Probably a stupid rookie question.

You need to learn how to use them properly on dry pavement before applying them on slippery surfaces, but they can be used if used properly. Check out the thread that @NorthernMechanic posted.

 

These cdls schools don't teach you anything but how to pass the test to get your cdls. The real learning begins on your own

 

@northernmechanic is now @AModelCat

 

Make sure in slick conditions you do any (firm braking) while travelling straight this means you may need to slow extra before curves so as not to reach to high a speed while making the curve never (hard brake)

 

It's your truck and nobody knows it better. The advice given here is good on the most part. Feel the truck and know it's capabilities before you put it to the test going down a grade. I've hauled loads over 105,000lbs with no engine brake whatsoever. Going down I84 in Utah was long but did not ever smoke the brakes and had plenty of brake to make an emergency stop if needed. The trick is in the speed the truck is traveling down the hill. If you're going to fast you're asking for trouble. As a general rule I'd go down 35mph with the engine brake and 25mph without one. If you're loaded lighter then I would adjust the speed. You can adjust your speed when you know the truck. I don't know if you've ever been out west but there's some pretty good grades. I would haul gasoline in a super tanker and gross around 110,000lbs. Go down NV163 into Laughlin NV when it was just two lanes. That will convince going slow is better than fast. I'd see those truck going 55mph down that hill and pass them at the bottom of the grade when they had to pull over because of brake smoke. So like I said, you know your truck and do the testing on a safe road.

 

I wonder why they are saying not to use retarders, I think it breaks much softer than my foot.
Anyway, last winter I was driving for about 3 weeks in WA and OR. The freeways were nice and dry, so then I decided to take a short cut over some mountain. Couple miles away from the freeway nothing but snow and ice, no place to turn around, so I kept going up the hill, and barely made it to the top, there I stopped to ##### the situation, should I wait till summer, or risk to slide down hill. I decided to keep going really slowly, 10 to 20 mil., the retarder OFF.
When I came to my first turn, I started braking very softly, but the steering wheels blocked and I went straight, luckily I was very slow and nothing happened. But I was thinking what if I get to bigger curve or slope how do I brake without locking the steering wheels. OK I will try the retarder, I did and from then on nice smooth braking, not the slightest problem for about 15 miles all the way down to the valley.
Since then, I always use it, nothing slows the truck smoother than combination retarder and gas pedal.
I think if I should get into trouble then I was too fast anyway and in that case nothing helps me.

 

Were the jakes on low?

 

In aviation we call a private pilot license a license to learn. Same could be said for a new CDL. It's a license to learn.

 

If you apply the brakes and your truck wants to go straight in a turn, then release the brakes and it will turn nicely as the steer tires roll. Downhill you control your speed by pumping the brakes. Each application of the brakes will slow you down and you slide straight, every release of the brakes the steer tires roll and you turn. In the days before ABS I learned to do this in a car in the PNW with light, very rapid braking.

Going uphill if you start going straight in a curve ease off on the throttle to get it to turn, then get back on the throttle to maintain momentum. Again, this is pumping the throttle with small changes in in horsepower, larger as needed. This is most common when you are plowing through mud with your differentials locked.

 

That's what I do if I don't have the jake brake, and quite often I slid of the road. Even with ABS they lock and I am going straight into the ditch, when I am offroading with my private car.
But with jake brake, I like to use it. It's much smoother braking and you never loose the steering capabilities.
Also once the steering wheels lock it takes little bit time till they start rolling again, and that fraction of a second in those situations always seem to me to last an eternity.
And also didn't had any room to slide around.