Mountain Driving Without Engine Brake

Generally you want high rpm going uphill (for power in case trailer starts to slide you can pull it)

I disagree, you want low rpm going uphill. There's a much greater chance of sliding and/or losing control climbing a mountain with high rpm.

I understand your point as well Daniel. What about descending, anything else to offer on that?

Generally you want high rpm going uphill (for power in case trailer starts to slide you can pull it)

I disagree, you want low rpm going uphill. There's a much greater chance of sliding and/or losing control climbing a mountain with high rpm.

I understand your point as well Daniel. What about descending, anything else to offer on that?

Well I do them a bit different I think. Since I drive a LW truck I usually have 44-49K in the box and a smaller engine so I have less braking effect of the engine. 2000 rpm' doesn't even hold me back it seems.

It handles so much different than the trucks you folks drive.

I take it no faster than 15mph on iced up roads with low rpm to give me room to accelerate lightly should I start losing the trailer. I usually don't need to use the brake but if I do I feather it.

I picture an egg under my brake pedal, if I press too hard the egg cracks.

I picture an egg under my brake pedal, if I press too hard the egg cracks.

My one instructor used to say that.

Back to something else you said, you mentioned you don't really have to use the brakes. Were you talking about descending as well? With a low rpm descending a grade, and a low speed, you're saying you still don't really have to use the service brakes - and that's w/o using the engine brake too? I thought that having a higher rpm is what helped the engine naturally retard your speed when descending a grade.

I definitely use a lower RPM when descending a hill in the snow and ice. Everything is slower and more careful, kind of like I stated earlier. I'm not sure I could give you accurate numbers as I tend to use my ears more so than my eyes when determining my RPM levels - if it sound right I'm good. The thing about bad weather is that you want to spread out your resistance to the gravitational forces of the descent to all your axles, not just using the resistance of your drive axle. The only way to do that is to use the brakes. That's why everything is done much slower - you want to avoid overheating those brake parts. If you are running downhill at a high RPM on snow and ice your drive axle is much more likely to break loose and start into a slide.

Just take it slow and don't ever get concerned about those nuts that will go flying past you - in about thirty minutes you will be passing them as they are standing outside in the cold looking at their rig, scratching their head and trying to figure out why it is in the ditch!

I picture an egg under my brake pedal, if I press too hard the egg cracks.

My one instructor used to say that.

Back to something else you said, you mentioned you don't really have to use the brakes. Were you talking about descending as well? With a low rpm descending a grade, and a low speed, you're saying you still don't really have to use the service brakes - and that's w/o using the engine brake too? I thought that having a higher rpm is what helped the engine naturally retard your speed when descending a grade.

Yeah, because I'm going so slow and at such a low gear that I simply don't generate enough momentum to speed up much. I obviously have to use the brakes here and there but not much.

Unlike OS, I use my eyes and ears when descending. That's just my way. But then again, OS primarily uses his ears because his eyesight isn't what it used to be when he was a young adult 118 years ago.

Unlike OS, I use my eyes and ears when descending. That's just my way. But then again, OS primarily uses his ears because his eyesight isn't what it used to be when he was a young adult 118 years ago.

I do find that he also tends to repeat himself a lot in his posts. Perhaps his mental acumen is failing as well as his eyesight ...

You know I'm kidding, Old School.

I disagree, you want low rpm going uphill. There's a much greater chance of sliding and/or losing control climbing a mountain with high rpm.

So what you're saying is that at lower rpm's with more torque and less horsepower you're more likely to break loose?

I just want to make sure I am understanding you correctly as it is totally opposite what I have read and was taught in driving school.

I disagree, you want low rpm going uphill. There's a much greater chance of sliding and/or losing control climbing a mountain with high rpm.

So what you're saying is that at lower rpm's with more torque and less horsepower you're more likely to break loose?

I just want to make sure I am understanding you correctly as it is totally opposite what I have read and was taught in driving school.

I got that backward... It should be So what you're saying is that at lower rpm's with more torque and less horsepower you're less likely to break loose?

I didn't catch it on the preview...

Here's a few things from the winter driving handbook I got in CDL school:

Before going down a grade in winter...

Make sure the power divider (axle lock) is released going downhill. A free rolling wheel that is not receiving power or braking is less likely to slide.

Select a speed and gear that gives you the ability to go slow enough to stay in control and yet have the ability should you need it to let off the brakes or accelerate slightly to pull a sliding trailer back in behind you.

The important question is where are your RPM? Are they high in the range or low in the range? This is what you need to know when you are going down a grade. Once you are at a safe, manageable speed, then you need to think about whether or not you have torque.

You have high torque in the low to mid rpm range, and high horsepower in the high rpm. If you are in the high torque range, you have the ability to PULL, so if the trailer happened to get out of line and you were in high rpm the only thing you could do to speed up and get out in front of the trailer would be to upshift, and you would not want to upshift if your trailer is trying to push you off the road. If you push in the clutch to shift at this point, or brake, you lose the pull on your trailer and can make the trailer skid worse. That is why when going down a grade you keep your RPM in the mid range so you always have the ability to pull when you need it without having to upshift. Be careful not to go too low (below approximately 1000 rpm) in the torque range when going downhill with a heavy load as this could also cause a skid. Some engines have a lower torque range so make sure to look at the manual for the vehicle you are driving.

Going Uphill

In order to understand the proper technique for going up grades on a slick road, you first need to know what causes a drive axle skid. This is the most common type of skid drivers experience when pulling a slick grade. When you understand what CAUSES it, then learning how to PREVENT it will make more sense.

To prevent a drive axle skid you need to stay out of the torque range when going up a grade. To stay out of the torque range, keep RPM high. When going uphill, staying high in the RPM range also helps to keep your engine from overheating by allowing it to draw air through the radiator and cool.

Remember these techniques by thinking UP HIGH and DOWN LOW.

At first it may feel funny pulling a grade at high RPM. However, you are using that extra fuel to prevent an accident. It is a very small price to pay for the benefit.

Ok I won't copy the whole thing. I should mention that different engines have different no load governed rpm's, but the rpm's used in the example showed about 1400 being in the torque range and downshifting before going up the grade to maintain about 1800 rpm.

I hadn't read this since school, so I didn't remember the exact rpm's it mentioned. I usually maintain about 1500-1600 going uphill, so I might have to change that. The main thing is that you want to be in control of your vehicle, whatever that means for the individual driver.

As for dry roads, it doesn't seem to matter what the rpm's are, you just want to be in a low enough gear. If you are heavy enough you are going to use the brakes.

...which also makes me realize that although I had remembered the basics of UP HIGH / DOWN LOW, I was incorrect in stating you wanted the power to pull uphill and the torque downhill... it's about having enough room to accelerate downhill if you need to whilst NOT being in the high torque range, and being above torque range going uphill.

Also, when I said...

" As for dry roads, it doesn't seem to matter what the rpm's are, you just want to be in a low enough gear. If you are heavy enough you are going to use the brakes."

... this is in regard to NOT using the JAKE brake. Higher RPM does affect the jake brake.