Air motors produce continuous rotary power from a compressed air system. Some of the big advantages over electric motors, which are to be mentioned:
- Air motors can be used in volatile atmospheres.
- Overload which exceeds the motor torque generally causes no harm to air motors. With electric motors, overloads can lead to overheating.
- Compressed air motors can reach high number of revolutions.
A big disadvantage is that air motors consume relatively expensive compressed air, so the cost of operating them might be probably greater than that of operating electric motors.
The applications are versatile. Above all, examples are to be mentioned here, in which explosion protection is necessary, for example chemical industry, painting plants and mining. Due to their small dimensions, they are suitable as a drilling unit, PU foam systems, mixing motors for spray heads, etc.
Controling pneumatic motors
Controling sense of rotation: If only one direction of rotation is used, a directional valve with 3 connections is used as control element. A reversal of rotation can be realized as illustrated with a directional valve, which has 5 connections (also used for double-acting cylinders).
Controling number of rotation: Generally, pneumatic motors are exhaust-throttled. Hereby you get a high tightening torque. Intake air throttling has the advantage that the air consumption is lower. However, the tightening torque is almost half as much as for exhaust air throttling.
Controling torque: Torque control takes place via a pressure control. Basically, the pressure regulator is installed in the supply line of the motor.
Types of pneumatic motors
The characteristic curve torque to rotational speed can be explained by the design. When the machine is at a standstill, the compressed air presses against the vanes with maximal pressure. As the speed increases, the vanes are pulled along by the compressed air. As a result, the pressure force and thus the torque of the motor decrease.