In a hollow-shaft motor the rotor is bored through. The motor mounts directly on the machine's shaft, held against rotation by a torque arm.
Why designers choose it
- No coupling and no alignment: the motor cannot be misaligned with a shaft it sits on
- A shorter, lighter drive with fewer parts
- Quicker installation and replacement
Where it fits
Conveyors, mixers and agitators, textile and process machinery: anywhere a shaft end is available and space is tight.
What to specify
- The driven shaft diameter and its tolerance, so the bore fit is right
- The keyway, or a shrink disc for a keyless, backlash-free connection
- The torque-arm position and the space around it
- Output, speed and duty, as for any motor
Fit matters: too loose and fretting wears the bore; too tight and the motor cannot be removed. We agree the fit with you on the drawing. See hollow-shaft motors.