Braking Downhill Question

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colleenfl

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Aug 7, 2006
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I am just getting ahead of myself and a lot of thinking about our 6000 mile trip out west next month (a year planning).  Being from FL and not having this discussion with my husband on this topic as of yet I thought I would ask here and surprise him when I bring it up. Here it goes...

This may sound dumb but can anyone give me any advise on anything special or that we need to know of breaking downhill or steep grades out west?

We are in a 40' DMH no toad, 2006 Fleetwood Discovery

I or we probably know what to do but does not hurt to ask.

Thank you
Colleen
 
You should have an exhaust brake, so use it on the downgrades.  Be sure to slow down BEFORE you start down the hill.  If the grade isn't more than 6% you should be able to descend with the EB on at about 45mph with minimal use of the service brakes.  If your speed increases, apply the service brakes fairly hard for 5-10 seconds to slow back down to your original speed, then let them cool.  The most important thing to remember is to not let the speed get too high while descending or you may not be able to slow it back down.  You'll find runaway truck ramps on many of the steeper downgrades out west and if your brakes do fail, head for one of those.  They contain soft sand and/or gravel that will stop you quite quickly.  Hopefully you'll never need to use one, but you should know they're there.

As you get experience driving in the mountains, you learn what gear you use to go up the various grades.  The rule is to use the same gear going down as you use to go up a given grade.  Speed likewise, if you go up a grade at 45mph, you should come down the grade at 45mph.
 
Thank you! Great information I have printed it out.
We do have an exhaust break. I have seen those runaway truck ramps and hope I never have to use one.

Thank you very mucy
Colleen
 
Colleen,

Exhaust brakes (sometimes called engine retarder brakes because they work against the engine exhaust) are wonderful.  We had a Pac Brake on our last motorhome and a Jake Brake on this one.  There's usually some kind of a rocker switch where you can switch it from high to low, giving you two different levels of braking power for different steepness of grades.  Used properly you sometimes can drive for hundreds of miles without ever using your service brakes.  When you approach a freeway exit, use the exhaust brake to slow down and you won't need the service brakes until you're almost at the stop sign or turn.  Ours "cuts out" at about 15 mph and you will feel it stop the retarding action when this happens.  Practice using the exhaust brake on easy slopes so you feel comfortable using it when you get to the real mountains.  Test how the high and low rocker switch makes it slow down on some grades but not others.

When you see special signs for truckers that tell them there's a brake check area, that's usually your clue to get ready for what is probably a long downhill.  Out here in the west some of our grades are 10 or 15 miles long, so it's important to save your service brakes for real emergency stops.  If the grade is over 5 percent or 6 percent, it will usually be on a sign that shows a truck going downhill.  If it says the truck speed is 50 mph, then my speed is 50 mph.  In other words, follow whatever directions the road builders provide to the truckers and you should be okay.  Some signs are quite unique.  For example, on I-80 going over the Sierra from Reno to Sacramento, we've always gotten a kick out of one of the signs that says "Let 'er drift" meaning there are no curves ahead so you don't need to worry so much about braking.  There also are huge "Slow Down" signs and they mean exactly that because there may be a bridge and curve at the bottom of the grade.  We have a few places on relatively short grades that are 20 mph zones, and it's usually a hill with a blind curve coming into a town or coming to a river crossing where there's an immediate turn on the other side.  Susanville CA is an example of the former and Mexican Hat UT is an example of the latter.  By the way, with regard to speed, we can keep it at slower speeds when we're not towing.  The added weight of your toad means you may need the exhaust brake more often.

When using your exhause brake, your brake lights on both the RV and toad probably also will go on.  It's nice to have someone behind you verify that they are coming on as they should.  Someone who has never driven an RV may think you're riding your brakes all the way down the hill, but the truckers behind you will know the difference.  If a truck is ahead of you and you see it's brake lights go on, the trucker probably knows the road and knows there's a curve coming for which he needs to slow down.  By the way, I tend also to follow whichever lanes the truckers are in while gong through metropolitan areas because they often know which lanes are problematic in heavy traffic.

