How does the Jacobs Extarder work?
My m/h is a 1994 Allegro Bus, 5.9B 230 hp (mechanical engine) Cummins DP. It is equipped with a Jacobs Extarder. From what I understand, to stop confusion in what it's called, it is now just called ...
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What you have sounds similar to the PacBrake on our Safari – exhaust brake only. Our engine is electronically controlled. Anyhow . . .
When I switch on my PacBrake, my 6-speed Allison transmission shifts down to 5th gear and I can feel the braking. The previous owner told me he had things reprogrammed to automatically downshift only this far. I understand the factory default was second gear (I assume it did the shifting incrementally) which gave more braking than he wanted.
I can still push the button to downshift and the lower gears provide even more braking in the event I should need it. But I’ve been pretty impressed with the ability of the PacBrake to hold my speed on some pretty long and steep hills here in WV with shifting down only to 5th gear.
If yours does not downshift automatically, I assume you need to downshift manually.
Wayne
When I switch on my PacBrake, my 6-speed Allison transmission shifts down to 5th gear and I can feel the braking. The previous owner told me he had things reprogrammed to automatically downshift only this far. I understand the factory default was second gear (I assume it did the shifting incrementally) which gave more braking than he wanted.
I can still push the button to downshift and the lower gears provide even more braking in the event I should need it. But I’ve been pretty impressed with the ability of the PacBrake to hold my speed on some pretty long and steep hills here in WV with shifting down only to 5th gear.
If yours does not downshift automatically, I assume you need to downshift manually.
Wayne
