加阀sealed reservoir闭式油箱sensor传感器sequence valve顺序阀servo-valve伺服阀shut-off valve截止阀shuttle valve梭阀silencer消声器single-acting cylinder单作用缸slide valve滑阀solid contamination固体颗粒污染Solenoid valve电磁阀speed regulator valve调速阀static pressure静压力stickin g液压卡紧steady-state conditions稳态工况stiffness刚度sub-plate底板sub-plate valve板式阀Sub-plate mount板式安装suction pressure吸入压力supply flow供给流量surge pressure冲击压力system pressure系统压力symbols for hydraulic and pneumatic components液压气动元件图形符号symbols for fluid logic devices流体逻辑元件图形符号symbols for logic functions逻辑功能图形符号symmetry对称度synchronizing circuit同步回路telescopic cylinder伸缩缸thermostat温度控制器threshold阈值Throttle valve节流阀transfer function传递函数turbulent flow紊流under lap负遮盖unloading valve卸荷阀valve阀valve element阀芯valve element position阀芯位置variable displacement pump变量泵valve pressure drop阀压降valve polarity阀极性viscosity粘度water content含水量welded fitting焊接式接头wiper seal；scraper防尘圈密封working cycle工作循环working pressure工作压力working phase工作工步working stroke工作行程working line工作管路vane pump叶片泵zero position零位zero lap零遮盖一.阀类分流阀flow divider valve截止阀shut-off valve球阀global(ball)valve针阀needle valve闸阀gate valve膜片阀diaphragm valve蝶阀butterfly valve阀valve底板sub-plate油路块manifold block板式阀sub-plate valve 叠加阀sandwich valve插装阀cartridge valve滑阀slide valve锥阀poppet valve阀芯valve element阀芯位置valve element position 单向阀check valve液控单向阀pilot-controlled check valve 梭阀shuttle valve压力控制阀pressure relief valve溢流阀pressure relief valve顺序阀sequence valve减压阀pressure reducing valve平衡阀counterbalance valve卸荷阀unloading valve流量控制阀flow control valve方向控制阀(directional valve)液压辅件(accessory)普通阀(common valve)Solenoid valve电磁阀Check valve单向阀Cartridge valve插装阀Sandwich plate valve叠加阀Pilot valve先导阀Pilot operated check valve液控单向阀Sub-plate mount板式安装Manifold block集成块Rotary knob旋钮Rectifier plate节流板Servo valve伺服阀Proportional valve比例阀Positi on feedback位置反馈Progressive flow渐增流量De-energizing of solenoid电磁铁释放固定节流阀fixed restrictive valve可调节流阀adjustable restrictive valve单向节流阀one-way