Torque to Back drive a worm and wheel gearbox.
Torque to Back drive a worm and wheel gearbox.
(OP)
Hi All
I am having difficulty in determining the torque required to back drive a worm and wheel gearbox. I have calculated the efficiency of the gearbox when the worm is driving and when the wheel is driving.
I understand that when the efficiency of the wheel driving is less than zero the gearbox will not backdrive, however there must be an input torque at which you can force the wheel to turn the worm.
Does anyone know how to calculate this? Any help would be appreciated.
I am having difficulty in determining the torque required to back drive a worm and wheel gearbox. I have calculated the efficiency of the gearbox when the worm is driving and when the wheel is driving.
I understand that when the efficiency of the wheel driving is less than zero the gearbox will not backdrive, however there must be an input torque at which you can force the wheel to turn the worm.
Does anyone know how to calculate this? Any help would be appreciated.





RE: Torque to Back drive a worm and wheel gearbox.
What are the particular conditions that would need the back drive capability?
- - -Dennyd, P.E.
RE: Torque to Back drive a worm and wheel gearbox.
RE: Torque to Back drive a worm and wheel gearbox.
Is the drive motor electric or hydraulic? If it is hydraulic you can close the inlet and exhaust ports with a valve and that may provide adequate braking. If the motor is DC electric you may be able to switch its terminals to where they are shorted, which does a surprisingly good job of braking. If the motor is AC electric you might have some other electronic braking options, but I'm not knowledgeable enough about electric motors for that.
As I proof this and reread your comments it sounds more like your problem is one of output positional creep and not one of backdriving torque. Is that correct?
- - -DennyD, P.E.
RE: Torque to Back drive a worm and wheel gearbox.
In order to be able to help you in your quest for an answer it would be best to submit information on the drive:
What type of motor are you using AC, DC, Pneumatic or Hydraulic?
What is the power and speed of the motor?
How is the motor controlled?
Is the motor directly coupled or via another drive system ie belt & pulley, chain & sprocket, if so what is it?
What size is the worm gear reducer? Metric or Imperial?
What is the load?
What is the operating cycle?
What is the mounting position?
What is the application?
With this information I may be able to assist you.
Regards
simongee
RE: Torque to Back drive a worm and wheel gearbox.
The system is driven by a DC motor, with max power of 1kW @ 4800RPM. It is controlled through simple control gear, but the motor does get shorted out when stationary. The motor and Gearbox are coupled to the driven device through a sprocket & chain. The ratio is 60:1 (metric), which is holding a load on a slope equal to 25Nm. But we are finding that the load still moves, backdriving the gearbox. Although I can not reproduce this on the bench, by enducing a similar torque into the gearbox.
RE: Torque to Back drive a worm and wheel gearbox.
RE: Torque to Back drive a worm and wheel gearbox.
Thanks Again
Matt
RE: Torque to Back drive a worm and wheel gearbox.
Can you change to a different or eliminate the lubricant? If this is an intermittent use or few total hours expected life it may be possible to run without lubricant.
I'm not saying this is a good idea, just something to consider.