Also on downhills, keep an eye on your RPMs when using the exhaust brake.  You don't want your RPMs to get too high.  We try to keep ours between 2000 to 2200 revs but this can vary by coach.  This is when you briefly apply the service brakes to further slow the coach as Ned mentioned previously.  In addition, there will be speed points on steep grades at which your exhaust brake needs supplementing with the service brakes.  Our current Jake Brake is at 35, 45, 55, 65 mph.  If I'm trying to stay at a truck speed limit of 50, then I try to keep my speed under that 45 mph point so I don't start speeding up.  If you let it go to 55, then you probably will have to use your service brakes to slow down and that's when they get hot.

Did you get your Mountain Directory Guide (East and West) yet?  You'll find they're quite useful because they tell you which roads are narrow, curvy, steep, etc.  There are maps for each state with a number for each one of the areas discussed.  They're great in that respect because you can pinpoint the route you want to take quickly.  They're worth every penny in my estimation.

Don't worry about the mountains.  They're beautiful and we love 'em!

ArdraF
 
I hope you never have to use a runaway ramp too.  They can get very expensive.  I used to work for a Chevron dealer that owned a couple of truck stops.  I heard from the truckers that, not only are the tow fees very expensive to get pulled out of one of these ramps, but some states fine you if you use one because they deem you let the vehicle get out of control.  Obviously, if it is a safety issue then by all means use the ramp as life is more important than money!
 
Thank you ArdraF

I have printed out everyone's post here for my husband (and of course I have read them I will be driving as well), he is not a real big on searching the internet plus it is good to have this written out to put into my book.

We have tested the retarder brakes but of course that was on flat land here in FL wo we know how it works and what it feels like etc. We may just leave the switch on for the trip I don't believe it will hurt anything to leave it on. I have heard that many people use it all the time for normal driving.

Thanks everyone
Colleen
 
You have been given some great tips and I am sure you will have no problem if you use them.  Remember no faster down than you went up and sometimes slower is in order.
 
Some people drive with the exhaust brake on all the time, it's a matter of personal choice.  One disadvantage is when you let off the throttle, the exhaust brake will engage and also turn off the cruise control, so if you're in flat land using cruise control, you will probably want to turn the EB off.
 
There is a song about a truck that is coming down a mountain and the drive shaft breaks.  So the driver pumps up the brakes (Bad idea) and sees them go in a white puff of smoke,  Now you know what the run-out lanes are for.  Try to avoid them

By the way, those lanes are loose gravel and will stop you,  FAST should you run into one  Loose to a serious depth in fact

Story of a runaway truck following a car down the mountain, finally the driver sees a run-out lane, idiot in car pulls into it, by by idiot, trucker had no choice but run him down (had the idiot stayed out of the truck run-out he'd have lived)

There are two schools on braking down hills.. I was trained the other way, but I'm not going to bore you with it as I truly think the method above is perhaps better and with my coach (A gasser with an allison tranny) is the recommended method.

Exhaust brakes may be prohibited in some areas (Watch for the signs)

Check your brakes often,  Keep them in good condition,  That is the most important advice I can give,  Engine don't work, Transmission don't work, You don't move but you are safe.  Brakes don't work and I hope you are not moving cause .... Well,,, Think of Mr. idiot in the story above and recall that when that coach runs into something you are going to know right away cause there is nothing between you and what you hit save a pane of glass, and it will be a PAIN!
 
Exhaust brakes are not prohibited, engine brakes are due to the noise they generate.  Exhaust brakes are silent.
 
Some people drive with the exhaust brake on all the time, it's a matter of personal choice.  One disadvantage is when you let off the throttle, the exhaust brake will engage and also turn off the cruise control, so if you're in flat land using cruise control, you will probably want to turn the EB off.

