There seems to be a lot more automatic transmissions in on-highway dumptrucks. What are the positives and negatives for an automatic vs 18 speed fuller? Thanks in advance.
I think one of the positives of the auto is you can stick anybody that manages to get a license in it and not worry about clutch/driveshaft problems. Downsides: less power to the wheels, and burn some more fuel.
That's what a buddy of mine told me, who is the chief mechanic from a big dump hauler around here, too many drivers now days doesn't know how to properly operated a manual tranny and its related components, too many breakdowns, auto makes it more idiot proof.
I work for a municipal water district and we run Allison automatics in our 6 wheeler and our 10 wheel dumps. Along with our service trucks which have duramax Allison combos. Both of the dump truck see some moderate snow plowing duties each winter and they rock. I also am in a volunteer fire dept and all of our engines have Allision EVS series transmissions. They are great in a setting where you don't have assigned trucks. I find that the Allison's help keep the drivers from abusing the trucks. Sent from my iPhone using Tapatalk
The automatic's can crawl out of a hole in sand better. Just yesterday my 08 KW with Px8/ auto, had to pull my 08 Pete with Px8/ 8LL up a sandy hill after they had both dumped. The manual just wanted to bounce. Same suspension's under both... both the same wheelbase.
Under ideal conditions a manual may have a slight advantage over an auto, but in the real world the auto is usually better because it can shift to the proper gear while the driver is busy doing other things with his hands and feet. Same for power, and I would add to Grandpa's statement that it can usually upshift to a much higher gear/faster speed while climbing steep hills (faster being 10 mph vs 5 here) where with a stick you could never complete the shift before the truck stops. The only loss of power at higher speeds where it really matters is the oil pump and that can't be very big.