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worm gears in powertrain of baja buggy

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deepak123shukla View Drop Down
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    Posted: Jun/07/2015 at 12:16pm
I was wondering that why cannot we use worm gears in powertrain of a baja buggy.for it can give us large reduction along with reducing overall weight of the assembly. though I have searched abt the worm gears used in automobile;it was in 1960s , so can we retrieve that technology.
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Pedro UFPBaja View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Pedro UFPBaja Quote  Post ReplyReply Direct Link To This Post Posted: Jun/07/2015 at 4:18pm
Unlike with others types of gear sets, when using worm gear the direction of transmission (input shaft vs output shaft) is not reversible. Will be needed a ratchet or the wheels will lock when the driver stop pushing the throttle. So your system will be unable to perform engine-brake to reduce the speed on deceleration. 
With a ratchet will be a huge gap on the acceleration curve because the engine and the transmission will first synchronizing again before perform the increase of rpm. Possibly locking the wheels at some time on tre process.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Nate Quote  Post ReplyReply Direct Link To This Post Posted: Jun/07/2015 at 5:38pm
You could say that's an advantage having the ability to engine brake... all depends on how you want your car to handle.

http://www.machinerylubrication.com/Read/1080/worm-gears

Sounds like lubrication is the reason to not use it. You'll also only have a forward gear, and like pedro said, ratcheting or spraging is the only way to move the car forward when the engine is slowed or stopped.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote deepak123shukla Quote  Post ReplyReply Direct Link To This Post Posted: Jun/08/2015 at 6:29am
I thought it may be the lead angle which is the limiting factor by which we can say if the gears will rotate the worm or not.
so if that satisfies I think there is no harm in using.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote collinskl1 Quote  Post ReplyReply Direct Link To This Post Posted: Jun/08/2015 at 6:58am
Worm gears are certainly able to be backdriven. Deepak is on the right train of thought with the point about the lead angle... certain leads generate a geometry that can't be backdriven.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Pedro UFPBaja Quote  Post ReplyReply Direct Link To This Post Posted: Jun/08/2015 at 9:31am
Well, even with lead angle that allows reverse direction, it's not an efficient configuration, too much friction.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote collinskl1 Quote  Post ReplyReply Direct Link To This Post Posted: Jun/08/2015 at 10:08am
There is certainly an efficiency hit compared to spur gears, but depending on your design space it may be acceptable.
Kyle Collins
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