It depends on the type you have.  We have a floor pedal and the exhaust brake is not on until we press the pedal down.  When we take our foot off the pedal, the vehicle begins to speed up and eventually will work its way up through the gears, assuming you're still on a downhill.  I think engaging the exhaust brake and thereby turning off the cruise control is an advantage because you only have to take one action instead of two.  We've had both a rocker switch and a floor pedal and I LOVE the pedal.  Wouldn't ever want to go back to the rocker switch which sometimes took too much fumbling in a dicey situation.

ArdraF
 
Ardra,

You and Jerry were the ones who convinced us to go with the pedal for the PB. We have both the pedal and the rocker, but have rarely used the rocker switch since having the pedal installed. Much safer to use your idle foot than fiddling for a switch and, as you demonstrated to us, one has more control over when the brake comes on.
 
exhaust brake will engage and also turn off the cruise control,
remember to never use the cruise control  as you go downhill, and also never use it when it is raining...the bigger tires will run on top of water faster then car tires...the higher air pressure is the reason.and keep your brakes adjusted for a better stop..
hope this help....
 
What should I do with my 26 foot class C? It's on a Ford body and does not have anything but its regular breaks, any advice for going down the western mountains?
thanks,
Zach
 
Zach,

Yes, your gas engine unfortunately doesn't have anything like a Pac or Jake brake.  When going downhill, take it off cruise control and downshift as you start down.  If you can keep it in a low enough gear, it will hold you back and lessen your need to brake.  Not always, of course, but gearing down is very important.  As with the exhaust brake, don't let your RPMs get too high.  If it starts to "scream" then you need to brake some to reduce the RPMs.  Sometimes all you need to do is take it out of Drive which is really an overdrive and put it in third gear.  Other times when you need a really slow speed because of curves and low speed limits you may need to put it in second gear.  Generally first gear is too low and will make the RPMs go too high.

I believe they make something similar to an exhaust brake as a aftermarket item, but I don't know how effective they are.  Your best bet is to use your gears to best advantage.  Heck, I even gear down when driving the car to save the brakes in hilly areas.  I guess for someone who never learned to drive a stick shift, it's a new experience, but the effect is the same.  Downshifting slows the vehicle and means you don't have to use your brakes so much.

ArdraF

 
If your class c has a gas engine the gas engine provides good compression braking.  This is because Gas engines have a throttle valve that regulates how much air enters the engine depending on how much fuel is being provided.  I you have a diesel engine there is no real compression breaking because diesel engines do not have a throttle valve and the same amount of air is feed to each cylinder on each stroke and only the amount of fuel is varied for power/speed needed.  Therefore and exhaust break will provide the back pressure to achieve compression braking.

If you have a gas powered vehicle you drive normal using accelerator position and lower gears if necessary to control speed going down hill.   With a diesel either exhaust break or engine brake is needed to provide compression braking.

If you have a diesel I would suggest you look into getting a exhaust brake installed.
 
If you have the Allison transmission, it can be programmed for latch mode.  In this mode, when the EB switch is on, the brake doesn't activate until you press on the service brakes.  The EB then engages, and cruise control disengages.  When the ECM senses non-zero fuel flow again (you press on the accelerator) the EB releases and the cruise control reactivate.  Unfortunately, you have to pay to have the ECM reprogrammed.

Note: I know this works with Cat engines, not sure about Cummins.
 
That doesn't come close to the way the Pac brake works with a foot pedal and there's no need to pay to reprogram the ECM  ;)

The pedal cost $60 at Monaco parts' extortionate prices and it was installed free by Monaco techs at a rally. The best $60 we've spent on the coach.
 
The advantage of latch mode is you don't have to do anything to use the EB but step on the service brake pedal.  No pedal, no switching, just apply the service brake.  There is a 3rd party addon available that will do the same thing.  I believe Jim Godward has one on his DS. 
 
One advantage of the Pac brake pedal is that you don't need to step on the service brake pedal and contribute to premature wearing of the brake pads.
 

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