Power Divider/Inter Axle on Ice

Why would you lose control with the IAL engaged? Please elaborate.

 

Sounds to me like a lot of people are talking out their rear. Locking it will not cause you to loose control. It will only help you maintain traction. Having the jake brake on at any level on icy roads will cause you to lose control. I don't run with mine locked all the time. I determine using it by the weight of my load. Heavier weight the less I need it. But I am quick to shut off my jake.

 

I run a single drive axle in the rain and snow all the time in UT & NV and use the jake all the time..Jakes are way better than hitting the petal to slow down...I'll use the jake while chained up too...When is the dont use your jakes myth gonna die

 

You will slide on ice alot quicker using the petal brakes before you do using the jake brake..Think about it..A jake is an engine brake that slows your roll..When you apply your brakes the pads expand in the drums and the idea is to stop the tires from spinning then you slide..ever see four wheelers sliding down the with the brakes locked up ?

 

It's physics. You are much safer with it off, especially if the road is not level side to side. Less likely to jackknife.

 

your more likely to slide with jakes then pedal.

think about it. one axle or 4 axle brake vs. all 10 axle brakes. jakes only provide brakeing to the drives. the pedal provides ALL axles.

never use your jakes on ice.

i had my jakes on one time. coming down the 90 just as i crossed into montana eastbound. hit a spot of ice and the truck slide sideways. almost hit the concrete barriers set up for a construction zone.

i use jakes with chains. but not without.

people that think the jake is more safer then the pedal. need their heads examined.

 

Only engage your power divider when there is not enough traction available to get your truck moving when stopped. It is generally not needed after you're already moving. It can be useful for climbing grades in low traction situations when you don't have chains, but then you should probably be using chains anyway if conditions are that bad.

You don't want to use it on surfaces with good traction. If your tires can't slip on the roadway, engaging the power divider will put your rear axles in a bind against each other until the stress becomes so great that one tire breaks loose and relieves it. Your fuel economy will tank (pun intended), your rears and drives will experience significantly increased heating and wear, and you will have problems with understeer and steer tire scrubbing on turns.

Don't engage it or disengage it while one or more of your tires is spinning freely. If that is the case, stop the drivetrain completely and then move the selector switch. The power divider can grenade if you try to engage it when a wheel is spinning.

Don't use your engine brake on low traction surfaces. Ever. The risks outweigh the benefits.

 

Think of it this way. If you've ever driven a car with posi-traction, when both rear wheels spin, you are most likely to slide to the side. If just one wheel loses traction, it will just spin and not kick the rear end out. Engaging the PDL does the same thing. If you lose traction, it will have a tendency to kick the rear of the tractor out sideways, under jake or acceleration. Take it from someone who's spent 35 winters in a truck. The PDL was used only to get unstuck, and once rolling, I disengaged it. I've had scary rides when the PDL was engaged and lost traction.

 

Holy nonsense in this thread. I'm surprised some of you haven't also blamed the inter-axle differential (IAD) for being overweight, male pattern baldness and erectile dysfunction.

I'm with Pinner and Prairie Boy; in winter the IAD gets locked in if I even remotely think it's going to get slippery and stays in for all road types, conditions and speeds. Between the three of us: in excess of 100 years of driving over hundreds of thousands of miles of running up and down roads in the worst winter conditions imaginable; northern Alberta, northern BC, the Northwest Territories, Yukon, Alaska, freezing rain on the Alaska Highway, freezing rain on I-84 in Oregon (one of the slipperiest road conditions I have ever driven on... it was sure lonely) ice roads, lease roads, mat roads, water over ice, mountain roads, logging roads, mines, no roads, you name it... Every type of trailer and load configuration you can think of and probably some you can't, from bobtail to 200,000 lbs+... No chains, some chains, all the chains, never enough chains... I have NEVER experienced nor heard of any situation where not having the IAD locked in slippery conditions would be better. EVER.

Under normal conditions the engine's power is distributed evenly to all four drive sets on a tandem-axle tractor. However, the truth is that the power is going to the wheel set(s) with the LEAST amount of traction. If you are on dry pavement the traction to all four drive sets is fairly even and the coefficient of traction, even to the wheel set with the least traction, is high enough that it won't slip. Now, when slippery conditions are encountered all the power gets delivered to the drive set with the least traction = wheelspin. That's because the IAD functions like an open differential and the power will ALWAYS seek the path of least resistance. EVERY TIME. So now, instead of four drive sets turning, you have one. That's bad.

Locking in the IAD ensures that the power is delivered to both axles. This way, even if you're on a low-traction surface, the engine power is going to at least two wheel sets instead of just one. Now you have 50% "traction" instead of 25% with one. Further locking up the drive axle differentials (if so equipped, under proper conditions and speed) increases the available traction to 100%. In this case, more is most definitely better. Turning a corner with your drive axle differential(s) locked will result in front-end push and may require the driver to unlock the drive axle differential(s), but I have never encountered this with the IAD locked.

As for an IAD making things worse, being bad on crowned roads or sending you into the ditch, that's just... wrong. MORE traction is better.

The sliding wheel ALWAYS leads. It doesn't matter if that wheel is sliding due to acceleration or braking it always wants to lead. That's why the rear end kicks out if a wheel is spinning or sliding... it wants to get to the front. It doesn't matter why the wheel is spinning, whether under acceleration or braking; if you lose traction on a rear wheel it will want to lead and will try to come around, but will do so following the path of least resistance. So, on a highly crowned road the rear of your vehicle is heading for the ditch. Once again, more traction is better. Having the engine power distributed over 50%, or 100% of the drive wheels is always better than 25%.

Another factor to consider for keeping the IAD locked in slippery conditions is the damage than can occur to the IAD itself. The worst condition possible is if the rear axles are turning, but the front is not. This results in poor/no lubrication to the IAD itself and can very quickly lead to severe damage.