Hydraulic motors are found in any application requiring rotational force, also known as torque. A hydraulic motor converts hydrostatic energy into mechanical energy by pushing vanes, gears or pistons mounted on a crankshaft.
Hydraulic motors are utilized for many applications now such as winches and crane drives, wheel motors for military vehicles, self-driven cranes, excavators, conveyor and feeder drives, cooling fan drives, mixer and agitator drives, roll mills, drum drives for digesters, trommels and kilns, shredders, drilling 
rigs, trench
Hydraulic motors are rotary actuators that convert hydraulic, or fluid energy into mechanical power. They function in tandem with a hydraulic pump, which converts mechanical power into fluid, or hydraulic power. ... Fixed-displacement motors drive a load at a constant speed while a continuous input flow is provided.