The down shifting of the trans can mask an improperly operating EB cylinder action. By observation you can determine the piston / PAC operation is normal by the deceleration of the MH. Down shifts when the circuit is activated are gauged by the distance it takes to stop using telephone poles as a measure. Typically they are spaced 100 feet apart. At 50 mph we can slow to 20 mph in about 250 feet with the PAC. note: (it was cheaper to get it, the piston, at Freightliner than a Cummins)
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