restrictive valve调速阀speed regulator valve分流阀flow divider valve集流阀flow-combining valve DDV-direct drive valve直动式伺服阀二、介质类Phosphate ester(HFD-R)磷酸甘油酯Water-glycol(HFC)水-乙二醇Emulsion乳化液Inhibitor缓蚀剂Synthetic lubricating oil合成油三、液压安装工程Abrasion摩擦Argon氩气Butt welding对接焊Contamination污染Creep爬行Dipping process槽式酸洗Extension(活塞杆)缩回Failure失效Flushing冲洗Grout灌浆Inert gas welding惰性气体焊Jog点动Malfunction误动作Nitric acid柠檬酸Passivity钝化Pickling酸洗Retract(活塞杆)伸出Re-circulation循环Socket welding套管焊四、管接头Adjustable fittings/swivel nut旋转接头Banjo fittings铰接式管接头Bite type fittings卡套式管接头Bulkhead fittings长直通管接头Female connector fittings接头螺母Mal stud fittings端直通管接头Reducers extenders变径管接头Tube to tube fittings接管接头union直通接管接头union elbow直角管接头union tee三通管接头union cross四通管接头Weld fittings焊接式管接头五、伺服阀及伺服系统性能参数Dynamic response动态频响DDV-direct drive valve直动式伺服阀NFPA-National Fluid Power Association美国流体控制学会Phase lag相位滞后Nozzle flapper valve喷嘴挡板阀Servo-jet pilot valve射流管阀Dither颤振电流Coil impedance线圈阻抗Flow saturation流量饱和Linearity线形度Symmetry对称性Hysterics滞环Threshold灵敏度Lap滞后Pressure gain压力增益Null零位Null bias零偏Null shift零飘Frequency response频率响应Slope曲线斜坡祝你取得好成绩！历史上的今天：什么是"铜钱头"?！铜钱头2010-09-12铜钱草：铜钱草好养吗?2010-09-12绒线编织花样?求毛线拖鞋花样步骤2010-09-12希望以上资料对你有所帮助，附励志名言3条：：1、世事忙忙如水流，休将名利挂心头。
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(文档含英文原文和中文翻译)中英文资料对照外文翻译液压系统液压传动和气压传动称为流体传动，是根据17世纪帕斯卡提出的液体静压力传动原理而发展起来的一门新兴技术，1795年英国约瑟夫•布拉曼(Joseph Braman,1749-1814)，在伦敦用水作为工作介质，以水压机的形式将其应用于工业上，诞生了世界上第一台水压机。
1905年将工作介质水改为油，又进一步得到改善。
第一次世界大战(1914-1918)后液压传动广泛应用，特别是1920年以后，发展更为迅速。
液压元件大约在 19 世纪末 20 世纪初的20年间，才开始进入正规的工业生产阶段。
1925 年维克斯(F.Vikers)发明了压力平衡式叶片泵,为近代液压元件工业或液压传动的逐步建立奠定了基础。
20 世纪初康斯坦丁•尼斯克(G•Constantimsco)对能量波动传递所进行的理论及实际研究;1910年对液力传动(液力联轴节、液力变矩器等)方面的贡献，使这两方面领域得到了发展。
第二次世界大战(1941-1945)期间,在美国机床中有30%应用了液压传动。
应该指出,日本液压传动的发展较欧美等国家晚了近 20 多年。
在 1955 年前后 , 日本迅速发展液压传动,1956 年成立了“液压工业会”。
近20～30 年间，日本液压传动发展之快，居世界领先地位。
