Worm Gear Gearbox

[Paul Copioli]

Back Drive-ability is a function of surface finish, lubricity, and worm lead angle. Using a bronze worm gear and a hardened steel worm (the small screw looking one), the max lead angle is 5 degrees to insure self locking. This is not a guarantee! What is a guarantee is that above 5 degrees, the worm gear set will not lock. The lead angle is the reason the window motor locks and the van door motor does not lock. It really has nothing to do with the gear ratio. A gear ratio of 50:1 with a lead angle of 15 degrees will not lock.

However, the more thread starts on the worm, the higher the lead angle and the lower the gear ratio is. Remember, gear ratio for a worm gear is # of teeth on the gear divided by number of thread starts on the worm.

-Paul

[greencactus3]

a little off, but for lego, wormgear 24:1 reductions work very well, for lego robots i mean. not too slow, yet (well since lego isnt efficient whatsoever,) efficient (make sure you wupport both axles from both directions, and since lego axles are plastic, support them as close to the gears as possible.
well, yea. worm gear gear boxes (wormgearboxes?) as an idea are very applicable ithink. except as with designing any kind of gearbox, will have difficult parts but if it works well, great!

...and yea, im understanding why my english teachers rarely give me any good grades on my essays.