Air Motors Information

Air motors are powered by compressed air. They operate at relatively high speeds in industrial and spark-prohibited applications. They can be regulated easily for speed and torque, and can stop and reverse very quickly. They are commonly used in many industrial applications and are noted for their economic power delivery, straightforward maintenance and safety in spark-prohibited applications.

Performance Specifications

The most important performance specifications to consider when searching for air motors include required torque, maximum air pressure, air consumption, rated free speed (output), and operating noise level.  Torque is the turning force delivered by a motor or gearmotor shaft, usually expressed in lbs. ft derived by completing H.P. x 5250/RPM = full load torque.  The maximum air pressure is usually specified in pounds per square inch.  The air consumption of the motor can be specified by minimum, maximum, or both.  The rated free speed is the speed with no load at rated pressure. Note that this is the speed of the output shaft for a gearmotor.  The operating noise level is the noise level in decibels (dB) produced by the motor.

Output Styles

Output styles for air motors can be output shaft of hollow shaft or collet.  With a shaft the output is solid shaft, typically cylindrical.  A hollow shaft or collet is an output shaft with a center hole for tool mounting, or a collet style for adjustable tool clamping.  The diameter of the shaft or collet is also important to consider.

Gearmotor Specifications

Gearmotor specifications that are important to consider when searching for air motors include whether or not the air motor is a gearmotor, the gear reduction ratio, and gearmotor output style.  A gear motor has an integrally attached gearhead, usually for the purpose of reducing speed and increasing output torque.  A 10:1 reduction ratio would be represented by 10, a 3:2 ratio represented by 1.5, etc.  Gearmotor output styles include concentric or in-line output, parallel or offset output, and right-angle output.

Mounting Options

Mounting options for air motors include face mount, flange mount, nose mount, and foot mount.  Common materials of construction include aluminum, cast iron, steel, stainless steel, and plastic.  Features commonly found on air motors are non-lubricated construction, reversible, and speed feedback or control.  Dimensions of length, side or diameter, and weight are also important to consider.


Air motors are sometimes used to start engines or turbines, in which case they are referred to as air starters.


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