Community Forums

scotttkd · 09-29-2022, 03:38 PM

2020 Newmar Kountry Star, Cummins ISB 6.7 and Allison 3000 6 speed.
Had a situation where right rear wheels had gotten into soft mud and were spinning, left rear (and front) on dry pavement, but left rear would not provide any power either reverse or forward. Got a gentle pull out/assist from a HD pickup and a tow strap attached to the tow bar and managed to ease it out and went on my way.

Question, I swear when later looking for something else totally unrelated I came across a claim that there is a transmission setting that would have "locked up" both wheels and provided power to the non powered left wheel as well as the slipping right wheel. I have searched high and low and can find no reference to it.

Do any of the Allison experts here have any info??

Thanks in advance!

Scott

Jon_C · 09-29-2022, 08:17 PM

What you’re describing is a differential locker. It is inside of the axle. My Jeep Rubicon has both front and rear lockers, when locked both wheels receive equal power. I doubt any motorhomes would have one.

A motorhome will probably have either an open differential or a limited slip differential. With Open differential, all power is sent to the wheel with the least traction, similar for limited slip except there are clutches inside that will automatically send some power to the non slipping wheel as well.

scotttkd · 09-29-2022, 10:08 PM

Thanks for the detailed answer, I was afraid that was the case, but I thought for sure I read something somewhere. It was frustrating being stuck with the entire driver side of the coach on clean dry asphalt. Oh well, another lesson learned in the rv life....always carry tow straps.

Caliber · 09-30-2022, 06:17 AM

Research "ATC" automatic traction control. It's a feature of the "ABS" system. If your coach is equipped with this option. It applies the service brake to the wheel that has less traction forcing the differential to turn the opposite side wheel.

MtCamper · 09-30-2022, 06:34 AM

The old trick for that one is to apply the brakes and throttle at the same time. Hopefully it allows the transfer of some power to the traction side. Doesn't always work. Whatever you do, don't tow with sudden acceleration unless you are using a kinetic rope. Never try it with a chain, cable or non-kinetic strap.

scotttkd · 09-30-2022, 09:51 AM

Caliber....after reading your description I think that is the info I had stumbled into but couldn't remember where. I have ABS, but not sure if it has the ATC. Doing more digging, but now I know what I am digging for!

Thanks guys!

Scott

scotttkd · 09-30-2022, 09:53 AM

Quote:

Originally Posted by MtCamper

The old trick for that one is to apply the brakes and throttle at the same time. Hopefully it allows the transfer of some power to the traction side. Doesn't always work. Whatever you do, don't tow with sudden acceleration unless you are using a kinetic rope. Never try it with a chain, cable or non-kinetic strap.

Yeah, we used a woven strap, took up slack and then put mine in reverse, and the HD truck just gently applied power (It was on solid asphalt) and it eased right out.

Jon_C · 09-30-2022, 04:12 PM

Quote:

Originally Posted by scotttkd

Caliber....after reading your description I think that is the info I had stumbled into but couldn't remember where. I have ABS, but not sure if it has the ATC. Doing more digging, but now I know what I am digging for!

Thanks guys!

Scott

In the 4wd community ATC is the first thing turned off when going off-road, most systems cut engine power when a wheel spins, this would help on road but the last thing you need when your trying to not get stuck or get unstuck.

As mentioned easing on the brakes and throttle helps transfer some power to the spinning wheel

scotttkd · 09-30-2022, 04:21 PM

Jon_C....I don't have my RV in hand until next week, but I am finding no reference to the traction control in the info I have on hand. I was hoping if I have it I can find out how to disable it if I get into a stuck situation again. It was so frustrating to see a wheel on dry asphalt doing nothing while the one in the mud was spinning. Thanks for the input.

777 Driver · 09-30-2022, 05:14 PM

My '18 Entegra Anthem (with Automatic Traction Control) manual contains this statement:

Automatic Traction Control
Enables increased vehicle stability to prevent loss of traction. (Generally left in the ON position but turned off when in snow or mud).

Take care,
Stu

twinboat · 09-30-2022, 06:13 PM

Quote:

Originally Posted by Jon_C

In the 4wd community ATC is the first thing turned off when going off-road, most systems cut engine power when a wheel spins, this would help on road but the last thing you need when your trying to not get stuck or get unstuck.

As mentioned easing on the brakes and throttle helps transfer some power to the spinning wheel

I have ATC on my Honda Ridgeline and ATS does more then cut power. Actually I have a Snow button that cuts power.

It's FWD and while pulling thru mud you can feel the ATS working as it applies one brake or the other depending on wheel spin.

MemByTheMile · 09-30-2022, 07:41 PM

Some motorhomes do have the feature to lock the differential. Typically on SuperC models that are built on medium or heavy duty truck frames. On dual twin screw heavy duty frames you will have the option to not only lock the left and right together but also lock both rear axles together.

It is a very nice feature that has helped us a couple times.
Would be great if the diff lock was available on most MH chassis.

Jon_C · 10-01-2022, 09:11 AM

It's FWD and while pulling thru mud you can feel the ATS working as it applies one brake or the other depending on wheel spin.[/QUOTE]

Thats called brake lock differential in the Jeep world, im pretty sure it only available on 4x4 off-road vehicles. On Jeeps its only active in 4hi or low range.
ATC only available in 2wd or 4hi and can be disabled by pressing the traction ctl button but BLD stays active. A long press of the traction ctl button turns everything off.

https://www.wranglerforum.com/thread...lained.803194/

https://blog.stellantisnorthamerica....rol-explained/