Hi all,
this could be posted in 'running gear' section but is sod all to do with cars.
I understand how a diff works, but will a diff allow wheels to turn in opposite directions while under power?
Try again......
What I'm asking is, does a diff limit the turning circle of a vehicle to one wheel driven and the other static or wll it allow the vehicle to
turn around the center point of the rear axle.
Hope that makes sense.
Many thanks in advance
John
lost me
I underetand what you're asking, but wouldn't like to hazard a guess ! You must either have a long wheelbase or need a very tight turning
circle for this application..?
Ned.
come clean Spunky, what sort of idea have you got doing laps in your head? 
Some insane plan must have prompted this question
how do those little kybota mini diggers with 4 wheels with tyres on that scrub a lot work?
Ned.
They have slewing levers to brake each side independently while the other side still drives, usually by hydraulic wheel motors I think. Some reduction diffs as used on artic units may do what you are asking.
Almost 30 years ago my cousin had a tractor that had two levers; each one controlled the track on its respective side. You could spin it in its own
length.
But to answer your question I don't think its possible to do with a differential.
There is only one way to find out - build a really short wheel base car with a very tight turning circle. I think it maybe would turn both ways but am not sure. Need more thinking time.
Thanks fellas for those inconclusive replies
I've given it some more thought and still drawn a blank.
With one wheel locked the other will turn at double speed. If the turning radius was decreased further to less than than wheelbase then on wheel is
required to rotate 'backwards' I can see no reason why this would not simply increase the speed of the opposing wheel proportionately. But
doesn't sound right to have opposite wheel rotation.
Curious innit.
John
Something for robot wars?
quote:
Originally posted by Viper
Something for robot wars?
Spunky John -
That sounds right, because when you jack up the rear end of a RWD car with an open diff and spin the propshaft, each drive wheel turns in a different
direction.
That's how I test to see if a donor has a LSD - if it does, both drive wheels turn in the same direction under the circumstances above.
If the centre of rotation is in he middle of the back axle, there's no way you can make the turn happen under power from the prop, cos in this
case it's impossible to turn the prop! I dare say you can get quite close to it though.
You see what I mean - if the axis is in the middle the inner wheel will go EXACTLY as far backwards as the outer wheel goes forwards. Put another way,
to do it on a trike the front wheel would have to be exactly at 90degrees to the way the back axle's pointing - you ain't going nowhere!
cheers
Bob
ned, the kubota mini diggers with tyres on are actually small tractors fitted with backhoes and loaders. the reason they can turn so fast and tight is the front axle changes gear as you turn and the front end pulls you round.
it wont work, cos when the wheels are turning in opposite directions at the same speed, the prop isnt turning. If you turn it, you will move forward
or back. However, if you have the equivalent of a FWD bow thruster it would turn...
I think it would only work without power (ie. the wheels turning each other - no prop movement), but once the prop has power i reckon it wouldnt work.
Bear in mind this is based on a highly (in)conclusive test with a remote control car and could be wrong...........
quote:
Originally posted by JoelP
it wont work, cos when the wheels are turning in opposite directions at the same speed, the prop isnt turning. If you turn it, you will move forward or back. However, if you have the equivalent of a FWD bow thruster it would turn...
to spin around in circle you need two power sources, one wheel goes one way, the other goes the other. try driving a zero turn mower, they are great
fun