Thread: What is an Air Locker??

Originally Posted by miky

Not too sure that a locker is necessarily "better" than traction control in loose sand. If you watch the videos (elsewhere on this site) of the Defender with TC/ABS you can see the TC cutting in and out preventing wheel spin, but the Defender is still going forward as if nothing is going to stop it.

The advantage of the locker in sand is that the brakes are not applied which slows it down and traction is spread evenly to the wheels. The wheelspin which ETC allows also creates a degree of dig, something that may not be significant with HT tyres, but can be with bog type tyres. As the ETC brakes the spining wheel it can then start to shunt wheelspin around to the other wheels.

This said, I think that ETC is a lot better than nothing and there isn't a lot between it and lockers in sand - but by far the biggest influence with sand driving is tyre pressures and then tread pattern. If you get these right, then the ETC barely triggers anyway.

Originally Posted by miky

Not too sure that a locker is necessarily "better" than traction control in loose sand. If you watch the videos (elsewhere on this site) of the Defender with TC/ABS you can see the TC cutting in and out preventing wheel spin, but the Defender is still going forward as if nothing is going to stop it.

on trip that i have been on the guys with traction control seem to use more revs than guys with lockers.....keep in mind that i have never driven a rig with traction control but the way i see it is you have to get wheel spin before it cuts in

plenty of guys fit lockers to the traction controlled rigs

Originally Posted by Slunnie

This said, I think that ETC is a lot better than nothing and there isn't a lot between it and lockers in sand - but by far the biggest influence with sand driving is tyre pressures and then tread pattern. If you get these right, then the ETC barely triggers anyway.

Yeah I agree. My trips to Stockton hardly ever saw TC come on. Then again, maybe I need to push harder

It can be quite hard to visualise all of the components working together - Traction control, LSD and/or lockers and CDL....

I'm probably a bit late in this thread, but this question came up on the Stage1 forum and this is how I explained it. The drawings might help anyone if they are still confused and it might be useful reference in future perhaps? Righto here it is... pasted...:

Say you are stuck, and all each of your tyres has various levels of traction. In this case the tyre with the least traction is shown as number 1 (say it is off the ground), the one with the highest traction is shown as number 4 (say it is solidly placed on a rock) and 2 & 3 are somewhere between these two extremes.

If you were in this situation with your central diff unlocked this is where your power would go:



Straight to the tyre that is in the air (number 1) all the other tyres will have no drive at all. You won't be going anywhere here.

If you were in the same situation again and you engaged your center diff lock this is where your power would go:



Since tyre number 1 is in the air it does nothing for you here, but now power is being delivered to the rear to tyre number 2 which is probably on the ground but if it doesn't have enough traction to push or pull you out it will just spin at the same rate as number 1. Tyres 3 & 4 which have more traction but no power will be delivered to them.

Say you have installed a lockable differetial to your front diff. It's quite a different story:



You now have positive drive on tyres 1 (essentially useless), 2 & 4, this will probably get you out... since we have said that number 4 is on a nice solid rock and it now has drive... but if you are badly stuck this may not provide enough traction.

If you have really gone nuts and fitted two lockers to your car this would be the story:



All tyres will have drive, and in this configuration you have A LOT of traction, you would have tyres 1 (spinning uselessly), 2, 3 & 4 pulling. If this doesn't get you out... you better hope you have a winch or a few cars to pull you...

Originally Posted by stirlsilver

If you were in the same situation again and you engaged your center diff lock this is where your power would go:



Since tyre number 1 is in the air it does nothing for you here, but now power is being delivered to the rear to tyre number 2 which is probably on the ground but if it doesn't have enough traction to push or pull you out it will just spin at the same rate as number 1. Tyres 3 & 4 which have more traction but no power will be delivered to them.

Say you have installed a lockable differetial to your front diff. It's quite a different story:



You now have positive drive on tyres 1 (essentially useless), 2 & 4, this will probably get you out... since we have said that number 4 is on a nice solid rock and it now has drive... but if you are badly stuck this may not provide enough traction.

top post SS

Q re: diff C, in the above two pics why wouldn't there be drive to both rear wheels as they are both on the ground, i would have thought drive to wheel 3 would only be lost when traction is lost/broken at wheel 2