Two Engines Back Driving One Differential.

[Angel And The Wolf]

To fill this out a bit:
A reverse trike
Two CB750, or CB900 engines
Crankshafts connected 90 degrees out of phase,
RPMs always matched
8 separate firings every 2 revolutions.
Transmission outputs independently connected to opposite ends of differential
Transmissions shift-able independent of each other
Yoke of differential through shaft drive to rear wheel
10 useful up-shifts by shifting up one transmission at a time, then the other
Top 2 shifts employ putting one transmission in neutral, and braking that output
Engine in neutral turned off for top two gears

[cRiPpLe_rOoStEr]

Maybe some viscous-coupling would be the easiest approach.

[Angel And The Wolf]

A viscous coupling, in this case, would steal power.
Only the lower gear would be felt.
I've been looking at spur gear differentials.

[Angel And The Wolf]

On a spur gear differential, the input is usually to the ring carrier. In my application, the carrier would be the output, with a sprocket welded to it to run the chain to the rear wheel.

[Angel And The Wolf]

I guess I can't really hook two motorcycle engines solidly together, so let's kill the second engine.

ONE CB750, or CB900 engine

Two Transmissions (one with the engine, the second with the engine stripped away, and spun 180 around with it's output shaft opposite from the other.

Outputs independently connected to opposite half shaft ends of a spur gear differential

Transmissions shift-able independent of each other

Chain drive from ring gear carrier of differential to rear wheel

10 useful up-shifts by shifting up one transmission at a time, then the other

Top 2 shifts employ putting one transmission in neutral, and braking that output

[Isaac Zackary]

Here's a thought. If the engines must turn together or have one stopped, why not just have them connected together and disconnect them when you need to turn one off? Then have a single 10 or 12 speed transmission.

[Angel And The Wolf]

I don't really need two engines, and I can't think of an easy way to connect two motorcycle engines BEFORE the transmissions. I only need one engine, an extra transmission, and a Spur Gear Differential.

A CB900C HAS 10 speeds, but 5 of them are only 117% higher than the other 5, two are almost identical:

1st Low Range----- 13.99
1st (High Range)-- 11.97
(2nd) (Low Range)--9.54
2nd (High range)----8.16
(3rd) (Low Range)--7.45
3rd (High Range)---6.37
(4th) (Low Range)--6.14
4th (High Range)---5.25
(5th) (Low Range)--5.26
5th (High Range)---4.50

and many shifts require both an upshift AND a range shift. (Shifts are in Parenthesis)


Using two transmissions and a differential gives upshifts that require only one transmission upshift at a time, alternating left, and right. (Each shift is in parenthesis)

Shift
Patern
1/1 13.990
1/(2) 11.76
-------------------------------(Not Used) 1/3 10.720
-------------------------------(Not Used) 1/4 10.065
-------------------------------(Not Used) 1/5 9.625
(2)/2- 9.540
2/(3)- 8.495
--------------------------------(Not Used) 2/4 7.840
(3)/3 -7.450
--------------------------------(Not Used) 2/5 7.400
--------------------------------(Not Used) 1/neutral and braked 6.995
3/(4)- 6.795
--------------------------------(Not Used) 4/4 6.140
3/(5)- 6.355
(4)/5- 5.700
--------------------------------(Not Used) 5/5 5.260
--------------------------------(Not Used) 2/neutral and braked 4.770
--------------------------------(Not Used) 3/neutral and braked 3.725
4/(neutral and locked) 3.070
---------------------------------(Might have to machine another neutral stop
----------------------------------in second transmission shift drum past 5th.)
(5)/neutral and locked 2.630

You will notice that 4/locked, and 5/locked each give a higher cruising ratio than the CB900C's 5th High Range.

I chose these 10 ratios from the 20 possible for the ease of shifting.

Comparing the two patterns:

CB900C 10 speeds----------Two CB single range transmissions and differential

1st Low Range- 13.99------------------1/1 13.990
1st High Range 11.97-------------------1/2 11.765
2nd Low Range---9.54------------------2/2 9.540
2nd High range---8.16------------------2/3 8.495
3rd Low Range----7.45------------------3/3 7.450
-------------------------------------------3/4 6.795
3rd High Range---6.37------------------3/5 6.355
4th Low Range----6.14
-------------------------------------------4/5 5.700
4th High Range---5.25
5th Low Range----5.26
5th High Range---4.50
-------------------------------------------4/neutral and braked 3.070
-------------------------------------------5/neutral and braked 2.630

[Angel And The Wolf]

I am abandoning this thread. I've just done a top speed in steps study, and the first 8 steps are extremely close ratio steps.

1/1 47 MPH
1/2 56 MPH
2/2 69 MPH
2/3 77 MPH
3/3 88 MPH
3/4 96 MPH
3/5 103 MPH
4/5 115 MPH
4/N 214 MPH
5/N 250 MPH

Not very useful on a street trike.

I thank those who had suggestions.

[Isaac Zackary]

It was fun brainstorming. I too have often thought of ways to design my own lots-of-speeds transmissions. Now I'm driving a CVT Hybrid and loving it.

[Frank Lee]

I don't get it, but then I'm a flatlander. I want three gears, top "gear" being direct drive: no power flowing through gearsets. And I don't want to spend a lot of time shifting. Hell, even with 5-speed trannys I skip shift.