LSD Differential

[silente]

Hi Everybody.

I am currently working on a formula car using a Hewland Gearbox + power flow differential.

The differential is a ZF type with friction plates and ramps.

Reading the manual i learnt that this kind of differential (which is torque sensitive) has a costant value of "Locking effect" depending on plates and ramp configuration.

On the other side they said that, if you have a given Preload, then differential is locked till the difference in torque is higher than the preload.

What does it mean exaclty? that if:

(Torque slow wheel - Torque fast wheel) < Preload Torque

Than the diff is working like a rigid connections between the two wheels? so that the wheel are sharing the same torque and the same speed?

Does anybody has any experience with this kind of differentials?

Thanks!

[tristancliffe]

Yes, if the torque difference wants to be less than the preload torque the diff behaves as a locked diff. Above that torque it behaves with a limited slip action that depends on the clutch configuration (how many friction surfaces are in use) and the ramp angles on power and coast sides.

Without preload you'd find that at times the diff became completely open, which is usually a bad thing for handling balance. A figure of 10-20 lb-ft is usually a perfectly good starting point, and in many cases you'll never change from that (other than shimming for wear to regain the initial torque).

There are sites and discussions about clutch pack differentials around. I'll try and dig up some of the better ones.

[silente]

thanks a lot Tristan, if you can send the links i would be happy to take a look at them!

I have to model the Diff in a simulation of the whole car and i wasn't able to figure out some things. I try to adjust them and see but maybe i am going to ask again!