| Author |
Message |
Bob Wood so cal (4.63.41.14)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 10, 2004 - 5:33 pm: | |
i have been looking at both. anyone have a retarder on a 740? do you like it? thanks in advance! Bob |
Bob Wood so cal (4.63.41.14)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 10, 2004 - 6:36 pm: | |
i think i answered my own question from the archives, any other input still appreciated, Bob |
H3Jim (68.105.103.139)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 10, 2004 - 7:06 pm: | |
I just talked to a charter opertator in El Cajon, CA. who has both the exteranlly mounted retarder on the driveshaft as well as Jakes. He also runs both the two stroke and four stroke detroit diesels.
His take is he would choose Jakes anytime he has a choice, no questions. In his opinion, the only downside to the Jakes is noise, but when you're inside the bus who cares anyway, and they are cheaper to install and maintain. He stated that the replacement coils on his retarder cost about the same as a totally new Jake installation, and must all be replaced at the saem time if any single one is damaged. He says it says on the owners manual for the retarder not to run at level 5 (of 1 to 5) for more than several minutes, however if it takes 10 or 15 minutes to get down a long grade, is there a driver that won't use all that it has? The resultant heat eats up the retarder, and any nearby bearings and seals which aren't cheap either. Even the lower settings produce significant amounts of heat which over time degrade all nearby components.
He went on to say that the four strokes seem to have less slowing power than the two strokes if neither one has a Jake or other engine braking system. His conclusion is that for series 60 etc, he wants a Jake and only a Jake on it.
And don't even talk about the retarders internal to the transmissions. Trannies produce heat, too much by themselves, and break down over time due largely to that heat. And then to add a component that produces massive amounts of heat and bury it in the heart of the transmission? The world trannies he says cost you $10k just to open them up, so the last thing you want is another heat source inside the thing.
Keep in mind that this perspective is from an operators point of view. As an owner driver, you are better prepared to drive it with the care required. Of course these things still apply when you are purchasing the coach, since the coach will not have been driven by the owner.
My own personal experience is limited to only a before and after with a series 60 and a Jake. I really like the Jake a lot, and consider it minimum safety equipement.
740's are more bullet proof than the world, but heat gets to everything. |
James Maxwell (Jmaxwell) (66.81.54.174)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 10, 2004 - 8:28 pm: | |
There is a big difference in the operation of Telma retarders and hydraulic built into the trans. Telma induction retarders are certainly huge heat sinks that must be operated within certain parameters. Likewise, so must the internal hydraulic type employeed by Allison, but that does not make them inherently inferior to Jakes, in fact, they have several advantages over Jakes, although Jakes are cheaper to buy and install. And, Jake use is highly restricted in a lot of areas and have a design characteristic of diminished effectiveness at low rpm, low speed. My retarder works down to 0 mph right in the heart of town. |
Bob Wood so cal (4.63.41.14)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 10, 2004 - 8:59 pm: | |
thanks guys! i already have the retarder in the 747, and i will be getting jakes aws well. all the best friends! Bob |
|