Reverse differential operation

[sankar8381]

if input is given to wheels and output taken at the shaft coming to the differential. if w1 is the angular velocity of wheel 1 and w2 the angular velocity of wheel 2 .what is the angular velocity of the transmission shaft?

[MagicRat]

((W1 x W2) / 2) x (gear ratio) = driveshaft speed

EDIT: this formula should be

((W1 + W2) / 2) x (gear ratio) = driveshaft speed

[Black Lotus]

Assuming the diff is OPEN, and both wheels are off the ground--
and if the driveshaft has any resistance applied to it (i.e. in gear) the speed of W1 and W2 will be the same, but rotate in opposite directions.
If the driver applies power, and if one wheel on an open diff has traction, and the other wheel has no traction, (or not enough) the wheel with no traction will spin at ABOUT twice the speed that it should.

If it is a limited slip type, like I thing Mr. Rat is talking about, he is correct as well.

I have a Quaife type diff. in one of my cars, and I'm not sure at all what happens there. Only that it almost works well.

[MagicRat]

Originally Posted by Black Lotus

Assuming the diff is OPEN, and both wheels are off the ground--
and if the driveshaft has any resistance applied to it (i.e. in gear) the speed of W1 and W2 will be the same, but rotate in opposite directions.
If the driver applies power, and if one wheel on an open diff has traction, and the other wheel has no traction, (or not enough) the wheel with no traction will spin at ABOUT twice the speed that it should.

If it is a limited slip type, like I thing Mr. Rat is talking about, he is correct as well.

I have a Quaife type diff. in one of my cars, and I'm not sure at all what happens there. Only that it almost works well.

My little formula is simply a mathematical representation of differential operation and thus the type of diff (open or LSD) is not relevant.

. As you suggest some caveats are required for practical application For example, if the wheels are traveling in opposite directions, the velocity of one wheel must be represented as a negative value.

[Black Lotus]

Originally Posted by MagicRat

. As you suggest some caveats are required for practical application For example, if the wheels are traveling in opposite directions, the velocity of one wheel must be represented as a negative value.

So which is positive -- the wheel that is turning clockwise or counter clockwise?

[sankar8381]

Originally Posted by MagicRat

((W1 x W2) / 2) x (gear ratio) = driveshaft speed

suppose you want to add up the the power produced by 2 shafts which are rotating at different rpms.and transmit the power to the third shaft ,How can we implement this? are u sure your formula is correct.if w1 =100,w2=100;according to you the shaft rpm is gonna be 5000.

[MagicRat]

Originally Posted by sankar8381

suppose you want to add up the the power produced by 2 shafts which are rotating at different rpms.and transmit the power to the third shaft ,How can we implement this? are u sure your formula is correct.if w1 =100,w2=100;according to you the shaft rpm is gonna be 5000.

Whoops, the formula should be:

((W1 + W2) / 2) x (gear ratio) = driveshaft speed