All three types of power (mechanical, electrical and hydraulic) are typically involved in hydraulic systems, as illustrated in Figure 3-25. In this diagram an electric motor is as the prime mover to drive the pump. As shown, the electric motor converts electric power into mechanical power via a rotating shaft. The pump converts this mechanical power into hydraulic power. Finally, hydraulic cylinder or hydraulic motor transforms the hydraulic power back into mechanical power to drive the load. A hydraulic cylinder delivers a force to move the load in a straight-line path with a linear velocity .Conversely a hydraulic motor delivers a torque to move the load in a rotary motion with an angular velocity.