Like many firefighters, I donate my time as a professional volunteer. Having just gotten back from a college field studies trip to Death Valley, something came up that ended up with more opinions than answers. So, it’s FFN time to see what others know about the subject and hopefully in the process this post can elicit some good discussion and guidelines for steep grade downhill driving.



When you are driving a truck, or in this case a bus filled with students, and you encounter a 9% grade, has it ever occurred to you that you could loose your brakes? It happened to us a couple of days ago and by the grace of God, no one was hurt and the bus could be limped into our base camp without incident. 


The driver maintained constant brake pressure and eventually the brakes started to smoke, to the point where it looked like there was an engine fire. The bus driver applied brake pressure but the pedal went to the floor and the bus was picking up more speed. The only thing that ended up stopping the bus was a soft gravel section of roadway on the opposite side of the road. The gravel stopped the bus.


The discussion point questions are as follows:


  1. When driving downhill, especially on a steep grade, do you “fan” the brakes, as in 10-seconds on and 10-seconds off?
  2. Do you continuously apply 10-pounds of pressure on the brakes, all the way down the grade?
  3. Do you keep the same gear, as you would use going uphill for downhill driving?
  4. What have you pre-planned if you totally loose your brakes?
  5. Can you depend on the Emergency Brake if your foot brake does not do the job?
  6. Do you have any advice for new drivers encountering this situation?
  7. When you come to a complete stop after an overheated brake incident, do you mark the tire and roll the vehicle back 180 degrees to move the hottest
    part of the brake drum to the top to enhance cooling?
  8. Has this ever happened to you?
This has happened to firefighters that also have other issues to contend with such as stored tank water and a high center of gravity...

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I've found that stab braking method works best for me. I've drove tractor trailers nationwide for 5 and a half years and this always works best along with gearing down and using a retarder if so equipped. If not equipped select one gear lower than the gear that you would think that you would need. Never ride your brakes they will burn up as you found out the hard way.
I use the "fan" method you describes, but when in a manual transmission, also downshift.
Can someone explain point 7 in Mike' post about cooling. never heard of that. In fatc ithought the drum, like pads, are in a fixed position and can't be rotated. Or am I misunderstanding the post????
This kind of hill and tough turn section are the reason "jake brakes "were made instead of beating your brake system up let the engine back you down and then use brakes..you do it right and you will come out of the situation as if it were normal driving conditions..sadly most people use these "jakebrakes" daily for normal conditions and they can do more wear and tear than good..normal road ways you should drive the truck not let it drive you and use a system to get control back at a light or stop sign
One thing that has not been mentioned is how to deal with failure in air brake systems. If Air pressure is being lost, do not stab, fan, or pump the brake pedal as described. This will cause rapid loss of pressure and control over the brakes will be lost. At 0 PSI the rear brake cansiters will apply the Parking Brake and possibly lock the wheels causing skid. Instead, once the pedal is applied it should be held in position until a safe stopping location is found. Then the braking system and any remaining air can be used to stop the vehicle.
This is how I was taught, has anyone learned different either from experience or classes?
A lot of steep grades have escape ramps built in . These roads are deeply topped with gravel meant to stop your vehicle much as CBz bus stopped in gravel . As in most situations pre plans are important, gear down in advance and slow and easy will get you there, as most of these posts advise.
In my opinion, you should fan the brakes and grab the lowest forward moving gear you can if possible, that way your transmission helps slow you down taking some pressure off the brakes.

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