Auxiliary brakes

[Jandcinok]

Yes, Im new here, we dont have a motorhome yet but Im here doing lots of reading and learning.

I see folks talking about jake brakes, exhaust brakes, and occasionally I see a reference to retarders.

Now, heres the question, do they put driveline retarders in motorhomes?

[Gary RVRoamer]

Yes, but I'm not aware of any aftermarket add-on retarders nowadays (there used to be a couple). Allison Transmission has a retarder option for their bigger models, and many of the larger Cummins diesels have a built-in "Jake" engine brake. There are add-on exhaust brakes for about any other diesel. I think Foretravel coaches have the driveline retarder, but most other diesel pushers use an engine or ehaust brake. They are standard equipment on most DP models these days.


Gas engines have inherent engine braking, so there isn't much market for brake add-ons for gas engine coaches. Probably why the previous products are no longer offered.

[LDMcL]

Originally Posted by Gary RVRoamer

Yes, but I'm not aware of any aftermarket add-on retarders nowadays (there used to be a couple).....

Gary:

A little bit of trivia for your information.

Back in the day, Blue Bird had an option to install an electric driveline retarder on its front engine Wanderlodges.

It was built by Telma and, from its web page is still in business.


https://www.telmausa.com/

[Ray,IN]

Originally Posted by LDMcL

Gary:

A little bit of trivia for your information.

Back in the day, Blue Bird had an option to install an electric driveline retarder on its front engine Wanderlodges.

It was built by Telma and, from its web page is still in business.


https://www.telmausa.com/

KLAM Magnetic Retarder system appears to still be in business too.

Driveshaft retarders were the most effective speed reduction device made, IMO the reason they are no longer used is initial price+installation was cost-prohibitive(4 to 8 thousand dollars today).
Jacobs patented their driveline retarder in 1997, which is now abandoned. I think theirs was more expensive.

[FIRE UP]

Originally Posted by Jandcinok

Yes, Im new here, we dont have a motorhome yet but Im here doing lots of reading and learning.

I see folks talking about jake brakes, exhaust brakes, and occasionally I see a reference to retarders.

Now, heres the question, do they put driveline retarders in motorhomes?

Jand,
If you're not familiar with all those terms. I'll give you the short version.

1. Exhaust brake
A. A system by which a blade valve, closes off the exhaust system to create back pressure which, since the engine cannot get rid of it's back pressure, it is now acting as a form of a braking devise. Not a bad system. It' s usually on all the smaller diesels. It is not adjustable. It's ON, or it's OFF. It is normally tied in with the transmission so, as the E-brake, as it's commonly referred to, is applied, the transmission, in accordance with descending speed, will auto-down shift to a given point and speed.

2. Jake Brake
A. The technical name is a "Compression Brake". This system utilized engine internal parts to create compression and, at the precise time, it releases that compression which, is NOT used as a power stage like normal. When that compression is released, since the engine is not creating power with it, it then becomes a braking system. This type of system IS adjustable. It's adjustable by simply switching either "HIGH" or "LOW" on the dash, or, on some higher end coaches, you'll have LOW, MED or HIGH, giving you three levels of auxiliary braking. It's normally found on the larger diesels in a bit more expensive coaches.

3. Retarder.
Well, as has been stated, most retarders, in the old days, were simply a device or, a set of valves, in the transmission, that would route the trans fluid to a point at which it is drastically slowed down and, that process would slow the transmission down to which, slowed the vehicle down. The problem with that system is/was, it created massive heat in that trans fluid. NOT GOOD!

4. "Telma Retarder"

This is by far, one serious braking device. We had them on all of our fire trucks. In short, it's nothing but a disc brake, WITH MAGNETS! Only, nothing every touches, like regular disc brakes. On ours, there were two large discs, attached to the drive shaft, near the differential. In between those two rotating discs, were eight, large coils. The ends of these coils were right at 1/16th away from those rotating discs.

There is a lever, about 4" high, on the dash of the fire truck. That lever has 4 detents in position. On approach to a situation where you needed to slow down, you'd pull forward one detent on that lever. That would electrically engage those coils. They would become an "Electromagnet". But again, they would not and could not touch the rotating discs. Now, if you wanted some SERIOUS STOPPING POWER, you'd immediately pull that lever on the dash to the forth detent. Talk about stopping power, yahoo, hang on 'cause you're stopping, all 66,000 lbs, RIGHT NOW.

As I stated, that is one serious auxiliary stopping device or brake. There may be some ultra-high end coaches with it but, I've not seen any. If you were to have a Jake Brake and, a Telma retarder, now you've got the most serious stopping power you can have, WITHOUT EVER TOUCHING THE SERVICE BRAKES

Waaaaaaay back before I retired, the option of having a Telma Retarder Option, when specking out new fire trucks, was $9,000. I have no idea what it would cost today.

But, one more thing. Obviously, the use of those coils means you need some SERIOUS Alternator power. All of ours were 450 amp alternators.
Scott

[MSHappyCampers]

Hi ! Welcome to IRV2! We're sure glad you joined the gang!

FIRE UP gave you a good summary!

Good luck, happy trails, and God bless!

[TonyMac]

My driveline is less than 3 feet long on my diesel pusher. I don't think I have much room available for a retarder. Some of the front engine, rear drive vehicles have a two drivelines each about 10 feet long with a carrier bearing in the middle. The forward driveline does not move in elevation, only the rear does. With this much room, one could add a retarder, but with 3 feet of driveline needing to move in the vertical for rear axle movement, I don't think it's possible.

[Mr_D]

Foretravel is the only production MH to use the Allison transmission with the retarder. It is considered to be an heavy use so the fluid needs to be TES-295 and changed more frequently.

[FIRE UP]

Originally Posted by TonyMac

My driveline is less than 3 feet long on my diesel pusher. I don't think I have much room available for a retarder. Some of the front engine, rear drive vehicles have a two drivelines each about 10 feet long with a carrier bearing in the middle. The forward driveline does not move in elevation, only the rear does. With this much room, one could add a retarder, but with 3 feet of driveline needing to move in the vertical for rear axle movement, I don't think it's possible.

TonyMac,
3 feet is plenty enough length for that Telma. Although, even if you were willing to fork out the $9,000 or more now, for that Telma, I'd definitely make a phone call to them before I'd even think about getting serious. And, as I stated earlier, you're gonna need a serious alternator and maybe a couple of extra chassis batteries. It's a great unit for sure. Before we started using them on our fire trucks, some of our rigs, especially the special permitted 70,000 lb rigs, would need a minimum of two complete brake jobs a year. The cost of the components needed and, the cost of the shop labor to do that, TWICE A YEAR, was way more than paid for with the install of that Telma. From that point on, the brake jobs on those rigs alone went to one every 3-4 years. Now, couple that Telma with a 3-stage Jake, most of our rigs, even the 5-7 year old ones, have yet to need replacement service brakes.

It also depends on the engineers and how well they handled their rigs in emergency and standard driving conditions.
Scott

[ThePowells]

Welcome to the forum!

[CountryB]

https://telma.com/videos/Telma_AXIAL...ilhome.mp4.mp4

[Gary RVRoamer]

Yeah, The Telma electromagnetic retarder is a terrific device, but a little out of the league for most motorhomes. Since high end coaches usually already have Allison trannies, they would probably opt for the Allison retarder (as Foretravel does). For example, Prevost offers either an engine (Jake) brake or Allison retarder. Same with Newell coaches, I think.