Steep Downhill and you need to downshift

I don't understand the rule of thumb of one gear lower going down than going up. It depends entirely on your weight. I drove Flagstaff to Phoenix for several months always at near maximum weight. I safely went down a 12 mile downgrade with some 6% sections by dropping my 18 speed one full gear, to 16th. Going up? I had to drop down to 14th, maybe 13th.

 

My question about these differing 'rules of thumb' - how do you know that the downgrade on the other side is the same % as the upgrade? I'll bet that it's not. Plus, it's weight dependent. I can go down a 6% grade empty and need to use the medium engine brake setting in 10th to maintain 60mph. Loaded, I'll need to be in 9th at max engine brake and still need to stab brake every 60 seconds to maintain 50mph.

It was safer to continue on to the nearest area where he could get the entire truck out of the travel lanes, IMO. Tough choice either way, but I say out of the travel lanes is the safest option.

 

I don't think they are saying that there's 1 rule that covers all situations. There are variables that can be taken in consideration. In many places along the interstate, the uphill climb may not be as steep for a long a time as the downhill. They will wind the uphill section around a bit more, level it off a bit more to make it easier to get up.

Also, there are some incredibly strong engines out there. A driver pushing monster horses may not even need to drop a gear to climb a mountain, even with a full load., but on the other side...? An extremely powerful engine will give you a strong as hell jake, true...but I don't believe in throwing all the eggs in a jake brake basket.

 

Everyone keeps saying "stab braking", don't you mean "snub braking"?

You generally have only one chance, maybe two, to come to a complete stop downhill with just the brakes. This is why you want to be in the proper gear. But like the OP said, sometimes you have to use that 'advanced technique' to downshift on the downhill.

Snub braking is the method where you ride the brakes about 5 seconds give or take to lose 5 miles per hour give or take then let off. If in too high of a gear I would press brakes maybe 7 seconds, down to 1000 rpms give or take and lost about 7 miles per hour say, then downshift, let it come back up 5 miles per hour then lose 7 more miles per hour if necessary, then downshift again. I call it 'modified snub braking' wherein you create a net loss in speed so you can get to that proper gear.

Couple years ago my truck derated and there was no jake brake action at all. Would go down hills in 7th or 6th then noticed it was straight gaining freakish speed. Would have to use my technique to get into 5th and sometimes 4th to hold her back.

 

I always assess the type of downgrade percentage, then I slow show to maybe the 9th or 8th gear. Always obey the posted speed limits for trucks no matter how many truckers call you a chicken over the CB lol!

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Do you guys know how a compression (Jake) brake works? The higher the RPM the MORE effective. If you need max braking power go to 2100. If you guys ever got into heavy haul, over 110,000, you would be going down the grade at the maximum speed the "Jake" can hold you back. Down shift as high RPM as you can and still make the next lowest gear. The "ideal" situation is not to have to use your service brakes on a down grade. The normal braking weight rating for 16" Rockwell Q-brakes is 25,000 to 32,000lbs. per axle excluding the steer at 15,000lbs. If you decide it has got out of hand, hammer the brakes and bring it down to control, dont wait. The statement about the trolly and when to use it is part true, until I read the post from the guy who has been in the sh#t wrote. When you are on the throttle your trailer is far less likely to roll. You really need to drive off road with things like log trailers on sliding snowy, or muddy slopes. Roger Ramjet seems to roll less trailers than the skittish. Unfortunately there was no one in that truck to help this kid.

 

Made my first solo run a few days ago to get back home.

Had to go up and down a few mountains.

Aside from the training I received (one gear down on the other side), I was trying to use common sense.

Whenever I see a sign that says "downgrade ahead" I dropped my speed and got ready for a sign that is going to give me a %.

Then when it says grade(6%) I get into 6H and make double, tripple sure the jakes are on. They hold me like a rubber band. Love the jakes!

I have a cheet sheet hanging from the dash that gives me the %/gear that my trainer said I need to be in. When I see the grade number I look at that sheet and get in that gear and just steer.

Sometimes it seems that I could actually take it a little faster but oh well, I'm already set and I am not taking it out of gear at that point.

I may take the tach up to 1700 to get another 5mph out of it when it flattens out but I will not gear up until I feel that I have reached the bottom.

The thing is, I never see a sign that says "End of downgrade". Ya' know, like "End of road work"?

I guess it's all about discretion or experience with that particular hill at that point.

I''ve been passed downhill by guys doing 10mph faster or more but I figure they know that hill.

I never hit the brakes 'cause the jakes do it all.

When it comes to snow/ice it will be a different story I'm told.

My trainer can jake on snow/ice but said that it comes with experience.

Just get in a confortable speed that the jakes will hold you at and 10-30 minutes later your down that hill and back to flat ground.