Tuesday, August 28, 2007



A typical road test in a Thomas School Bus, this unit has a Cummins ISB Model [electronic] Diesel Engine and when roadtesting it's always best to find a good grade to find any faults with performance.
Sometimes the transmission has to be considered if it's shifting poorly. If you're climbing a hill and the trans. upshifts too soon you'll start lugging the engine which feels like an engine power problem.

2 comments :

Jim Beal said...

Does that video show a Thomas with a problem or did it shift fine. I can't tell from the audio. Thanks.

John Whelan said...

Hi Jim,
This bus was shifting fine, it's an Allison electronic transmission 3000 series. I was just pointing out that checking out engine performance on a grade is the best way to detect problems. If the trans. is out of synch. with rpms then engine lugging happens which makes diagnosis harder.
tks for the comment, John.