液压传动有许多突出的优点，因此它的应用非常广泛，如一般工业用的塑料加工机械、压力机械、机床等；行走机械中的工程机械、建筑机械、农业机械、汽车等；钢铁工业用的冶金机械、提升装置、轧辊调整装置等；土木水利工程用的防洪闸门及堤坝装置、河床升降装置、桥梁操纵机构等；发电厂涡轮机调速装置、核发电厂等等；船舶用的甲板起重机械（绞车）、船头门、舱壁阀、船尾推进器等；特殊技术用的巨型天线控制装置、测量浮标、升降旋转舞台等；军事工业用的火炮操纵装置、船舶减摇装置、飞行器仿真、飞机起落架的收放装置和方向舵控制装置等。
一个完整的液压系统由五个部分组成，即动力元件、执行元件、控制元件、辅助元件和液压油。
动力元件的作用是将原动机的机械能转换成液体的压力能，指液压系统中的油泵，它向整个液压系统提供动力。
液压泵的结构形式一般有齿轮泵、叶片泵和柱塞泵。
执行元件(如液压缸和液压马达)的作用是将液体的压力能转换为机械能，驱动负载作直线往复运动或回转运动。
控制元件(即各种液压阀)在液压系统中控制和调节液体的压力、流量和方向。
根据控制功能的不同，液压阀可分为压力控制阀、流量控制阀和方向控制阀。
压力控制阀又分为益流阀(安全阀)、减压阀、顺序阀、压力继电器等；流量控制阀包括节流阀、调整阀、分流集流阀等；方向控制阀包括单向阀、液控单向阀、梭阀、换向阀等。
根据控制方式不同，液压阀可分为开关式控制阀、定值控制阀和比例控制阀。
辅助元件包括油箱、滤油器、油管及管接头、密封圈、压力表、油位油温计等。
液压油是液压系统中传递能量的工作介质，有各种矿物油、乳化液和合成型液压油等几大类。
齿轮泵的概念是很简单的，即它的最基本形式就是两个尺寸相同的齿轮在一个紧密配合的壳体内相互啮合旋转，这个壳体的内部类似“8”字形，两个齿轮装在里面，齿轮的外径及两侧与壳体紧密配合。
来自于挤出机的物料在吸入口进入两个齿轮中间，并充满这一空间，随着齿的旋转沿壳体运动，最后在两齿啮合时排出。
在术语上讲，齿轮泵也叫正排量装置，即像一个缸筒内的活塞，当一个齿进入另一个齿的流体空间时，液体就被机械性地挤排出来。
因为液体是不可压缩的，所以液体和齿就不能在同一时间占据同一空间，这样，液体就被排除了。
由于齿的不断啮合，这一现象就连续在发生，因而也就在泵的出口提供了一个连续排除量，泵每转一转，排出的量是一样的。
随着驱动轴的不间断地旋转，泵也就不间断地排出流体。
泵的流量直接与泵的转速有关。
实际上，在泵内有很少量的流体损失，这使泵的运行效率不能达到100％，因为这些流体被用来润滑轴承及齿轮两侧，而泵体也绝不可能无间隙配合，故不能使流体100％地从出口排出，所以少量的流体损失是必然的。
然而泵还是可以良好地运行，对大多数挤出物料来说，仍可以达到93％～98％的效率。
对于粘度或密度在工艺中有变化的流体，这种泵不会受到太多影响。
如果有一个阻尼器，比如在排出口侧放一个滤网或一个限制器，泵则会推动流体通过它们。
如果这个阻尼器在工作中变化，亦即如果滤网变脏、堵塞了，或限制器的背压升高了，则泵仍将保持恒定的流量，直至达到装置中最弱的部件的机械极限(通常装有一个扭矩限制器)。
对于一台泵的转速，实际上是有限制的，这主要取决于工艺流体，如果传送的是油类，泵则能以很高的速度转动，但当流体是一种高粘度的聚合物熔体时，这种限制就会大幅度降低。
推动高粘流体进入吸入口一侧的两齿空间是非常重要的，如果这一空间没有填充满，则泵就不能排出准确的流量，所以PV值(压力×流速)也是另外一个限制因素，而且是一个工艺变量。
由于这些限制，齿轮泵制造商将提供一系列产品，即不同的规格及排量(每转一周所排出的量)。
这些泵将与具体的应用工艺相配合，以使系统能力及价格达到最优。
PEP－II泵的齿轮与轴共为一体，采用通体淬硬工艺，可获得更长的工作寿命。
“D”型轴承结合了强制润滑机理，使聚合物经轴承表面，并返回到泵的进口侧，以确保旋转轴的有效润滑。
这一特性减少了聚合物滞留并降解的可能性。
精密加工的泵体可使“D”型轴承与齿轮轴精确配合，确保齿轮轴不偏心，以防齿轮磨损。
Parkool密封结构与聚四氟唇型密封共同构成水冷密封。
这种密封实际上并不接触轴的表面，它的密封原理是将聚合物冷却到半熔融状态而形成自密封。
也可以采用Rheoseal密封，它在轴封内表上加工有反向螺旋槽，可使聚合物被反压回到进口。
为便于安装，制造商设计了一个环形螺栓安装面，以使与其它设备的法兰安装相配合，这使得筒形法兰的制造更容易。
PEP－II齿轮泵带有与泵的规格相匹配的加热元件，可供用户选配，这可保证快速加温和热量控制。
与泵体内加热方式不同，这些元件的损坏只限于一个板子上，与整个泵无关。
齿轮泵由一个独立的电机驱动，可有效地阻断上游的压力脉动及流量波动。
