2020 Cummins IKE pull
VIDEO What do you think? (other than graphic error at 18:35 that says GMC DENALI :) ) For me, the time is about what I expected as it is missing a 10 speed auto and has slightly less power than ...
Forum Discussion
4x4ord wrote:
After thinking about the downhill test of these trucks here is what I have determined:
TFL guys said they had the Ford EB set to auto which is the best setting on the Ford for the downhill test they were doing. However there is more to it than picking a speed to hold the load at and measuring brake applications. For instance, The maximum reverse HP an engine can create occurs at maximum exhaust back pressure and engine redline. So 35 mph was an excellent speed for the Cummins to function at. It was running very close to the engine redline .... At the 4:00 and 6:00 minute marks in the video you can see the EB gauge all of a sudden display 236 reverse HP when the engine reaches redline. I believe the gauge is displaying while the computer applies the wheel brakes to prevent the engine from over revving. You can see that while the EB gauge displays the speed of the truck slows from 37 mph to 35 and then the wheel brakes are released.
If they had chosen 42 mph as the speed they wanted the truck to hold to the Ram would have had a disadvantage because the truck would have shifted to 3rd gear and the engine would have dropped to about 2400 rpm. At 2400 rpm the engine would have been producing considerably less reverse HP and as the truck accelerated Mr. Truck would have been applying the brakes prior to the engine reaching redline.
I didn't watch the Ford downhill portion again but I suspect they tried to go 35 mph with it as well. The Problem with that is 35 mph puts the Powerstroke in 3rd gear at 2800 rpm and in order to get maximum performance out of the Powerstroke EB they would have run the truck in 3rd gear at about 3400 rpm where it would have been travelling about 42 mph. Alternately they could have slowed the Ford to to get it to drop into 2nd gear and ran at 32 mph and 3500 rpm. Had the Ford been running at a higher rpm the computer would have been applying the brakes when the engine rpm reached redline.
I think the computer applies the wheel brakes at engine red line, so the Ram computer was performing multiple wheel brake applications where as the Mr Truck was applying the Ford wheel brakes prior to engine red line.
A tester really has to understand the workings of these trucks well to perform tests that demonstrate the full potential of each truck.
What does Mr Computer do if he overheats the brakes? Is he linked to an ejection function? Or does he know about all the run away ramps and is able to steer the truck to one? I wonder how the self driving semi's will handle this situation?
