steep hills and no jake break??

[bevans6]

I've been down that I-40 hill in my pickup towing my race trailer, and it is a doozy.  I passed a mobile home trailer, on eof the ones with a dozen sets of wheels under it, and the smoke coming out was interesting to say the least - it was doing about 15 mph.  In my bus with no jakes I'd be in second gear, up or down.  In my truck I was in third gear.

I was trained to use BW's methodology, and do use it.  My trip through Quebec and New Brunswick from Rivier Du Loop has many grades up to 9% or so, long ones, and I never had a problem with third gear or fourth gear and snub braking.  I find that if a road is designed for 70 mph, I can roll down it at 70 not overspeeding in fourth and snub braking as required with no (in my case, simply mis-adjusted and not working) jake brakes.  It's the roads that are designed for 50 mph that are interesting and challenging.

Brian

[robertglines1]

Observation: on Andy's Toter home was told previous owner overspeed engine going down grade in west and twisted shaft off in injector pump. Cummins powered. FWIW.

[robertglines1]

Never had to deal with steep grades of the west: So I have been reading and learning. Thanks for that. It makes sense to me. I will be the slow poke going down the steep grades. I understand the Jake principles but other than knowing my bus has them --that is where it ends. Learning something new every day.     I'm retired and in no hurry!    Bob

[BRUISER]

Never had to deal with steep grades of the west: So I have been reading and learning. Thanks for that. It makes sense to me. I will be the slow poke going down the steep grades. I understand the Jake principles but other than knowing my bus has them --that is where it ends. Learning something new every day.     I'm retired and in no hurry!    Bob

heck, I am young and in no hurry

[artvonne]

I guess the one thing I did not see answered unless I missed it.. is if I am in 2nd gear will the tranny only let the bus go so fast.. or will I still need to use the brakes a few times to slow it down, and if I was t onot use the brakes but let the tranny do all the work am I causing long term issues with tranny by doing this?

  If the gear your in is too high for the grade your decending, the engine cannot hold it back and youll pick up speed where youll have to use brake. The engine governor only keeps the engine from over revving while under power, there is nothing on Gods green earth to stop it from over revving if its being driven by the transmission through momentum. If your in any gear, and you get it above the next lower gears redline speed, and you cant slow it down because the brakes are gone, you can no longer downshift to the lower gear because you cant rev the engine high enough to get it in. And Auto's wont down shift to a lower gear once their going a certain speed either. Personally, if it was running away in second or third and I couldnt slow it down with the brakes, id keep it in that gear and let it unravel and pray it didnt blow. And once it nears governor redline speed, if you put in the clutch and shift out of gear, youll never get it back into that gear either. And if the gear you were in wasnt holding it back, the next ones going to be like neutral and your going to be in real trouble. At least if the engine explodes it will lock up (hopefully), and youll have one last chance of stopping it.

  If it comes out of gear and your brakes are gone, they better look out below, or you better pray you find one of those run away truck ramps. Man those look scarey. I would hate to ever be in a position where I was hoping to find one. Best to just get into that lower gear before you go over the hump.

  "I looked at Earl and his eyes was wide, his lip was curled, and his leg was fried. And his hand was froze to the wheel like a tongue to a sled in the middle of a blizzard. I says, "Earl, I'm not the type to complain; but the time has come for me to explain that if you don't apply some brake real soon, they're gonna have to pick us up with a stick and a spoon."

  I think thats what Dad used to say, "brakes are for stopping, not for holding speed on a grade".

 

[Lin]

I have an auto with 2-stage Jakes, and they certainly make life easier.  However, we did go down the same grades before with the Jakeless Spicer.  You just go slow in a low gear.  If you are in third and starting to pickup speed faster than you should, don't wait until the gear tops off.  Brake and bring it down to second.  You could just start one gear lower than you think will be right.  If the bus maintains speed, or almost does, without braking, your in the right place.  If the bus is slowing down, you can consider the next gear.  Knowing what is in front of you also makes a difference.  If you see that you have a clear, straight run at the end of the grade with no traffic in the way, you can consider up shifting and picking up some speed.  If there are curves, just crawl along.

