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How to make a tricycle differential? Answered

How do you make a tricycle differential so that both wheels can be driven yet and rotate at different rates when going around a turn?  This would be for a human-powered tricycle.




1 year ago

2 freewheel sprockets welded at the tooth bit avoiding the actual teeth as a chain still needs to drive it., attach axles to the threaded section, thats as far as iv got so far

for a true differential,
Google "mower differential" and grab a transaxle from a ride on to get the gears
or "samagaga" makes a few if you want to buy or get plans

I've had simple plans for a freewheel diff on my site for a while....
http://www.packratworkshop.com/trike8.htm Simple design and easy to build.

Your drawing would be a lot easier to follow if you included an isometric view. I'm still trying to figure out how the spacer rings are fitted.

The inside of the rings are the same size as the outside diameter of the freewheel bodies. The rings are drilled so the bolts that clamp everything together fit between the teeth on the freewheels to lock the sprockets together with the larger driven sprocket used in the middle or put on either or both ends if you prefer.. Just remember to support the whole thing with bearings outside the differential on the axles.

o.k. here is how I did it- two bmx freewheels side by side in the center of the trike where the outer gears are welded together and driven by a gear sandwiched between them. the gears of the freewheels are therefore turned by the central gear but the axles are allowed to rotate independent of each other around turns. there is no limited slip though- if one wheel lifts that's the wheel that gets all the power just like an old car.

Hi, 2nup350!

Sounds great! and maybe gives me a solution to an off-roader
I'm thinking of building ..
Do you have a picture or sketch please


pics of an actual built unit. it is pretty clear how this unit works but fooling around with a pair of freewheels will make it even clearer.

Hi, 2nup350

I don't have access to any at present, so it's "diff"icult to imagine it in operation.
However, I imagine it cannot be described as a differential since it does not function in reverse and I need this for my quad bike design.

Thanks anyway,



this is the design i used

I've been wondering the same thing, and have been given similar "advice". I have a couple of approaches to this.

First is to look to the smaller (250cc) ATVs to salvage a rear-end from those. I'm pretty sure that there's going to be a little more parasitic drag, but it's going to be stronger than anything you can dish out to it with human power. The race ones will probably have lighter parts, I imagine. That goes for go-kart rear axles, mobility scooters, etc. I'm pretty sure any motorized vehicle that isn't considered a toy will have some sort of diff in the back (or front).

I've thought of another way as well which could be realllllly cheap. A regular bicycle rearend as the center of the axle, axle stubs out from either side, and a freehub (the ratchety part when you pedal backwards) on the ends of the axle, attached to each wheel hub. The differential action would take place at the wheel, not the center of the axle. It may only work with one side, as I do not know if freehubs are reversible.


7 years ago

This is a couple of photos I snapped of a home-built trike. Good luck!


when one wheel slips it will engage the other one.

make a limited slip differential

Drive both rear wheels thru a chain drive. Ratchet right and left so that if one goes faster than the other it will free wheel. For example, you maker a sharp right turn and the left wheel must move faster to keep up and not skid. So it freewheels and goes faster than the axle and does not skid.

... Yeah, that's probably simpler than a full differential.

Same way you do for any other power source; websearch "differential". Though for a human-powered vehicle, it would be simpler to let two wheels freewheel and power the third; that's how most tricycle-like vehicles work.