Hydraulic machinery uses the principle of fluid mechanics to increase the mechanical strength of the equipment and tools, which can be applied to hydraulic pliers, hand-pushed hydraulic forklifts, and other small tools. It can also be applied to some heavy equipment. In heavy equipment, for example, hydraulic fluid is delivered at high pressure to the actuator in the equipment through a hydraulic pump. The hydraulic pump is driven by an engine or an electric motor. Control the hydraulic oil by manipulating various hydraulic control valves to obtain the required pressure or flow rate. The hydraulic components are connected through hydraulic pipes. Like the pneumatic system, the hydraulic system is based on PASCAL's law; Any fluid pressure applied to a closed system at any point will be transmitted to all parties with the same pressure. Hydraulic systems use incompressible fluid (rather than compressible gas) as the working medium.
Hydraulic mechanical equipment is widely used because the transmission power is large, and the transmission of fine pipes and flexible hoses, so its power density is high, and the applicable power actuator is broad and flexible, and the pressure area is appropriately changed to increase the force. Compared with the mechanical system composed of gears and shafts, one disadvantage of the hydraulic system is that the fluid resistance flowing through the pipeline will cause a certain power loss.
Hydraulic systems are characterized by the ability to double forces and torques in a simple manner, independent of the distance between inputs and outputs, without the need for mechanical gears and levers to be connected, either by changing the effective area of either of the two connected cylinders, or by changing the actual displacement (ml/r) of either of the pumps and motors. When designing machinery, hydraulic ratios are often considered in conjunction with other mechanical ratios of force or moment to achieve optimal performance.
