CVT diferential

Discussion in 'Motorized Trikes' started by jawnn, Jul 6, 2009.

  1. jawnn

    jawnn Member

    Is it possible to use a motor with a threw axle (a cvt on both sides to the two rear axles) as a differential? (is that even possible?)

    Some how I just can't see the inside cvt sliping enough.

    So what would happen if it didn't?

  2. loquin

    loquin Active Member

    If it was a Nuvinci, then, I don't see how they could slip by itself.

    If it was a belt-drive, then, it should be able to slip enough.

    However, if the CVTs connect to the rear wheels using a freewheel sprocket, though, they could slip as needed. The outer wheel would be driving the bike, the inner wheel would rachet the freewheel a few times as the bike corners.

    The only issue I would have with two belt-type CVT's would be driving two separate sources of power loss... (85-90% each, means a system with 72-81% efficiency.)
  3. loquin

    loquin Active Member

    How does the bike work now?
  4. jawnn

    jawnn Member


    for some reason I just can not see that it will rachet if wheel only rachets when turning and the drive does not.

    now the trike has only one drive wheel.
  5. jawnn

    jawnn Member


    I did some visualizing last night and decided that If the wheel to the inside of a turn is moving slower, the outside wheel will be the one to ratchet.

    This also means that I have to use a free wheel on the motor shaft to make it possible to turn left with pedals only. Right? Maybe not? this is a single wheel drive trike (on the right side)

    If I use 18 sprockets on the motor shaft and 34 on the axles will the motor turn fast enough not to stall out on the steep hills (400lbs at 12 degrees) with pedaling???

    I don't mind sacrificing speed if I can get by with out the cvt's speed is not my goal in life.

    And I wouldn't mind a little less efficiency if I can have more traction on the hills.

    What is the smallest motor that will work??? Is there one that w/ axles sticking out on both sides??

    And what is the smallest amount of sprockets that will fit on a single speed free wheel?
    Last edited by a moderator: Dec 15, 2015
  6. Jax Rhapsody

    Jax Rhapsody Member

    Most trikes(exc mine) drive a single wheel. which sucks but I know I havent posted in a while and I'm not trying to spam but I've been trying to find the make and yesr of my trike and ran across and they make a positraction kit. It's for converting tadpoles into quads but it could be adapted to a regular trike. You can also use mid drive hubs, which would require dual chains but it'd be worth it.
  7. jawnn

    jawnn Member

    stalling on hills?

    Did I stump the experts on this thread?

    I really need to know how small an engine I can use with out stalling on the hills with using pedal power as well. How slow can these engines run and still deliver power?
    Last edited: Jul 14, 2009
  8. SimpleSimon

    SimpleSimon Active Member

    A differential for a delta trike is pretty straightfoeard to fab up. As pictured, it requires 4 sprockets of identical tooth counts - the blue translucencies represent the plane of the chain loops. I am putting the pictured assembly into my trike conversion - two spockets mounted to the spoke flanges of a Shimano 3 speed internally geared hub, with seperate half-axles to each rear wheel with freewheels mounts on the sprockets on the internal axle ends. As drawn, I show a jackshaft that allows for power output from an HT engine to be carried over to the right side, a freewheel equipped (so the engine doesn't drive the pedals) sprocket from the pedal chainring on that jackshaft, and the combined drive sprocket to the Shimano hub.

    Attached Files:

    Last edited: Jul 14, 2009
  9. loquin

    loquin Active Member

    No, but, we've answered this question before, several times. It depends upon the gearing and top speed.

    A 25cc engine would work fine if you only want to cruise at 4 or 5 mph top speed with fixed gearing.
  10. duivendyk

    duivendyk Guest

    1) The outer wheel,not the inner one ratchets with freewheels
    2) A single CVT cannot play diff. no matter what it is
    3) Dual belt type CVT's would seem problematic if they were speed controlled,if torque&speed controlled it should be a different matter,I think the argument that the overall efficiency is the product of the individual ones is incorrect (each 0.9 would get you 0.81 overall).It would be somewhat lower but not much,but unless they were identical, one would be doing the heavy lifting unless they were torque sensitive,It's a can of worms,stick with freewheels.
    4) I assume your engine has an internal reduction.Assuming 20" wheels the speed is
    S=0.058x rpm/R in mph,R is total reduction from crankshaft ,with an internal reduction of 5? , R becomes 5x38/18= 10.55 and at 5000rpm we get S=27.5 mph,assuming a max torque of 2.5 Nm
    (1.8 ft.lbs ).The torque at the wheels would be 1.8x10.55 xeff (0.85?) =16ft.lbs, or 20lbs tractive force.An angle of 12 degrees is extremely steep,corresponds to a 21% grade.You must have got your numbers wrong.Assuming 450lbs total weight,you could climb a 20/450=0.044 grade or 2.5degrees,With a CVT and max ratio of 3 say (3-1.5) reduction you could do 7.6 degrees.Your speed at 5000rpm would be 27.5/1.5=18.3 mph.
    All this is predicated of course on the 1.8 ft.lbs torque assumption (1.74 HP at 5000 rpm)
    Last edited by a moderator: Jul 15, 2009
  11. jawnn

    jawnn Member

    another brain storm

    another brain storm gave me this answer:

    The answer to this wild idea is to connect the pedals and the motor to a jack axle, then forget about the quarter hp I do with my legs because most of it wil be wasted by the friction belts of the cvt's.

    So is there an automatic gear system that does not use V belts? And an affordable price? Dream on.
    Last edited by a moderator: Dec 15, 2015
  12. jawnn

    jawnn Member

    hub motor

    I realy like the geared hub idea but I think that a 48 voolt geared hub motor will work the best.....mounted behind the seat, and chained to the axils.