Industrial hydraulic motor
A hydraulic motor works by taking pressure from a liquid, most often an oil, and turning it into mechanical torque. Hydraulic motors can be very powerful, though they have high maintenance requirements because of their need for constant pressure.
Mechanics
A hydraulic motor does not work by itself; it must exist within a closed loop system. Necessary components include a pump to supply pressure, a reservoir of fluid -- with oil being the most common -- and tubing to connect all the systems. Multiple motors can be attached to this system, but without the addition of pumps their use will result in a parasitic pressure loss to the entire closed loop system. Within the motor the pressure of the fluid turns a turbine that is attached either directly to the axle in smaller applications, or to a transmission in larger applications, to control the torque and speed.
Common Uses
Hydraulic motors are used in everything from adjustable car suspensions and construction machines to animatronics and elevators. The uses are endless, though the most common are in industrial applications. They are often found in excavators and the doors to industrial grade kilns.
Formula
Hydraulic (fluid power) horsepower can be calculated as follows: HP = PSI x GPM ÷ 1714. PSI is gauge pressure in pounds per square inch, and GPM is oil flow in gallons per minute.
Of special note: To idle the pump in a hydraulic system you need 5 percent of the rated power and even more if the system is operating at less than peak efficiency.
