How to Select an Air Motor

Compressed air motors are advantageous in a variety of applications, including, but not limited to, the following:

• powering air driven machinery
• raising foundry copes and drags
• rotating a turntable
• mixing paint
• powering cranes
• steering fishing boats
• actuating valves
• powering mechanical hands

To assist in the selection of an air motor, you need to know any two of the following three items of information:

1. Horsepower required.
2. Speed (RPM) required against load.
3. Work load expressed in foot pounds or inch pounds of dynamic torque (i.e., moving torque load).

As air controlled motors are dependent upon input air pressure for performance, these factors must also be considered:

1. Air pressure (psig or bars) at motor location.
2. Pipe size of air supply system to assure adequate volume (cfm or cubic meter/min) so as to minimize line loss (air pressure drop during motor operation).
3. Plant air system pressure may vary during the day due to use by other equipment; therefore, base the selection of the air motor on the lowest psig or bars that can be expected.  Then, by using a pressure regulator in the line at the motor, a uniform air supply is assured.

Cooper Power Tools' pneumatic motors are engineered for great flexiblity, convenience, and reliability.  Cooper Power Tools combines three air motor product lines to give you a wide range of motor types and horsepower ratings.  The Dotco Air Motors and Buckeye Air Motors are rotary vane design.   Gardner Denver motors are rotary vane, axial piston and radial piston designs.   Pneumatic air motors provide a compact source of smooth, vibration-free power.  Cooper air motors cannot be harmed by overloading, unlimited reversing, or continuous stalling.  They are not affected by hot, corrosive, or wet environments, and they are explosion-proof and shock-proof.  Air motors start and stop instantly, while providing infinitely variable control of torque and speed.

Rotary Vane Air Motors are the most common air motors used in industry.  Compressed air enters the tool and is directed against vanes located in slots in the rotor, causing the rotor to spin.   A Cooper Power Tools air motor derives its power from the pressure of the compressed air.  Rotary vane motors are essentially high-speed motors delivering a high ratio of power-to-weight.  Some control over the power and RPM can be achieved by controlling the flow of air into the motor.  For a 10% change in air pressure, there is a 15% change in torque, from the RPM at maximum horsepower.   

If you require precise control of the torque and speed, consider the Gardner-Denver Axial Piston Motor.  Axial Piston Motors are relatively small in size, but they can develop high speed and high torque.    Axial piston motors have the advantage of having high torque immediately upon starting the motor.  The RPM and torque of the axial piston air motor can be controlled accurately by regulating the flow of air into the tool.

Radial Piston Air Motors are similar to a radial aircraft engine, except they are powered by compressed air.  Gardner-Denver Radial Piston Air Motors have 5 cylinders to give the motor maximum torque and smooth power.  Output torque is developed by air pressure on the piston within each cylinder.  A Radial Piston Motor can carry heavy loads at all speeds, and are particularly adaptable to operations requiring slow speed and high starting torque.

Cooper Power Tools manufactures the highest quality, industrial grade pneumatic air motor available.  Contact BlueTools.com to purchase a pneumatic rotary vane motor, axial piston air motor, or radial piston pneumatic motor for your particular work environment.