Braking on a Steep Grade

[wolfe10]

Planocat,

There is a lot of confusion over the term Jake brake.

There are two types of brakes on diesel engines:

Exhaust brakes-- basically a "potato stuck in the tail pipe" that the pistons have to work hard against. These are generally used on smaller diesel engines (up to about 9 liters).

Engine compression brakes, more generally known as a Jake brake-- open the exhaust valve as the piston approaches TDC on the compression stroke, releasing all the energy stored in the compressed gas out the exhaust pipe. Used on larger diesel engines.

The confusion comes in because Jacobs Corp makes BOTH an exhaust and engine compression brake. So, some call their exhaust brake a Jake brake (made by Jacobs Corp).

Others, with a Jake brake (engine compression brake) also call theirs (rightly so) a Jake brake.

Brett

[planocat]

Brett:

Guess I used the wrong term........ should have referenced Jacobs "driveline retarder" which was also commonly referred to as a "Jake Brake"

From one of the other diesel forums:

"Magnetic driveline brakes are extremely effective, although somewhat expensive. In a nutshell, magnets surround the driveshaft, and when the juice is sent to the retarder, the magnets exert braking force on the driveshaft.There are at least three or four brands, one from France (Telma), one from Germany (KB?), one from Spain (KLAM) and one from Japan (Voith division of Sumitomo Metal Industries). Jacobs, the "Jake Brake" folks, made them until around 1999, but stopped making them and referred their old customers to the other brands.

They are often used on International V8 diesel-powered school buses in the high mountains of Colorado and other states along the Continental Divide. One huge school district on the west side of Denver goes all the way to the Continental Divide to pick up school kids. The parents demand super-safe school buses, so the district spends several thousand bucks extra per bus to be certain the buses can stop when "comin' down the mountain".

Sorry for the confusion.

[wolfe10]

Yes, there are two more "devices to slow you down". One is the drive line retarder you mention-- not aware of any RV manufacturers who used them.

The other is a TRANSMISSION RETARDER. Foretravel and, I understand, Prevost use them. The transmission will be a 3000R or 4000R. Very expensive and even more powerful than a compression brake.

[planocat]

It was not at all uncommon to find them on 80's Wanderlodge Bluebirds. My Bluebird was a 1983 model.

[dwightginnyputzke]

Prior to the mid 1970s the Bluebird Wanderlodge had a 6-speed Allison with a integral hydraulic retarder ( at no extra cost ) that provided the best downhill mountain braking available. Then Allison Transmission stupidly discontinued the transmission forcing Bluebird and others to look for an alternative.

In 1996 I was invited as part of a group of 50 people from North America that were flown in for a several day all expenses paid in the mountains of Arizona and the General Motors Test Track to introduce a new model of Allison Transmission with a integral hydraulic retarder for school buses to show how this new system could improve over the old system of brake failures in downhill mountain driving.

[ClayL]

FWIW Jake brakes come in three flavors nowadays.

1) compression release brake

2) bleeder brake

3) exhaust brake

For explanations on how they work go to their SITE and look under "Technology" at the top.

The following came from the owners manual on the last motor home I had. It had a P30/32 chassis. It might be helpful to the OP who said he had a P30 chassis as I recall.

When Using Transmission to Brake.

Maximum Speed in First Gear is 30 MPH.

Maximum Speed in Second Gear is 40 MPH.

[wolfe10]

Clay,

Indeed there is a lot of confusion about auxiliary brakes on a diesel.

Jacobs corporations and many others (like PacBrake) make exhaust brakes.

Many corporations also make Engine Compression Brakes. Just as Xerox is often used to mean "copy", Jacobs is often used to mean Engine Compression Brake, since they are a major manufacturer of them and have been for many decades.

I have never seen a bleeder brake on an RV -- would be interested in a reference to an RV with this new-type of brake. Says it requires a VGT or exhaust brake in addition to the bleeder brake for "maximum performance".

[ClayL]

The bleeder brake is new to me. I saw it for the first time when I was on the site.

Doesn't sound like something we will see on the average DP does it?

[Homesteader]

Just to add to the discussion, the reference to an engine compression brake being commonly called a Jake brake, is because Jacobs was the first to design and manufacture this device.

As a point of interest it was by accident that it worked as a braking system, as the original purpose was to keep the operating temperature up on engines in west coast logging trucks while descending long hills that would normally cool right down.