They can be used to decrease warm-up time at idle. Even a few minutes goes a long way. Not the same as a "jake brake" a compression release device used on Class 8 trucks, but the same effect in using exhaust backpressure to slow the rig in coming down to a stop. (Service brakes can last over 200k with the right driver exercising prudent use of these devices; my own experience in the oilfield with a variation of this truck type is that is unmatched for bringing a 30k+ rig to a town speed limit while on a non-Interstate highway).
Probably the reason DD wants to avoid them -- with an apparent "rule" about
no engine braking while underway -- is also the "no idle" rule, etc.
Jacobs Exhaust Brake
Pacific Brake PRXB
These have been stock on CTD's since late 2007 (and a dealer option for about fifteen years before that). A CTD with the six speed manual
and an exhaust brake has a wide range of stopping performance choices available to the driver. A marriage made in heaven. (Now, if only we had a seven speed manual with [2] overdrives optimal for both solo and "towing heavy").
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