Diagram of a simple hydraulic pump-motor system
1 Reservoir, 2 hydraulic pump, 3 pressure gauge, 4 hydraulic motor (suitable for left and right hand rotation)
In fact every hydraulic system can be reduced to a simple pump-motor system as shown in the diagram
The hydraulic pump is driven bij an electic motor or a combustion engine. The hydraulic pump (2) sucks oil from the reservoir (1) and pumps the oil through the pipelines and hoses to the hydraulic motor (4). The hydraulic motor for example drives a winch. So the hydraulic pump converts mechanical energy into hydraulic energy (pressure and flow) and the hydraulic motor converts the hydraulic energy into mechanical energy again! From the exhaust side of the hydraulic motor the oil flows back to the reservoir. In the returnline the pressure is almost zero! The pressure needed to drive the hydraulic motor can be read on the pressure gauge (3), and is determined by the resistence in the system. The most important resistance is the load to be driven by the hydraulic motor (4)! Lines and hoses also have a certain influence on the level of pressure.
The speed of the hyraulic motor is determined by it's dimension (displacement) and by the flow that is pumpt into it.