[Len Silva]

[Lin]

Oh yeah, as you crawl along at 15-20 mph, you might feel like you have time to get up and make a sandwich, but don't do it.

[Seayfam]

About 22 years ago when I got my CDL, the one question I missed, I will never forget. The test said that going down a long 6% grade you should apply light even brake application. I got that question wrong. (My answer was to snub the brakes) All these years of driving, I have been using this method. So after this thread started I did some research, this research conformed "BW's theory" here is the article.

           Downhill Braking

 
Snub don't ride!

•Some drivers don't understand the severe demands put on the brakes by long downhill runs. Suppose your doing 6 miles with an average 6% downgrade. Runs like this are common out west. (In the east too?) This is a 1900' change in elevation. A free fall from 1900' results in a terminal velocity of 238 mph- neglecting air resistance. This would be the velocity of your rig -neglecting air and rolling resistance- if you didn't brake.
 
•Negotiating this grade is the same as slowing down from 238 mph. This is like 16 stops from 60 mph (not 4, kinetic energy varies with the square of the speed: (238 x 238) / (60 x 60) = 15.74 ) Suppose you average 30 mph coming down, the run will then last for 12 minutes. Sixteen stops from 60 mph in 12 minutes is a lot of stopping. Obviously your brakes had better be right and you had better use the right braking technique if you want to make it safely to the bottom.
 
•In recent years there has been some erroneous information going around about how to brake on long downhills. It was suggested not too long ago that a continuous application of the brakes as opposed to intermittent application or snubbing was the preferred method. THIS IDEA IS COMPLETELY WRONG!
 
 •The proponents of the old theory have rescinded it, there is now (almost) universal agreement that the proper way to brake on a downgrade is to intermittently apply all your service brakes in a way that will reduce the speed of a fully loaded vehicle by about 5 or 6 mph during each application. What is key here is not the speed drop, this will depend on weight, grade and other factors, but air pressure, you have got to get the application pressure high enough to get all your brakes working.
 
 •In theory, it doesn't make any difference whether you ride or snub the brakes on the way down. The problem is that you don't drive a theory, you drive a truck. In theory, the same amount of heat is put into the braking system regardless of how you apply the brakes. In practice, unless your brakes are in good condition, tractor-trailer balance is right and the load is ideally located, the continuous application of the brakes is likely to result in uneven drum and lining temperatures and problems before you get to the bottom of the hill.
 
•Steady, low pressure application of the brakes may not cause all the brakes on the vehicle to apply and may result in some brakes -those with the lower activation pressures- doing more work than others. Specifically, in many cases the tractor brakes will do too much of the work while the trailer brakes loaf and you might then get fade at the tractor axles.. Other brake problems can be aggravated by the low and steady braking technique. What you want is all the brakes working some of the time, not some of the brakes working all the time. The application pressure must be high enough to ensure that all brake chambers apply and that all linings make solid contact with the drums - about 20 psi or higher.

I may get pounded for this statement? But I think all of us bus owner's that don't have CDL's  should at the least have an air brake endorsement!

[Len Silva]

Do you think the same theories would apply to:

1. Disk Brakes?

2. Anti-lock brakes?

[robertglines1]

Len ; good ? I have them on 98.   Bob

[Seayfam]

Do you think the same theories would apply to:

1. Disk Brakes?

2. Anti-lock brakes?

As far as my researches go, yes I do.

Here is the the proper tecnique according to the Commercial drivers manual here in Alaska.

5.4.6 – Proper Braking Technique
Remember. The use of brakes on a long and/or steep downgrade is only a supplement to the braking effect of the engine. Once the vehicle is in the proper low gear, the following is the proper braking technique:
• Apply the brakes just hard enough to feel a definite slowdown.
• When your speed has been reduced to approximately five mph below your "safe" speed, release the brakes. (This application should last for about three seconds.)
• When your speed has increased to your "safe" speed, repeat steps 1 and 2.
For example, if your "safe" speed is 40 mph, you would not apply the brakes until your speed reaches 40 mph. You now apply the brakes hard enough to gradually reduce your speed to 35 mph and then release the brakes. Repeat this as often as necessary until you have reached the end of the downgrade.