在齿轮泵出口处的压力脉动可以控制在1％以内。
在挤出生产线上采用一台齿轮泵，可以提高流量输出速度，减少物料在挤出机内的剪切及驻留时间，降低挤塑温度及压力脉动以提高生产率及产品质量。
液压系统的作用就是帮助人类做工。
主要是由执行元件把压力变成转动或往复运动。
液压的原理：它是由两个大小不同的液缸组成的，在液缸里充满水或油。
充水的叫“水压机”；充油的称“油压机”。
两个液缸里各有一个可以滑动的活塞，如果在小活塞上加一定值的压力，根据帕斯卡定律，小活塞将这一压力通过液体的压强传递给大活塞，将大活塞顶上去。
设小活塞的横截面积是S1，加在小活塞上的向下的压力是F1。
于是，小活塞对液体的压强为P=F1/SI, 能够大小不变地被液体向各个方向传递”。
大活塞所受到的压强必然也等于P。
若大活塞的横截面积是S2，压强P在大活塞上所产生的向上的压力F2=PxS2截面积是小活塞横截面积的倍数。
从上式知，在小活塞上加一较小的力，则在大活塞上会得到很大的力，为此用液压机来压制胶合板、榨油、提取重物、锻压钢材等。
液压系统由信号控制和液压动力两部分组成，信号控制部分用于驱动液压动力部分中的控制阀动作。
液压动力部分采用回路图方式表示，以表明不同功能元件之间的相互关系。
液压源含有液压泵、电动机和液压辅助元件；液压控制部分含有各种控制阀，其用于控制工作油液的流量、压力和方向；执行部分含有液压缸或液压马达，其可按实际要求来选择。
在分析和设计实际任务时，一般采用方框图显示设备中实际运行状况。
空心箭头表示信号流，而实心箭头则表示能量流。
基本液压回路中的动作顺序—控制元件（二位四通换向阀）的换向和弹簧复位、执行元件（双作用液压缸）的伸出和回缩以及溢流阀的开启和关闭。
对于执行元件和控制元件，演示文稿都是基于相应回路图符号，这也为介绍回路图符号作了准备。
根据系统工作原理，您可对所有回路依次进行编号。
如果第一个执行元件编号为0，则与其相关的控制元件标识符则为1。
如果与执行元件伸出相对应的元件标识符为偶数，则与执行元件回缩相对应的元件标识符则为奇数。
不仅应对液压回路进行编号，也应对实际设备进行编号，以便发现系统故障。
DIN ISO1219-2标准定义了元件的编号组成，其包括下面四个部分：设备编号、回路编号、元件标识符和元件编号。
如果整个系统仅有一种设备，则可省略设备编号。
实际中，另一种编号方式就是对液压系统中所有元件进行连续编号，此时，元件编号应该与元件列表中编号相一致。
这种方法特别适用于复杂液压控制系统，每个控制回路都与其系统编号相对应与机械传动、电气传动相比，液压传动具有以下优点：1、液压传动的各种元件，可以根据需要方便、灵活地来布置。
2、重量轻、体积小、运动惯性小、反应速度快。
3、操纵控制方便，可实现大范围的无级调速（调速范围达2000：1）。
4、可自动实现过载保护。
5、一般采用矿物油作为工作介质，相对运动面可自行润滑，使用寿命长。
6、很容易实现直线运动。
7、很容易实现机器的自动化，当采用电液联合控制后，不仅可实现更高程度的自动控制过程，而且可以实现遥控。
液压系统的缺点：1、由于流体流动的阻力和泄露较大，所以效率较低。
如果处理不当，泄露不仅污染场地，而且还可能引起火灾和爆炸事故。
2、由于工作性能易受到温度变化的影响，因此不宜在很高或很低的温度条件下工作。
3、液压元件的制造精度要求较高，因而价格较贵。
4、由于液体介质的泄露及可压缩性影响，不能得到严格的传动比。
5、液压传动出故障时不易找出原因；使用和维修要求有较高的技术水平。
在液压系统及其系统中，密封装置用来防止工作介质的泄漏及外界灰尘和异物的侵入。
其中起密封作用的元件，即密封件。
外漏会造成工作介质的浪费，污染机器和环境，甚至引起机械操作失灵及设备人身事故。
内漏会引起液压系统容积效率急剧下降，达不到所需要的工作压力，甚至不能进行工作。
侵入系统中的微小灰尘颗粒，会引起或加剧液压元件摩擦副的磨损，进一步导致泄漏。
因此，密封件和密封装置是液压设备的一个重要组成部分。
它的工作的可靠性和使用寿命，是衡量液压系统好坏的一个重要指标。
除间隙密封外，都是利用密封件，使相邻两个偶合表面间的间隙控制在需要密封的液体能通过的最小间隙以下。
在接触式密封中，分为自封式压紧型密封和自封式自紧型密封（即唇形密封）两种。
液压系统的三大顽疾1、发热由于传力介质（液压油）在流动过程中存在各部位流速的不同，导致液体内部存在一定的内摩擦，同时液体和管路内壁之间也存在摩擦，这些都是导致液压油温度升高的原因。
温度升高将导致内外泄漏增大，降低其机械效率。