Downhill Speed Control

[JimCal]

I have been driving a Motorhome for about nine years and have always been concerned about speed control in the mountains. I have always used the ROT that 'You go down in the same gear that you came up in.' However, sometimes the transmission is incapable of containing the vehicle's speed at a safe level using the selected gear. Further, I have always used a braking method whereby I regain the desired speed by braking fairly hard to reduce the speed quickly, then off the brakes until they are needed again.

Recently, I learned of a second procedure from my Cousin who is a long-time professional truck driver who has many, many miles under his belt in the mountains. He said there are two methods: the one I just related and one whereby a nominal pressure is applied to the brake (all the time, if needed) just to maintain the desired speed. He said that professional truck drivers use the second method.

I have never talked to another truck driver and have no way of knowing whether his story is accurate but my Cousin is not known to stretch the truth. However, I would like to hear from others, professional truck drivers especially, as to whether anyone has tried the second method.

Jim C.

[JimCal]

I have been driving a Motorhome for about nine years and have always been concerned about speed control in the mountains. I have always used the ROT that 'You go down in the same gear that you came up in.' However, sometimes the transmission is incapable of containing the vehicle's speed at a safe level using the selected gear. Further, I have always used a braking method whereby I regain the desired speed by braking fairly hard to reduce the speed quickly, then off the brakes until they are needed again.

Recently, I learned of a second procedure from my Cousin who is a long-time professional truck driver who has many, many miles under his belt in the mountains. He said there are two methods: the one I just related and one whereby a nominal pressure is applied to the brake (all the time, if needed) just to maintain the desired speed. He said that professional truck drivers use the second method.

I have never talked to another truck driver and have no way of knowing whether his story is accurate but my Cousin is not known to stretch the truth. However, I would like to hear from others, professional truck drivers especially, as to whether anyone has tried the second method.

Jim C.

[Tom N]

If you have an '05 or later Workhorse chassis you can use the "grade brake".

As to the going down in the same gear that you come up theory. If at the top of the hill you turn around and decend the same side you just came up there may be some validity to the theory.

If you don't there is no guarantee that both sides of the mountain have the same degree of curves, are the same grade and down hill distance.

[DonavonP]

It's my opinion that the 2nd method would lead to a brake fire/failure. I use your first method but I start down the mtn in 1st gear and if it seems too slow I'll up it to 2nd and apply the brakes if necessary to slow it down and then back into first if necessary.

2nd gear works ok for a 6% grade and 1st gear for 7% or higher. I'm always too slow for car drivers and just about correct for a fully loaded log trucks.

[DriVer]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by JimCal:
However, sometimes the transmission is incapable of containing the vehicle's speed at a safe level using the selected gear. </div></BLOCKQUOTE>Jim C., No need to worry about the Allison transmission. Select the lowest gear possible that will maintain a safe rate of descent and stay off the brakes.

In the event you need to use your brakes do not apply the brakes hard and scrub off speed in one continuous operation rather pump or jab your brakes in short intervals and you will scrub off speed and loose energy rather quickly. Once you've slowed down sufficiently downshift to the next lower gear and check you tach. If you're being held back too much and decelerating up-shift to the next higher gear and watch your speed.

[Full-Timers]

The old adage of going down the hill in the same gear as you went up is no longer valid due to the fact that we have more power to climb hills now-a-days. This means you can go up a hill in a much higher gear than you should go down.