DPU's

[ed1205]

    When running with a DPU does it throttle up when the lead units throttle or is there a delay and how do you control slack action? Is it same with maned helper units? What about mid train units?

[route_rock]

  The engineer controls the rear dpu from his screen upfront. Not much slack action can be felt as on a start most have the read unit pushing before they start the leaders.I have never experienced mid train DPU but I am going to assume it is just like a normal DP train.

 

 

[Mythod]

Unlike a manned helper unit the DP units are controlled by radio controls and yes they do have a delay you have to start like a conventional setup ie. notch 1 let it level out, notch 2 let it level out. and you can watch your screen to see whats happening on the DPU, which in my experience is running at around 85-90% power (notched out the head end will be pulling 50K the rear will be pushing 45k (made up numbers so don't say "it's wrong" I know!)). Slack action on a DP'd train is substantially lessened by the fact that the DP is pushing as the head end is pulling, and the brakes work alot faster do to air being released at both ends of the train keeping the trainline tighter. Mid DP's I would assume you would have to runn those like conventional train because you would be just pulling the last half of the train by them mid-DP's and all the hazards of starting would be in effect back there, Just my thoughts I have never ran a DP in the middle of my train only on the rear.

The manned helper poses other problem such as pop outs because the engineer on the rear end can overpower and pop cars out, they have to listen to the lead engineer and run the controls at a lesser power than the lead, which in many cases does not happen. I just want to get the guy over the hill and I am going to push him as hard as I can and have been lucky in not having any mishaps with overpowering the train. also the lead should be in control ove the train line air which doesn't happen because you would have to stop to uncouple, it's much easier to have a switchman on the front and give him a pin and watch the train go down the hill without stopping.