TORQUE ARMs and HOLLOW SHAFT GEARBOXES

[fundiz]

I've been told that a torque arm is used on a hallow shaft gearbox in order to prevent the gearbox from wanting to rotate along with a shaft. I don't understand how this can happen if the gearbox is face mounted on a conveyor (the mounting bolts should prevent rotation).
I've also been told a torque arm is strongly recommended on any hollow shaft gearbox. Can anyone explain why?

 

[tygerdawg]

Torque arms are used when the gearmotor is NOT bolted on the face, but are solidly clamped on the conveyor shaft. If face-bolted, then torque arms aren't needed.

TygerDawg

 

[fundiz]

Any other instances in which you would want to use a torque arm?

 

[arto]

where you don't want to transmit loads/heat etc into the gearbox wall (i.e., thermal expansion) like on a pressure vessel.

 

[MikeHalloran]

Also, if you're driving something that jams occasionally, you can preload springs against the torque arm, and install switches to detect a jam and turn off the motor.



Mike Halloran
Pembroke Pines, FL, USA

 

[PersonalProfile]

I suspect the situation you are referring to is when the drive is supported at the pulley (by the output shaft via rigid coupling) and at the torque reaction arm (only - no other support). This is a common arrangement for "larger" drives. When the torque reaction opposes the drive mass it can sometimes result in the torque reaction arm requiring tension capacity, though typically there torque reaction arm is in compression (due to the drive mass).
If the drive was face mounted to the conveyor, I would assume that the face mount would transmit all of the loads and not other restraint (i.e. torque arm) would be required.
Torque reaction arms can lend themselves for monitoring as mentioned.
Regards,
Lyle