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Old 04-03-05, 07:02 AM   #1
savarin
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differential wanted

Does anyone know of a source for a lightweight rear differential? I want to use it on a recumbent trike I'm designing.
An australian source would be even better.
Thanks.
Charles
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Old 04-04-05, 09:43 AM   #2
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interesting question. I don't know of one, but on the trike we pulled out of a dumpster the rear drive is to a solid axle. Now that I think about it, I'm not sure if its fixed drive to one wheel & the other can 'overspeed' or if both wheels are on freewheels so you're always driving the inner wheel. The point: there's more than one way to skin a cat; you might be able to use typical bike parts rather than adapting a differential. Though if you do use a diff, I'm interested in seing your results!
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Old 04-04-05, 11:44 AM   #3
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Old 04-04-05, 12:49 PM   #4
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I'll sell you the spare differential for my mercedes turbo-diesel. I think it only weighs about 85 pounds with fluid, is that OK?

Seriously though, while I think there are some lightweight differentials, it might make more sense to go with a freewheel sort of situation where only the slower wheel is driven at any time, and the outer wheel can 'coast' at a higher speed. This would have the opposite effect of a normal differential, the slower wheel would get the torque, and the faster wheel wouldn't. Normal differentials send all the power to the fastest wheel, which might be a problem if you were skidding or sliding at all.

peace,
sam

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Old 04-04-05, 03:01 PM   #5
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Normal differentials give equal torque to both wheels, which results in more power to the outside wheel.
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Old 04-04-05, 03:13 PM   #6
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Quote:
Originally Posted by AndrewP
Normal differentials give equal torque to both wheels, which results in more power to the outside wheel.
Yup, equal torque, unequal power. Thats good normally, but bad when one wheel starts to slip! I don't think they make limited slip differentials for bikes, but a double-freewheel situation would work similarly, the slowest wheel (and hence the one with the most traction) would get the torque.

peace,
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Old 04-04-05, 06:17 PM   #7
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That freewheel is so clever! Great Idea!
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Old 04-04-05, 08:45 PM   #8
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Quote:
Originally Posted by halfbiked
interesting question. I don't know of one, but on the trike we pulled out of a dumpster the rear drive is to a solid axle. Now that I think about it, I'm not sure if its fixed drive to one wheel & the other can 'overspeed' or if both wheels are on freewheels so you're always driving the inner wheel. The point: there's more than one way to skin a cat; you might be able to use typical bike parts rather than adapting a differential. Though if you do use a diff, I'm interested in seing your results!
All the rear ends I've seen to date (not many unfortunately) only drive one wheel.
I want to drive both wheels but still get the differential speed difference when turning.
Yes, I know that if one wheel slips it will get all the power but where I ride that would hardly ever occur so I do not believe it would be a problem. (Rain! what rain?) Mind you, its often better to check reality and prove it rather than let mind problems stop the trial.
I have designed a simple diff that could be bolted together from ally stock and mitre gears if I cannot find what I want.
Regards
Charles
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