毕业设计（论文）-液压传输-英语翻译.docVIP

HYDRAULIC TRANSMISSION For many years a hydraulic system was considered the result of plumbing together a number of computers.also ,a hydraulic system has been considered merely the source of powder for control servos. Each of these concepts can lead to basic errors. Following either of these guide lines can result in systems which are inadequate ,unable ,or a combination of two. Form an operational standpoint,any hydraulic system can be devided into four logical segments:The power input system,the power transmission system ,the control devices and the power output portion .the power input segment usually considers of pumps and accumulators.the power transmission system includes tubing,tubing connectorss,swivel joints and flexible hose. Flow control valves ,pressure control valves ,and relive valves make up the control elements. The power output portion usually consists of rotary and oscillstory motors or linear actuators.Because almost all prectical hydraulic systems can be divided into thesr same four basic segments,they will be considered in detail later. Paralleling the improvement in hydraulic fluids and other materials has been an increase in the complexity and sophistication od hydraulic systems. Most early hydraulic systems were no more complex than the system in an automobile hydraulic jack. The jack contains a hand operated pump which draws oil from a reservoir .oil is pumped past a check or non-return valve into a linear actuator. The oil flowing into the actuator forces the piston back to the reservoir. Through the use of power driven pumps and directional control valves the simple systems have grown so that a number of loads can be handled independently or sequentially form the same power source. Power hydrualics is a power amplifier in which a small effort applied to a control device results in a large amount of work performed on a load. With boost servos ,hydraulic power aids the operator’s effort. Further refinement has led to the irreversible servo