Did some experimenting with lockers locking during wheelspin (1 Viewer)

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The local Hummer dealer has a mini obstacle course behind the dealership to showcase their abilities. The gate is always open so I go through it whenever I'm in the area. The most difficult part is a device with steel rollers that has an uphill hump and only a single tire is on cement. You won't get through it without lockers or an electronic locker designed for offroading.

Today I realized it was a way to experiment with locking the factory lockers while the wheels are turning to see what happens without having a dangerous load on them. I was expecting at least a metallic twang or clang but was pleasantly surprised. With one rear wheel at walking speed (5mph) and the other stationary I engaged the rear locker and kept a bit of throttle on - progressively higher and higher. At some point the stationary rear wheel began turning and then I heard the click (windows down) of the locker engaging. No drama, no grinding engagement and the Cruiser popped right out of the little trap they'd built over and over.

So it gave me a little confidence that in the future if I'm stuck in snow I can be a little less conservative in locking them up as there must be something in the actuator that ensures they're either fully engaged or fully disengaged even under power. The actuator must have enough power that once the splines are lined up it can jam the locker together so the splines are fully engaged in an instant.

I did it several times with varying speeds and throttle settings and after a dozen or so it was clear the engagement was clean and snappy every time. This was a unique opportunity to engage the locker with wheelspin under controlled conditions.

DougM
 
Did the hill look like this?


YouTube - Eaton Locking Differential Demonstration


Or did it have multiple roller patches on both sides?

I remember seeing a Unimog testing video where they had multiple roller patches on each side with staggered placement so there's absolutely no way of getting up unless you had both front and rear lockers :doh:
 
Technical question about mimicking lockers: Why not apply some brakes while you try to drive out of the slippery spot? In theory applying the brakes supply resistance to all 4 wheels, so that the differentials don't "see" any wheels on slippery surface. Equal distribution of "spinniness" = go forward power.

Do you guys see any problems with this approach besides extra brake and tranny wear?
 
Technical question about mimicking lockers: Why not apply some brakes while you try to drive out of the slippery spot? In theory applying the brakes supply resistance to all 4 wheels, so that the differentials don't "see" any wheels on slippery surface. Equal distribution of "spinniness" = go forward power.

Do you guys see any problems with this approach besides extra brake and tranny wear?



Our brakes aren't applied evenly to each wheel, not that it would work anyways....

Now, if there was a controlled, individual wheel brake application (like with FJC's A-Trac), then it would work, but still not as good as a proper locker....
 
Technical question about mimicking lockers: Why not apply some brakes while you try to drive out of the slippery spot? In theory applying the brakes supply resistance to all 4 wheels, so that the differentials don't "see" any wheels on slippery surface. Equal distribution of "spinniness" = go forward power.

Do you guys see any problems with this approach besides extra brake and tranny wear?

Used that technique a lot in the snow back east. No substitute for lockers, but better than nothing.
 
Technical question about mimicking lockers: Why not apply some brakes while you try to drive out of the slippery spot? In theory applying the brakes supply resistance to all 4 wheels, so that the differentials don't "see" any wheels on slippery surface. Equal distribution of "spinniness" = go forward power.

Do you guys see any problems with this approach besides extra brake and tranny wear?


With a Torsen type diff, this works. Even though you're applying braking force to both wheels, the helical diff gears multiply the torque from the spinning wheel and you net some torque to the wheel with traction.

In an normal open diff, you're getting the same torque to both wheels and the same braking force, so you don't really net much of any torque to the wheel with traction.
 
Snake,

It's much worse than that video. It has two roller patches for the rear wheel, and one roller patch for the left front wheel. The left front roller patch is sloped upward with an abrupt lip of rollers as well. It's pretty devious and you are not getting up it without an excellent traction aid such as a locker or a traction control system designed for offroading.

So, only the right front tire is on pavement and it also slopes upward with an abrupt lip. I can get over this easily with just the rear locker engaged as the center locker is also engaged.

DougM
 
...

Today I realized it was a way to experiment with locking the factory lockers while the wheels are turning to see what happens without having a dangerous load on them. I was expecting at least a metallic twang or clang but was pleasantly surprised. With one rear wheel at walking speed (5mph) and the other stationary I engaged the rear locker and kept a bit of throttle on - progressively higher and higher. At some point the stationary rear wheel began turning and then I heard the click (windows down) of the locker engaging. No drama, no grinding engagement and the Cruiser popped right out of the little trap they'd built over and over.
...

That's the way I have been using them for years, go until there is slip, allow the wheel to slowly slip and hit the switch, they lock right up. When clear click off, even on pretty tecnical trails only use them for a few feet over the whole trail. May try to keep track of about how many feet, on Spike next week.
 
Technical question about mimicking lockers: Why not apply some brakes while you try to drive out of the slippery spot? In theory applying the brakes supply resistance to all 4 wheels, so that the differentials don't "see" any wheels on slippery surface. Equal distribution of "spinniness" = go forward power.

Do you guys see any problems with this approach besides extra brake and tranny wear?

I believe this is the trick used in the Humvees, I remember being trained on this many moons ago...:D
 
Technical question about mimicking lockers: Why not apply some brakes while you try to drive out of the slippery spot? In theory applying the brakes supply resistance to all 4 wheels, so that the differentials don't "see" any wheels on slippery surface. Equal distribution of "spinniness" = go forward power.

Do you guys see any problems with this approach besides extra brake and tranny wear?

yup, that can work some, depending on traction, torque you apply etc. Gotta hit it just right for the conditions though, and may not always work. No comparison with real lockers, of course.
 
On the original Humvees they had axle lockers in each hub (I believe) and with the power on you jab the brakes and the lockers lock up. That went away 5 years or more ago when they brought in the electronic traction control stuff. I drove both at the Hummer Factory in Indiana years ago - they have an obstacle course about 40 times bigger.

DougM
 
Like I said... I drove one of those things many moons ago, maybe 15 + years ago.:D
 
I tried the brake trick when stuck this winter, I heard a slightly different version though using the ebrake to lock the wheel, I can see how it would work however it did not get me unstuck while giving throttle I pulled on the ebrake, the spinning wheel stopped and the other wheel dug in, the 80 sunk deeper in the snow and both wheels would spin freely. This did give me some hope that an auzie in the rear will be worth while.. now if I could just sell the 60 and my 2wd so I can start modding the 80 and for those of us without lockers why not just run up the roller ramp at speed if you can jump across the rollers because of momentum no time for the wheel to slip agt least that is how I get up slippery gravel hills now
 
Military HMMWVs have torsen diffs. BTM (brake-throttle modulation) is the way to get all 4 "locked" in low traction. Just NEVER stab the brake with your foot on the gas and a wheel spinning. You'll snap a stub shaft or a spindle. Ask me how I know ;)

BTM is an aspect of left foot braking techniques. Steady throttle foot, use brakes to ease into or onto obstacle and regulate speed. Throttle keeps torque up without acceleration causing loss of traction (wheel spin).
 
BTM is an aspect of left foot braking techniques. Steady throttle foot, use brakes to ease into or onto obstacle and regulate speed. Throttle keeps torque up without acceleration causing loss of traction (wheel spin).

So you're pretty much two-footing it? I knew that had an application in wheeling...
 

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