Old Jake brake thread. Brake saver retarder question

[BronsonA2150]

Found this thread from a long time ago someone was talking about a telma retarder. Sounds like it’s some kind of electric driveline retarder. Similar principle to Cat’s brakesaver. Were these or something else used very much on Mack’s since their jakes were less than stellar? 
 

 

[Geoff Weeks]

Telma's were more often found on buses.

1) they are silent, so not to alarm passengers,

2) they are heavy. Buses usually have less trouble keeping on the good side of weight law.

3) they are electric and can suffer from the gremlins common to high current electrical devices.

 

Cats "Brake saver" was hyd with engine oil being the medium used.  It was heavy when compared to a Jake or Macks retarder. The reason for it went away when Cat (and others) changed to common-rail injection. 

[Mark T]

Telmas were popular on packers (garbage trucks) too. Some Macks made to be packers had no provisions for an engine brake. Telmas would have been quiet in residential areas as well. Brakesaver ?  Whole different animal from back when Cats had overhead cams and an injection pump. Closest fluid type retarder would have been in an Allison automatic back then. Brakesaver was heavy, high maintenance and overall costly. Some 3406s still had them, but they were pretty much out of the picture by the mid to later '80s

[BronsonA2150]

2 hours ago, Geoff Weeks said:

Telma's were more often found on buses.

1) they are silent, so not to alarm passengers,

2) they are heavy. Buses usually have less trouble keeping on the good side of weight law.

3) they are electric and can suffer from the gremlins common to high current electrical devices.

 

Cats "Brake saver" was hyd with engine oil being the medium used.  It was heavy when compared to a Jake or Macks retarder. The reason for it went away when Cat (and others) changed to common-rail injection. 

So how heavy were the telma’s? Were they ever used in conjunction with a Jake brake like the brake savers were?

[Geoff Weeks]

The ones (Telmas) I was around were on LP fueled  M.A.N.'s so had a throttle and therefore would not work with a Jake. However if you could justify the weight there is no reason they couldn't be used with an engine Jake as well.

Some of the heavy hauler had 3406's with both Jake and Brakesaver, as weight is never an issue when every load is a permit load.

I don't know how much they weighed, but there was big rotor on the output (transmission) or input (rear axle) and a stator that surrounds the rotor with a series of electro-magnets in it. So lots of copper and iron. 

Brakesaver used engine oil to act on a turbine wheel between the engine and clutch. Retarding energy was turned into heat in the engine oil. Cats with Brakesavers have bigger oil coolers then those without.

When Cat used an injection pump and nozzles in the head, there wasn't a handy injector rocker to time the Jake like there was with Cummins and 2 stroke Detroits for optimal valve opening. Cat Jake's of that period used an adjacent cyl exhaust rocker to trip the Jake, but its timing wasn't ideal so the retarding wasn't as good as it is with common rail engines. So that is why the Brakesaver hung around until the changes over to common rail fueling. At that point the timing came from the injector rocker, like Cummins.

By the time we got the LP buses, mostly the Telam's didn't work, we had enough to do to keep the buses running and Telma's weren't needed in Chicago like they were in Austria where the buses came from. I think may be 1 out of 4 or so worked. Likely needed something simple, but there was never time. 

Edited 1 hour ago by Geoff Weeks