300 - 600 - 900 split downshfitng floating gears

Set them to keep the air off of the drums and shoes so they don't burst into flame. If you don't set the brakes how do you plan on stopping and holding on the shoulder of a down hill grade? Standing in front and pushing against the bumper? ROFL!

 

It's really not that big of a deal and it will be explained to you before you're asked to do it, and even then you'll get a few tries at it. The point of the training is to show you that it's not difficult to downshift going downhill and to give you some extra confidence on downgrades. That way if you end up in too high a gear you won't panic and you'll be able to keep the truck under control without any trouble at all. And it's not something you'll have to do often at all but it will help to know how just in case. Most times you know what gear you need before headed down a grade but sometimes you won't. I've driven across plateaus and come to a downgrade I wasn't expecting with absolutely no warning and I've seen more than a few steep hills with no signage at all. Trucking isn't just interstates highways with 6% or 7% limits--there are US and state roads with 9% downgrades. Jake brakes are nice, but what happens if your Jake fails and you don't know how to go down a hill without one? As far as I'm concerned the more you know the better off we all are.

It works like this: on flat you up or downshift with about a 400 rpm split, meaning to downshift you need to raise your rpms by 400 and to upshift you need to let the rpms fall 400 before putting the stick into the next gear.

If you're going uphill, and you need to downshift you only need to raise the rpms by about 300.

If you're going downhill and you want to upshift you only need the rpms to drop 300.

If you're doing the dreaded downhill downshift, you just need to raise the rpms by 600 in order to get into that next lower gear. Of course, if you're already at 1600 rpms you're not gonna be able to raise another 600 (that would put you into the redline at 2200.) So you need to drop your rpms down to around 1000 before attempting to downshift, and that means you'll have to brake in order to get the rpms down. Do the braking relatively hard and fast and get it over with so you can get off the brakes. You don't want to ride the brakes and slowly take the rpms down because you'll heat the brakes more than necessary. Get on and get off so they can get some airflow and they'll stay cool.

It's all easier than it sounds so don't sweat it. The most important thing is knowing how the transmission works so you can make it work for you.

 

And you're gonna want to use the clutch on a downhill downshift; it'll make it much easier.

 

ahhh autoshift, stick er in hold and let er buck!

back when I did drive a 13, I would stop at the top (most places you have to anyway) and keep up shifting until the jake didn't slow the truck down anymore. To hell with those guys doing 80 down the 7%. Most of the grades I went down (I know, it's not many) the posted speed limit was pretty much a match to what my jakes with the occasional brake stab would keep me at.

I remember my first grade with a real load. I was crossing into TN from NC on I-40. It was dark, couldn't see anything, had a line of 5 trucks behind me. Somebody said "Someone scared up there?" Another driver chimed in "Maybe it's called respect, driver." I let them all by as soon as there was a pull-off.

 

Where did that come from?????

 

Threads like this are the reason I believe all CDL schools should be required to have simulators . God knows they've taken in enough tuition to buy hundreds of them . Even better would be to have simulators at state DMV's for CDL testing . Don't give CDL's to people that have never been on a grade that required shifting or never driven in adverse weather conditions .

 

They should have full road courses on site too. Not some silly parking lot.

 

The original poster assumed you floated the downhill downshift. You don't, you use the clutch. And you don't gradually raise the rpms, you do it quickly and hopefully precisely. You want to nail it first try.

 

you dont float a downhill shift?
i do

hell im not sure what the clutch is needed for outside of 1st and reverse







newbies.......dont worry about grinding them, they'll make 'em outta rubber next year....just get her in a gear

 

We're talking about a new driver here in a training situation. He's gonna want to use the clutch on a downhill downshift because:

1. The trainers want to see the trainees using the clutch

2. With little experience, the shifts will be much easier to execute with
the clutch.


Besides, new drivers shouldn't be concerned with floating until they've mastered double-clutching.