Using the engine brake?

[Wannabe]

I understand that the engine brake would normally be used for going down long grades, but is it OK to use it to aid in sudden or normal stops for lights, traffic, etc.? It seems to force the transmission to gear down quicker than normal. Any chance of damaging something? Thanks!

[bluepill]

Go to the Allison website. You can download the operator's manual in pdf format.

[ottffss]

Quote:

Originally Posted by Wannabe ...to aid in sudden ...

In a sudden stop the stop will be long over before the engine brake engages.

[LVJ58]

Quote:

Originally Posted by Wannabe I understand that the engine brake would normally be used for going down long grades, but is it OK to use it to aid in sudden or normal stops for lights, traffic, etc.? It seems to force the transmission to gear down quicker than normal. Any chance of damaging something? Thanks!

Oooops I didn't notice you have a DP, ours is a gas rig, so I'm deleting my post.

Safe Travels,,

[RickO]

Assuming you don't mean a "panic stop"... I think it's fine and do it all the time.

Rick

[BobGed]

Does no harm at all to have it engaged all the time. Even though it pre-selects 2nd gear, the transmission will only downshift to the next lowest gear when safe to do so. It will have a slight affect on your fuel mileage.

[Wannabe]

Quote:

Originally Posted by ottffss In a sudden stop the stop will be long over before the engine brake engages.

I should have left the word "sudden" off-I probably couldn't even find the engine brake in a "sudden" stop.
PS: I have read the Allison manual, but don't remember any reference to low speed, in town, use-maybe I missed it.
Good to hear that it's OK to use it!

[Steve Ownby]

Turn it on and learn by doing. It's not possible to harm the drive train by leaving the brake on. The main caveat is, turn it off in conditions of slick road surfaces.

If you have a single off/on switch then you have an exhaust brake, which is external to the engine and works by increasing exhaust back pressure. If you have an off/on switch and a high/low switch then you have an engine compression brake which is internal to the engine and effectively turns the engine into a big air compressor.

Safe travels.

[ahicks]

Quote:

Originally Posted by Wannabe I understand that the engine brake would normally be used for going down long grades, but is it OK to use it to aid in sudden or normal stops for lights, traffic, etc.? It seems to force the transmission to gear down quicker than normal. Any chance of damaging something? Thanks!

I turn mine off in heavy local traffic. Don't like the harsh shifting. Otherwise it's on. It IS something to get used to.

We've spent the last 4 weeks traveling in Virginia, West Virginia, Maryland, PA, and Ohio. This has been not only very scenic but quite the education regarding driving in the hills! Up the hills pretty simple. At wide open the trans does a pretty good job of keeping the engine in it's power band. Down hills, not so simple!

The trick is figuring out what gear you need to maintain a speed that won't increase too much as you descend. In ours, a 6% grade in 6th gear is going to get interesting quickly. That same grade in 5th not too difficult with occasionial brake usage - but to get into 5th at over 65mph or so you have to slow down to something under 65 to let it shift! Not cool at all when you realize this as your speed is climbing quickly and approaches 75 mph with the tranny thumbing it's nose at you trying to keep the engine in one piece! It's not going to let you downshift if doing that might hurt it! Hill or no hill....

If I've learned one thing, it's that different grades require different gears, which require different entry speeds. Figure that out and your home free!

[docj]

I have a compression brake (a Jake) that puts the Allison in 4th gear. I engage it on the interstates in heavy traffic and anytime I am driving on city streets. When going from traffic light to traffic light having the Jake on means significantly less use of the brake pedal and I find it an easier way to drive.

As for coming down mountains, we just finished several months in "real mountains" in MT, WY and ID and having the Jake and downshifting the Allison takes a lot of stress out of the drive.

[Pusherman]

The Allison transmission will never let the coach shift down to a lower gear and do any harm to the transmission or engine. It's a very smart system.

Also, you can have the gear selection re-programmed to a higher gear, like 4th gear instead of 2nd gear, when the engine/exhaust brake comes on. I had mine changed from 2nd gear to 4th gear and really like the drivability (and braking) with the exhaust brake reprogrammed this way. As others have stated, downshifting to 2nd gear is way too agressive for me. If you need to further downshift with the engine/exhaust brake, you can use your shift pad to downshift further.

With this reprogramming, I use my exhaust brake all the time.

An Allison dealer can do the reprogramming.

[Midniteoyl]

Dont forget, some municipalities dont allow the use of an engine brake..

[Mr_D]

Quote:

Originally Posted by Midniteoyl Dont forget, some municipalities don,t allow the use of an engine brake..

Usually it's for UNMUFFLED exhaust brakes, not the ones used on MH's.

[Mr_D]

Quote:

Originally Posted by Pusherman The Allison transmission will never let the coach shift down to a lower gear and do any harm to the transmission or engine. It's a very smart system. Also, you can have the gear selection re-programmed to a higher gear, like 4th gear instead of 2nd gear, when the engine/exhaust brake comes on. I had mine changed from 2nd gear to 4th gear and really like the drivability (and braking) with the exhaust brake reprogrammed this way. As others have stated, downshifting to 2nd gear is way too agressive for me. If you need to further downshift with the engine/exhaust brake, you can use your shift pad to downshift further. With this reprogramming, I use my exhaust brake all the time. An Allison dealer can do the reprogramming.

I had that done, forever after wished (till we traded the rig that is) I had left it preselecting 2nd.