Jake Brake / Pac brake question
I may be asking a dumb question but I am researching for future DP purchase. I have a gasser and have never owned a DP but have been looking at a lot of them. Is the type of supplementary braking writ...
Forum Discussion
jplante4 wrote:
The Pac brake is not just an exhaust brake. It works in conjunction with the ECM to pre-select a lower gear (4th or 2nd depending on the programming) and will downshift to a lower gear as soon as the ECM figures it can without exceeding max RPM. Proper use of a Pac brake is to switch it on (some people leave it on all the time), then apply the service brake until the downshifting starts. Additional service brake applications may be required on downgrades. You step on the brake and force the coach to slow down, let the downshift occur and then let the Pac brake control the speed. If you need another downshift, you use the service brake to slow down to force a downshift.
I find that it's best to use the service brakes for limiting the RPM, as well. Not that the speed might become excessive in a steep downgrade, but as the tranny downshifts, the rpm's can climb dangerously high.
