The two ports may be alternately used as inlet and outlet, thus providing rotation in either direction. Note the springs in the slots of the rotor. Their purpose is to hold the vanes against the housing during the initial Figure 10-13. Vane-type air motor. The most commonly used hydraulic motor is the fixed-displacement piston type.
Some equipment uses a variable-displacement piston motor where very wide speed ranges are desired.
This pump-motor combination is used to provide a transfer of power between a driving element and a driven element. Some applications for which hydraulic transmissions may be used are speed reducers, variable speed drives, constant speed or constant torque drives, and torque converters. Rapid, smooth acceleration or deceleration. Control over maximum torque and power. Cushioning effect to reduce shock loads.