Hills/mountain descending?

Thanks, but our opinion doesn't matter since were just the outlaws that use jakes int he rain lol

 

Not much too add, but I hate doing unfamiliar grades at night. So whenever possible I run them in the daylight.

I just did one today, twice, both directions. Posted truck speed was 20 MPH. First time I went down I used 6th gear and had the jake at its lowest setting. I had to turn it off a few times and on a flat spot went up to 7th for the rest of the way and never had to touch the service brake.

In this case it didn't matter what my load weight was as the speed for all trucks was the same, 20 MPH. I got passed by a lot of trucks going much, much faster. But I didn't care, because I never ran this hill before and it had lots of turns.

On the return trip I was lightly loaded and started out in 7th gear. I have 3 settings on my jake so I used the jake and never touched the brake.

With only 2 years of OTR experience I will not second guess what the more experienced members have already offered, especially since it all matches with what I was taught and fits with my experience so far. I mostly just wanted to add the daytime night time factor to the discussion.

 

Thats just stupid. You do relize your tires are only rated for upto 75mph. The chance of a blow out goes up exponentially with every mph over 75. If you blow a steer at 80 mph, your done. That truck is gonna roll and at 80 MPH your not gonna be able to control it. Now at 75 your odds are pretty bad for controlling after a blow out, but your blowout risk is way lower. Also, on a steep grade with a heavy load, a truck could easily go over 100 without jakes. lastly, unless you can see the bottom, how do you know there are no turns.

There could easily be a pot hole you need to steer around, road debry, road kill etc. You wont be able to at 80+ mph. If you try to use your brakes, the tire will quit being round at those speeds and start to lean forward. Over 75 is just asking to have serious problems.

 

I may not be a rocket scientist like some of these guys on this forum but my simple suggestion is to slow the #### down. That's pretty much it. Find the right gear and stay there. When you approach Cabbage Hill on I 84 in OR, there's a huge sign that recommends a speed depending on your gross.. If you're 75000-80000 gross, the sign says 18 MPH. I'm not making this up. OK, that's assuming you don't have a jake. With a real jake, Maybe 40. On the northbound I-5 over the Grapevine, the mandatory limit is 35.

 

Dont forget, jakes have been known to fail half way down a hill before....you do want to use it as a tool, but wanna be going slow enough to be ok if it dies

 

thats my way I'm sure you will do somethings i find stupid. to each their own

 

I don't do anything that unsafe or illegal. i certainly dont suggest its ok to run like that when a new driver is looking for advise on how to run safely. If you blow a steer going that fast "your way" could kill others, not just you.

 

What's crucially missing from this discussion is elevation.

The higher you go, the thinner the air. The thinner the air the less engine braking you have because pistons aren't pushing against as much air resistance. At high elevation, your turbo doesn't even kick in until 1500 to help pressurize your system. If you listen, at high elevation your turbo doesn't kick in as it does at low elevation at peak torque.

Now, if you're driving a Gordon truck, the Gordon Way forbids you to run the RPM over 1500 and you just have to throw that part of the Gordon Way out the window. But you still have to abide by the Gordon Way 65 MPH speed limit. That includes down from Eisenhower Tunnel, into Vail and Glenwood Canyon, for example. (Current truck is ungoverned but I still stay 5 MPH under posted downhill speed unless I know that hill really, really well.)

The way we were told to do it years ago, and which much signage is a hold over from (for example Cabbage, Meacham), is that business of same gear at the top, Johnson bar at a steady 2-3 pounds, downhill speed depends on your gross load. You can still smoke your brakes that way if your engine isn't helping you because you're running your RPMs down at 1000-1200. (How do I know??? Don't even ask, okay... )

It worked in the old days with the standard of the day Cummins that shifted at 1800/2200, down at 1800, up at 2200. Those old engines were pumping, had no power below 1800 where you could break the engine by 'lugging'--adding pedal into low RPM. At 1000-1400 RPM of a modern ISX, in thin air your engine can't help you. Not enough pressurization, air resistance. Air's too thin.

So if you're lucky enough to have an engine brake with multiple levels (at least 3, for example), you can choose the speed/gear you want (for example, to stay under the Gordon Way 65 MPH speed limit even on a downgrade), but each gear's gonna get you more MPH because your RPMs are up above where you would normally run...

Which is why you can come down a major grade at a conservative 45-55, even 60 MPH (after some experience on that hill) without touching the brake and just changing your engine brake level. Up to 3 at 1800, down to 1 at 1500 and repeat on down the grade. Feels like you're shifting gears, too. Snug as a bug in a rug. Very cool. Very exhilerating. In complete control. Your service brakes cool and untouched and on reserve in case you need them...

 

If you go looking thru old threads you will find a lot of advice concerning brake management and gears.
The most important of them is go at your own pace don't let others ouch you into something you are not comfortable with