2017 Fleetwood Discovery Brakes

[barmcd]

I'm thinking it's not actually a transmission retarder. I've driven a 450 hp Foretravel with transmission retarder and that thing would slow you down. It had a lever to adjust the amount of braking action and in the full forward it felt like you were hitting the brakes hard.

[Mr_D]

Originally Posted by alank

The Discovery has a transmission retarder controlled by a switch just behind the transmission gear selector. With your foot off the gas and just a little brake use, it should be downshifting the transmission. If you don’t have a good enough feel to identify downshifting, look at the gear numbers to see if it is working. You don’t have an engine brake per say.

The only production motorhome that uses a transmission retarded is Foretravel. They use a small joystick to control the braking force. If you have a single position switch then you have a exhaust brake which, on later models, also uses the variable vane turbo to help.
My ISX has a three stage engine brake. I have yet to find a downgrade that needed the high setting to hold my speed.

[Leibercoach]

Is there any aftermarket device that can be applied?

Previous motorhomes we had were 2005 GulfStream and a 2010 Discovery both which had much better stopping power.

ISL 8.9 pulling
Towing Tige ASR, Cimmarron 4 horse trailer.

[FIRE UP]

Originally Posted by Leibercoach

Is there any aftermarket device that can be applied?

Previous motorhomes we had were 2005 GulfStream and a 2010 Discovery both which had much better stopping power.

ISL 8.9 pulling
Towing Tige ASR, Cimmarron 4 horse trailer.

Leibercoach,
Well, yes, there is aftermarket braking systems that are phenomenally effective. But, they are also PHENOMENALLY expensive! One in particular is called the "Telma Retarder". We had them on just about all of our fire trucks. In short, it fits on the drive shaft, primarily attached to the differential. It looks just like a very large and complicated double DISC BRAKE. But, in fact, there are NO CONTACT COMPONENTS! In other words, NOTHING touches when the unit is activated.

How it works is primarily magnetic activation. Almost the same as a "Mag-lev" train. Except Mag lev trains work opposite of this unit. In our units, we had two, 16" diameter discs. But, in between those two discs were 8, very large and seriously powerful coils. The coil ends sat right at, 1/16th of an inch, away from the inner surfaces of those discs. Those coils were about 3" in diameter. We had/have a control "Joy stick" with (4) detents, at our control, right next to the steering.

When you pushed that small, four inch long joy stick forward, you'd move it one detent. The Telma was now activated but, at minimal braking. You could feel it but it was definitely minimal. Push it to detent II, and, you'd start to feel that rig slow down pretty good, based on the speed at which you were at , at the time. Push it to the III position and, you were really slowing down good. Push it to IV and, it would about lock you against the seat belt. But, the one nice thing about those Telmas was the fact that they were inter-wired with the ABS system. If the ABS system was even remotely activated, the Telma was instantaneously disconnected. No need to worry about not using it during rainy conditions.

And this is WITHOUT the additional use of the Jake brake AND THE service brakes. If you used both the Telma and the Jake brake, better grab ahold of something 'cause you were STOPPING RIGHT NOW. And your service brakes weren't even WARM.

Now, the primary need for the application of the Telma was a VERY LARGE BATTERY BANK. We had 6 Optimas on all our trucks. So, needless to say, we had battery power. But, we also had 450 amp alternators on all our trucks. But, anyway, yes, there are aftermarket braking devises available.
Scott

https://www.telmausa.com/benefits/retarder-comparisons

[NevadaNick]

Ask your local Cummins dlr about converting to actual engine brake instead of exhaust brake. It can be done.