edwinsmith

It seems to me that if you're pulling a trailer or a 5'er in the rain with an exhaust or engine brake the trailer would be prone to jack knife. Does anyone have any experience with this problem?

Edwin

RustyJC

Yep, be careful using the exhaust brake in slick conditions. I use it in the rain, but I'm ready to hit the clutch should things get squirrely. It's not really that common with the pin weight I'm carrying.

Rusty

Moose10

So Rusty you're saying that the heavier the pin weight, the less likely it has a chance to jack knife?
I'm very hesitant about using it in the rain or when there may be the chance of ice on the road.

Homestead

You get a "feel" for the exhaust brake when you have used it enough.

I use mine everyday winter, spring, summer and fall. It just becomes habit when and where to use it. Crossing a bridge and slowing for the off ramp at the end in winter conditions, usually not a good idea to use the brake.

Had a couple of occasions when the wheels locked up while towing, but i use a shifter mounted switch so I can shut it down real quick if need be.

Exhaust brakes are pretty forgiving.

thecatsfan

For just rain, I have no second thoughts about using my exhaust brake. 22 years of winter driving in the rockies and rain doesn't seem that slick to me. Sheet ice over the west side of Wolf Creek pass - that's slick.

But like any driving in bad conditions, you have to be driving the proper speed to keep everything under control. You can't wait until things get ugly and then try to slow down. That's how most people get in trouble. From my limited experience, if you are driving at the proper speed for the conditions, the exhaust brake is no more likely to cause any skidding than regular brakes - at least not in rain. If that were the case, then gas engine trucks would be in trouble every time they downshifted in the rain.

majora

I suppose that you could have strange things happen if you allow the engine to go to idle and have the brake engaged prior to downshifting. I can chirp the tires on my truck if I do this. Normally I hold the rpm up enough that the exhaust brake is not engaged until the shift is completed. And yes, my brake is activated all the time, loaded or not. Got 96k miles on the factory brakes on my 96 CTD with brake so it helps.

RustyJC

Frictional force between two surfaces is determined by vertical weight applied [the more, the better], the coefficient of friction between the surfaces [the higher, the better] and the surface area [this one is touchy].

Theoretical physics says that less tire area is better in some respects as it produces higher unit loading (higher lbs/sq in - constant weight distributed over fewer square inches of contact area). This may be true under wet or snowy conditions where the higher unit loading promotes the tire cutting through the water or snow for improved traction - in other words, a SRW truck carrying the same pin weight may exhibit better traction in the rain than my dually which has about half the unit loading on the tires, so the dually's tires will have more tendency to "float" on top of the water, or hydroplane.

Under dry conditions, however, behavior doesn't conform to the oversimplified sliding friction model. That's because there is actually a mechanical "lock" between the tire and the road - the soft rubber on the tire conforms to the irregularities of the road surface. This makes the mechanism behave more like a geartrain with a pinion (tire) made of a material with low shear strength engaged into a rack (the road surface). In this model, the more surface area, the more tractive force that can be transmitted before the pinion's gear teeth get sheared off (i.e., the tires lose traction). This explains why drag racers, road racers, etc. want wide tires with no tread (maximum surface area) in dry conditions, not bicycle tires as theoretical physics might seem to encourage. Rally cars are another matter - they use tall, skinny tires to cut through snow, gravel and the thin layer of water on top of ice.

Rusty

Moose10

Thanks Rusty for the detailed explanation
I should have specified that I'm more hesitant with the brake now in poor road conditions with the fifth wheel. I used to have a heavy slide in camper, and used the brake almost exclusively year round.