Exhaust Brake ???
The other day coming over Donner Pass, going down hill, I let my speed build up to about 65mph, I switched on the exhaust brake and nothing happened, I let it go for awhile, and nothing, I finall...
Forum Discussion
When you say "nothing happened", please be more specific:
Did the Allison shift pad go from "6" to your pre-select gear for the exhaust brake (normally 2nd or 4th, but can be anything)?
Did the transmission downshift (probably from 6th to 5th)? The 6-5 downshift should have occurred immediately, assuming that 5th gear at 65 would not overspeed the engine. If that 6-5 downshift would have overspeed the engine in 5th, it should have turned on the exhaust brake, but not downshifted until slowed enough that it would not overspeed the engine.
And BEST PRACTICE on a long downgrade is to find the combination of gear and exhaust brake that keeps you speed in EQUILIBRIUM. That is you are neither speed up nor slowing down without use of the brake pedal/service brakes. As a practical matter pure physics dictates that this speed is faster than a loaded 18 wheeler and slower than an empty one. If you are faster than all the trucks, YOU ARE GOING TOO FAST.
Did the Allison shift pad go from "6" to your pre-select gear for the exhaust brake (normally 2nd or 4th, but can be anything)?
Did the transmission downshift (probably from 6th to 5th)? The 6-5 downshift should have occurred immediately, assuming that 5th gear at 65 would not overspeed the engine. If that 6-5 downshift would have overspeed the engine in 5th, it should have turned on the exhaust brake, but not downshifted until slowed enough that it would not overspeed the engine.
And BEST PRACTICE on a long downgrade is to find the combination of gear and exhaust brake that keeps you speed in EQUILIBRIUM. That is you are neither speed up nor slowing down without use of the brake pedal/service brakes. As a practical matter pure physics dictates that this speed is faster than a loaded 18 wheeler and slower than an empty one. If you are faster than all the trucks, YOU ARE GOING TOO FAST.
