Driving downhill with a bigger rig. Suggestions please...

[stratus225]

I'm curious to know from some of the more seasoned RV'ers towing a trailer what suggestions you would have for the descent parts of the trip. I'm very new to this and just this morning already was in a stiuation just pulling the trailer home from the storage lot where a downhill slope got me thinking of how to handle it. I did start to apply the holy crap switch at one point as there were traffic lights at the bottom of the hill. That was bad enough, but I cant even imagine whats going to happen at 60 mile an hour on the highway. All suggestions, tipe and tricks are appreciated. Saftey first!

 

[John From Detroit]

I believe there are some "hints" in our library.. One rule is to use the same gear going down, you would use going up.. Problem is there are many hills where you go up a 3% slope and go down a 6% (or the other way around) and you don't know what is on the other side.. Till you get there.  (At least not the first time)

If you are worried,  DOWNSHIFT just before you get to the top of the hill 

Some vehicles have assorted "Slow down" options (IE: Mine) but not all do.

I've seen discussions on braking.. Two different schools..

But the #1 best thing you can do.. Beyond a doubt the #1 best thing you can do,  Is think about it BEFORE  it is too late

And by making the opening post in this thread.. You did just that.

 

[stratus225]

Thanx John. I checked the library out before I posted and could only find one line about travelling downhill and that was to downshift. I'll definately remember that and try it out tomorrow. I felt the trailer pushing on me today and remembered what alot of other people had told me which is to accelerate downhill to keep the trailer pulling rather than pushing. Good suggestion if there is no stop at the bottom of the hill, but then again it would pretty easy to be reaching speeds of 70+ mph pretty quickly which I'm not sure if I'm comfortable with yet. I'm so looking forward to the day when I can look back and realize that I worried alot for nothing alot of the time, but for now, I'm good with worrying and asking questions. 

 

[Carl L]

In handling long downgrades use your gears and the engine brake in preference to your wheel brakes.   There is a rule of thumb that you go down a hill in the same gear you used to come up it.  That rule works fine if the grades are the same.   If not favor a lower gear until you can establish what gear you need.   Start out by locking out your overdrive, if any.

To shift down, apply your brakes to slow the rig, then down shift and release the brakes slowly to allow your engine rpms to rise and the engine brake to take effect, then coast.   If you find yourself still gaining speed to rapidly, downshift again.   There is no dishonor in going down a hill in first gear -- nor for that matter up the hill in first.   Look at the big rigs, whose company you will be sharing.  They are going slow too.    

You will touch your wheel brakes to trim the speed.  If you find yourself constantly using them, that is a signal to downshift your transmission.

If you have a tachometer in your truck learn to use it in gauging your proper speed and avoiding lugging your engine in too high a gear.

If you have a diesel, get a engine braking device installed if it does not have one already.

One last thing.  If you are pulling a trailer, check out the operation of your trailer brakes before you enter the downgrade, preferably when you can still stop and correct failure to operate.  You may note that there is a brake check area for trucks just before a big downgrade.  Take a hint and you use it too:  roll in at 15-20 mph and apply the trailer brakes.  If you cannot feel them, stop and correct the problem -- 9 times out of 10 it is the bloody trailer connector with a dirty, corroded, or bent brake circuit prong/socket.

 

[Ned]

The secret to descending safely is go slowly, slower than you might otherwise go without a trailer in tow.  If you are towing with a diesel, use the exhaust or engine brake.  If your diesel tow vehicle doesn't have one, it should.  If it's gas, downshift and keep the speed under control.  With either gas or diesel, you don't want to let the speed to increase to where the transmission upshifts.  Use intermittent applications of the service brakes to keep the speed under control.  A series of hard applications with time to cool off in between is best.  Don't ride the brakes or they'll fail just when you need them.

 

[ArdraF]

Carl mentioned being in the same company as trucks, so the other hint is to do what the truckers do.  When you see signs telling the truckers that there is a 6 percent downgrade for 7 miles, then do what they do which is downshift at the top of the hill before gaining speed.  If the road has curves and the signs say trucks 30 mph then you should also stay at or below 30 mph.  You also should know that in many states RVs are classed in the same speed categories as trucks, for example California where both trucks and RVs have a maximum speed limit of 55 mph.

ArdraF

 

[stratus225]

I just have to say, you guys rock! Thank-you very much for the constructive advice rather than the usual comments of "why are you posting here?" or "check former posts and you'll find what your looking for". Thanx again guys, this advice is invaluable to a newb!

Dave

 

[Ray D]

remembered what alot of other people had told me which is to accelerate downhill to keep the trailer pulling rather than pushing.

From an old trucker, don't do that. I don't know who  the people are who told you to do that, but I doubt they do much towing on steep grades. They wouldn't be around to suggest that, if they had tried it. Don't try to "outrun" your trailer, down-hill!!!  

Really good advice from others, above.

Ray D

 

[Jim Godward]

I haven't towed in many years but if your trailer has a controller to adjust brake gain, you can set it to apply just a ittle braking more than the MH and thus keep the trailer behind you.  CAUTION, this can be hard on your trailer brakes so you have to be very careful if you do this.  We only did this on long curvy STEEP roads this though.

If you do this it is very important to be sure to reset when you are off the hill and to use you MH brakes as previously indicated.  I know of only 2 places on the interstates in MT, a couple in ID, etc., where I would consider using this technique and only with heavy trailers.

If you have proportional braking on the trailer, you should be OK on all grades.

 

[Carl L]

I felt the trailer pushing on me today and remembered what alot of other people had told me which is to accelerate downhill to keep the trailer pulling rather than pushing. Good suggestion if there is no stop at the bottom of the hill, but then again it would pretty easy to be reaching speeds of 70+ mph pretty quickly which I'm not sure if I'm comfortable with yet.

For some reason, I just noticed this!  Ray D. is spot on!  The very last thing you want to do with a trailer is to accelerate going downhill on a long grade.  That ain't a tactic, that is a suicide pact.  You want to take it slow, gravity is going to do all the accelerating you can handle.  If you feel the trailer is pushing on your truck when you are braking with the wheel brakes it may be a sign that you need to up the gain of your trailer brake controller -- read the controller's manual thoroughly and follow its advice. 

 

[jerryarlyne]

Most of the above advise is right on. But the question should be knowing when to downshift and how not to over use the service brakes.

The answer is, apply the brakes and slow down, then remove your foot completely from the brake pedal for at least 5 seconds before having to reapply.

If you find yourself having to apply the brakes more often then that, then you are in the wrong gear and will need to slow down and downshift to the next lower gear. Even if that means going all the way to first gear.

 

[Gary RV_Wizard]

If you don't know what's on the other side, or if you know the downhill is steep, cross the crest  of the hill at +about 10 mph and start down at this very low speed.    You only have to back off the throttle for the last 50-100 feet of uphill to slow way down, so you won't be holding up traffic to do this. Then downshift to a very low gear. You can always upshift if you don't need as much retarding force and upshift is easy, whereas downshfting once you are going too fast is hard (requires heavy braking) or impossible.