Hydraulic motors are found in any app requiring rotational force, also known as torque. 
A hydraulic engine converts hydrostatic energy into mechanical energy by pressing vanes, gears or pistons attached to a crankshaft.
Hydraulic motors are utilized for many applications now such as for example 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 work in tandem with a hydraulic pump, which converts mechanical power into fluid, or hydraulic power. … Fixed-displacement motors drive lots at a continuous speed while a constant input flow is provided.