Today, I saw a DPU coal train on the BNSF line at Garretson,SD. Going up a grade, the two SD 70’s on the point were just cruising along. When the tail arrived,it had another SD 70 on the end that was just roaring! How are the DPU units handled? Are they set to run and brake the same as the lead engines? Or are they run independantly?
Thanks
They can be run independently.
Dave H.
Does the engineer then manipulate the throttle and brakes of the DPU seperately, or would he(or she) just put both ends at the same setting?
ind brakes on the dp mimmick the head end. dynos can be run independantly and throttle can be run independantly. Rear cannot be in dyn while head end is in power. Brake pipe is drawn down from both ends and charged from both ends as well.
Is the DPU run at a higher throttle setting,so as to somehow make it do it’s share of the work? Or, are all units run the same, and the power needs work themselves out? The reason I ask,is that the DPU unit I saw seemed to runninh at a much higher rev. than the 2 up front.
Thanks
I see the same operation here quite often. I wonder if the engineer is using the DPU to keep the train bunched and reduce slack action on the couplers and the rear of the train?
Murphy, could the lead units have throttled up after they passed you ? Perhaps they were clear of the Town and any speed restriction there. It might be hard to tell when the train is over a mile long.
the dp is often run at greater throttle than the head end
ironken: Thanks. I was thinking that the DPU was running a lot higher than the front engines. It’s quite possible,as nanaimo73 mentions,that the lead engines may have throttled up after they passed me,as they had just began to climb the hill. Does it complicate the job of the engineer greatly to run a train with DPU? It would seem that he would now have to be concerned with the throttle and braking of a locomotive a mile or so back and out of sight.
it can get complicated at times especially in undulating territory, but since they are primarily used on unit trains you don’t have to be as concerned about emptys/loads and where they are on the train. when they are used in the mountains it’s generally just full throttle or dynamics and air as needed. they are simpler to operate in tandem (DP’s copy the lead units) but you can run much smoother in undulating territory by splitting the fence (operating independently). especially when stopping and starting. it’s also easier to maintain track speed due to less slack action.
you can motor independently, or just put them in MU so they do whatever the head end is doing.
one engineer explained to me that the DPU set up was to allow a train to cover distance in a more even speed. The rear units keep the slack in and provide the boost to climb the profiles with a faster and more even speed. Around here all UP traffic is in a southbound direction and the UP unit trains usually have one unit at the rear in DPU mode, while the BNSF run thru coal trains usually use two units in DPU. I do not know why BNSF does this. Over on the KCS they run helpers mostly in the trains consist when
running southbound [ mountainous terrain south of Joplin,MO.] and it is not uncommon to see all the power on the head end when coming back northbound. Saw one Northbnd that had seven head end units, KCS, and UP.
Is there a difference between DPUs and helpers???
Thanks
DPU’s are at the end of the train while helpers are normally at the front (they CAN be in the rear, but it’s rare).
With DPU units there is only one engineer controlling the whole train. In other words all the helpers are controlled remotely from the front end. Helpers that are not DPU are maned by a engineer also. Typicaly DPU units stay with a train from terminal to terminal. Maned helpers will usualy run back and forth helping many trains up a grade (or down a grade for more dynamic brakeing.