Worm Drive 5:1 Speed Reducer Backdrivin at 30 RPM

[randman2]

Can you back drive a worm gear 5:1 gear ratio, I would like to add a little drag to a cabled spooled down hill cart, the cable spooler has a 5 HP Euro drive with a 48:1 gearbox, the load with the brake off and no power to the motor will back drive the motor gear box ever so slowly, I would like to introduce a little drag assistance on the cart when going down hill to keep the load from creeping if the brake was to fail. The gearbox I would like to use is Hub City model 211A 5:1 bevel gear speed reducer rated at 240 inch pounds of torque, the gearbox will be back driven from the keyed shaft on the cart, the gear box will be back driven at 30 RPM. A little foot note when the spooler creeps (rotates) you can actually stop it by grabbing the flange of the spool. So introducing a little drag may solve the problem, if a 5:1 ratio is to steep maybe a 2:1.

 

[GregLocock]

Yes, it can be done. Designing the gearset is the tricky part. I suggest you ask the manufacturer whether that particular worm can be back driven. Luckily somebody has put the necessary formulae together here

http://www.roymech.co.uk/Useful_Tables/Drive/Worm_Gears.html

You want a design that doesn't self-lock.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[drawoh]

randman2,

Most worm gears self-lock at ratios of around 30:1. I think you can rig up a brake and accomplish the same thing at a much cost. Either way, you are converting kinetic energy to heat.

--
JHG