Retarder Settings/Allison Transmission

[BrianE]

Jim is absolutely right. When returning from Florida recently, I downshifted on a grade and momentarily saw 2500RPM. Be very careful when downshifting for compression assisted slowing.

[Jon Wehrenberg]

I think if the shifting is left to the computers, such as letting the bus downshift by itself according to how it is programmed the bus will not over rev. It also will not give you the maximum performance because to be most effective with a jake for example the higher the revs the better it works.

When we were out west this spring I was manually managing the coach shifts to maximize the effectiveness of the retarder while controlling heat and to do that you must know the rev limits per each gear. On my coach for example fourth gear tops at 55 MPH at 2100 rpm. Unless I was below 55 I could not and would not select 4th. I never exceeded the 5th gear rev limits so I could always hit fifth at any time going up or down hills.

[rfoster]

Having owned a Prevost with the more exspensive retarder, and now a Prevost with a two stage Jake brake- I have made the following conclusion.

I'll take the Jake its cheaper and I prefer it.

I had the opportunity yesterday to descend Fancy Gap and I 77 South in North Carolina and never had to touch the brakes and no concerns with Temps either engine or tranny. I consider this a significant plus for whatever it is worth.

Now having said that to everyone that is shopping for their first Prevost, I would not let the retarder or Jake be a deal breaker, but if all else is equal when considering between more than one coach, I would take the Jake.

[jelmore]

We spent a lot of last year in the Rockies with a retarder. Steep grades are scary and it takes a lot of retarder, manual gear shifts and brakes to keep things under control. Overuse of the retarder unexpectedly and quickly got the temperature up to the alarm point of 330°. Slowing early seems the best defense. I had Allison check the transmission codes and there was no history of overheating, and from what I have read that over temperature alarm is from the retarder sump and not the transmission. Still, being in the mountains is a thrill. I don't know what is involved in a brake job, but the last check showed we have many, many miles left. Thank goodness. Since I can't do the brakes myself, I would presume that it is very expensive.

Anyone know what the expected life of brakes are?

[Jon Wehrenberg]

The environment you drive in dictates the life of brakes. I have 214,000 and my drives and tag are original, the front was replaced at about 165,000. I replaced all firction material on my first coach at around 200,000. Not worn out, but cracks in the lining on a couple of shoes.

Also, if you tailgate or rely on brakes while going down a hill you will get less, and if you are easy on the brakes you should get more.