Two Engines Back Driving One Differential.

[Angel And The Wolf]

If I connected the drive shafts of one engine and five speed transmission to the left half-axle of a differential, and a second engine and five speed transmission to the right-half axle of the same differential, how many different ratios can I get at the center drive of the differential, and how would I calculate each?

I would include 1L/1R, !L/2R, 1L/3R, 1L/4R, 1L,5R, 2L/3R, 2L/4R, 2L/5R, 3L/4R, 3L/5R, 4L/5R, and 1L, 2L, 3L, 4L, and 5L, with the Right engine cut off.

I count 16 distinct gear ratios,(more, if I include independent throttle pedals) but I just don't know how to calculate backwards through a differential.

[Ecky]

If I'm understanding right, you can have nearly infinite ratios, because of how a differential works. Varying the RPM of the two engines will affect the speed of the center drive too. I think?

[Angel And The Wolf]

Yeah, I think so, too, that is, IF, a differential can be driven backwards.

[cRiPpLe_rOoStEr]

Originally Posted by Angel And The Wolf

If I connected the drive shafts of one engine and five speed transmission to the left half-axle of a differential, and a second engine and five speed transmission to the right-half axle of the same differential, how many different ratios can I get at the center drive of the differential, and how would I calculate each?

Sounds like the differential would become pointless in this case. If you'd want to couple two engines to a same final drive, it might be easier to consider the example of that GM Scenicruiser bus. Or something analogue to the power-split device fitted to the Prius.

[Angel And The Wolf]

It's probably more of an excess than useless. Who really needs a 16 speed tranny, or two engines? Just a mind exercise. If you remember my thinking on two CB900C engines, and how they might overpower a single CB900 transmission, this would allow a transmission for each. They could be shifted together, but if one was mis shifted, the Differential would protect from over- or under- revving the other.

[Frank Lee]

Use the road as your limited-slip differential- each drivetrain gets it's own wheel.

[Angel And The Wolf]

Frank, if I shift one engine, and mis-shift the other, it will be like putting the brake on the mis-shifted side.

[Frank Lee]

Use one shift linkage for both.

[cRiPpLe_rOoStEr]

Maybe something similar to the clutch system used in those tiller-tractors still widely popular in Southeast Asia (one per wheel) which is able to compensate the lack of a differential while cornering on pavement is more likely to perform the way you want.

[seifrob]

Or like ZIL 135, one engine transmission combo for each side, no interconnection between wheels, but road.