I've gotten into DCC speed-matching most of my locos, and since I'm running modern-era, I like to have DPUs (Distributed Power Units) at the rear of my long trains. I've noticed though that most DPUs face backward, but some face forward. Does it make a difference, or is there a reason for it to face a certain way?
On P&W NR-2 the DPU is backwards so they never have a facing point switch on their run to New London. They could use the Wye in Groton, but ive never seen them do it, probably to limit the time they are on the NE Corridor.
BMMECNYC On P&W NR-2 the DPU is backwards so they never have a facing point switch on their run to New London. They could use the Wye in Groton, but ive never seen them do it, probably to limit the time they are on the NE Corridor.
Dave H. Painted side goes up. My website : wnbranch.com
Yes, thank you for the correction. What I had intended to say before my coffee was they use DPUs so that they can do all the switching going one direction or the other. They usually run 3 units. 2 on the south end and 1 on north end on the southbound trip. In the days before they scrapped the B-units, they ran with one cab facing each way. They still run 3 units, and the north end unit faces north, but the second south unit may be found facing either direction. It may depend if they are dropping a unit in Groton or not (as was the case this last Thursday). The reasoning behind the placement of the north side engine is for the trip north without a run around. I have also seen the second unit (or both) run around the train and put on the head end for the trip north.
I don't keep up on modern stuff all that much. One issue I know that used to come up was some locos didn't have ditch lights on the rear of the unit. I think with the passage of time, that's much less of a factor, but maybe someone with more trackside time than me could tell us more? Because if called on to lead gotta have the right lighting for the road.
Mike Lehman
Urbana, IL
BNSF does not have rear ditch lights on their DPU units. They still operate them short hood forward, as they do not need ditch lights when travelling at the end of a train. The headlight is kept on, but dimmed. As Mike notes, this does make it easier to bring the DPU to the front if needed.
No difference excpet perhaps for visibility when running light. D&RGW ran engines in whatever direction they needed although in most cases engines were positioned with short hood facing out on each end of a helper sets for visibility when returning to base after helping a train.
Obviously with engines facing both directions on power sets, direction basically doesn't matter as far as traction and power goes.
Rio Grande. The Action Road - Focus 1977-1983
I watch the CN on the former WC / SOO in SE WI., and I've seen DPU's mid-train, and EOT, and I see locos in each direction. Maybe it has something to do with the direction of the loco when it was added to the train.
Mike
My You Tube
I think the way the DPU faces is related to the service the train is in. If it will be engaged in switching, the DPU will probably be facing the rear to facilitate reverse/facing point moves. A train that will not do any switching would have the DPU facing the head end of the train. Actually, on a train that does no enroute switching, the first thing on the ready track is grabbed, regardless of orientation. Down here on the UP, I have seen DPUs coupled nose to nose on the rear of a train, so, do what suits your needs with 'em.