In terms of energy transfer: hydraulic technology is roughly in the middle of mechanical energy transfer and electrical energy transfer.

From the aspect of transmission characteristics: mechanical transmission and hydraulic transmission can be said to have fixed characteristics. In contrast, hydraulic transmission and electric transmission are the same, and have the characteristics of continuously variable transmission, in addition to constant power, It is easy to achieve characteristics such as constant speed and constant torque.

This feature of hydraulic technology can be summarized as follows:

(1) It is easy to carry out stepless speed change, and the shift range is wide, that is, the force and torque can be easily adjusted in a wide range;

(2) The control performance is good, that is, the force, speed, position, etc. can be correctly controlled with a high response speed. In addition, it has good adaptability to other control methods such as electrical and mechanical, especially in combination with electrical signal processing, and excellent response characteristics can be obtained;

(3) Reliable operation and good performance;

(4) Moderate flexibility in structure and characteristics;

(5) A circuit that can implement any complex function can be constructed with standard components.

The reason for these characteristics is that the volumetric components are used as the capacity converters, namely the hydraulic pump and the hydraulic actuator, and the lubricated oil (hydraulic oil) is used as the working medium. The general disadvantages of hydraulic technology are also related to hydraulic oil. These shortcomings are summarized as follows:

(1) Oil spill;

(2) When special precision control is required, the contamination of the hydraulic oil adversely affects the characteristics of the components and devices. That is to say, the management of hydraulic oil has a great influence on reliability and component life.