"Trucks use low gear"

You know, I've never looked at it that way before. I've always interpreted it to mean if you had just pulled up that hill, what gear would you be in vs. going down the other side.

 

That use to be the general rule when trucks weren't as aerodynamic...now it's 1 gear lower than you climbed if lite, 2 gears lower if heavy.

Here is a thought for truck makers...all these aero enhancements that make you slippery to the wind while rolling need a reverseable switch to increase drag when decending. Planes do it when landing, the 'air brake' tail on a Bugatti Veyron produces more braking than an economy car's brakes..why not something like that on a truck...

 

I never would have guessed that. I figured it'd stay the same since the jakes have gotten a lot more powerful in newer trucks. I remember my dad telling me when he traded his '03 C-15 KW in for an '07 ISX KW that he could come down hills a full gear higher and be on the brakes less than with the older truck.

 

In the old days before jake brakes were standard issue on these trucks, you'd want to down shift a few gears lower than your normal cruising gear, so the engine breaking effect takes hold.

Now you can probably ignore those signs and go down in the same gear you came up in, with jakes on full blast of course.

 

Northern, some of that I think is just the nature of the engine manufacturer.... All the Cummins's that I have run have held back way better than the Cats I have run.. but all the Cats have out pulled the Cummins!!!

Now if you've never been down it before, might be best to drop a couple, I know of a few that you think your good, come around a corner and then comes the pucker as you notice the next corners sharper and leaning the wrong way Hang on as the ol girl leans,, a lot!!

 

The CDL manual's answer is "1 gear lower than the gear used to climb the hill"

So I guess if you only have to go down a grade and not up the other side you should hammer down the hill, turn around and climb back up it. Then you'll know what gear you should be in to go back down it in a safer manner.

 

In today's neutered trucks we would end up with a bunch of idiots going down a 4-5% grade at 15 MPH... CR England And Prime drivers read these boards can we please try not to make them more of a Hazard on the road.