[RJ]

Do you think the same theories would apply to:

1. Disk Brakes?

2. Anti-lock brakes?

Len -

Yes and yes.

However. . .

Disc brakes can tolerate far more heat than drum brakes, simply because so much of the disc is exposed to cooling air.  I've often seen discs that were "cherry red" from heat on race cars that were still functioning.  But if the PADS are of the wrong material, the discs can fade just as badly as drum brakes, altho it will be further down the mountain when it happens.  The pad material used on HD equipment like our buses and trucks is designed for high temperature operation, so it will take a LOT to get 'em really hot enough to fade.  But you can still do it by using stupidity.

Anti-lock brakes are affected by heat just the same.  They're designed to release the brake to allow the wheel to start rolling again when it starts to slide (the old "pump the brake" idea, but so much faster than a person is physically capable of.)  If/when the discs/drums/shoes/pads get hot enough for fade to set in, the wheel will keep right on rolling, not sliding like on ice.  At this point, anti-locks are useless - look for the runaway truck ramp.

One big difference between the grades in/around the Appalachians and those in/around the Rockies and Sierras are the lengths of the grades.  A couple of examples:

I-5 NB from Los Angeles over the Grapevine.  Summit is 4144 feet - once you crest it and start down, you've got about three miles of 4%, then it changes to a little over six miles of 6%.  Trucks are restricted to 35 mph, and there are at least three runaway truck ramps - often used.

I-80 WB from Reno, NV to Sacratomato, CA.  When you crest Donner Summit (7229 feet), you'll now be faced with 70 miles (yes, you read that correctly, miles) of 4, 5 and 6% grades until just east of Rocklin.  Brake killer.  But CalTrans has intelligently (is that an oxymoron?) posted yellow warning signs for the trucking industry advising safe speeds for decent.  There are some runaway ramps, but they are not utilized nearly as much as those on the Grapevine.

Back when I was in the charter bus industry, the majority of the fleet had jakes, with the exception of the two 4106s and two of the older Buffaloes (the newer 4905s had them).  All the MCIs, Eagles and Prevosts had automataics with jakes.  After I became familiar with the road, it was easy to hold a steady 65 mph in 4th with the Jake coaches all the way down, never having to touch the service brakes, except for traffic. (Nice to have cool brakes!!)  The non-Jake coaches were kept in 3rd with little to light braking as needed (more braking was needed with the 40-footers).

Let me put it this way:  Going downhill means you have to DRIVE the coach!

FWIW & HTH. . .

[GilligCrown]

Never having driven a bus before, I bought my Gillig Cummins/Allison with 3-stage Jakes in Arizona. I stayed overnight in Golden Valley (between Kingman and Bullhead), and used the high-idle switch to aid in airing and warming up in the morning. While descending the long, steep grade into Bullhead & Laughlin (93?) I knowingly and confidently threw the Jakes switch, with no effect whatsoever!  I was only going about 45mph, but it did spike my adrenalin. About the same time a few gentle applications of the brakes convinced me it could be stopped, I realized the high idle switch was left on, thereby defeating the Jakes. The rest of the descent consisted of a pleasant, reassuring rumble  .   

[trucktramp]

I have been over many passes at close to 80,000 lbs usually without any jake brake.  If you use your head everything will be fine.  Read the signs and keep your speed accordingly.  Those speed limits were set for a reason.  I have always used the snub method and only had problems once.  I crested the hill and did not downshift.  Half way down I was somewhere north of 80 mph and had no brakes from trying to ride them and then snub them after they started to get hot.  I made it to the bottom in one piece but had to change my underwear at the bottom.  Talk about maximum pucker factor.  Needless to say, I never made that stupid mistake again.