I was in Alberta, Canada last week and saw quite a few long freight trains (Canadian Pacific). It's not a sight I ever see where I live on Long Island. Most consists that I've seen have at least 2 diesels pulling from the front. However, during this trip, I saw a few that had pullers in the front and another midway through the consist. Seeing that made me wonder.......how is the engine in the middle of the consist controlled by the lead engine? How do they communicate?
-Roger
Replies sorted oldest to newest
There aren't enough freight customers in LI to generate the kind of traffic that makes for really long trains like the one you saw. The circus train is probably the longest consist the LIRR sees.
As for the locomotives in the middle of the train, that's call "distributed power" This Wikipedia article should answer most of your questions.
---PCJ
What you saw is called a "DPU", a distributed power unit controlled from the lead unit by a radio signal. BNSF and Union Pacific use them frequently in unit trains.
Do they ever run into problems with control of those middle engines if the radio signal fails?
And a second question......if there are two in the front and one in the middle and a long consist......what would be a typical crew size?
-Roger
Do they ever run into problems with control of those middle engines if the radio signal fails?
The DPU control computers are designed so that in the event of a loss of radio communications, the remote unit/units will stay in their current state for so many minutes, unless an air brake application is sensed. Then the unit droops its load and returns to idle. It is a bit more complicated than that, but you get the basics.
And a second question......if there are two in the front and one in the middle and a long consist......what would be a typical crew size?
One Engineer and one Conductor, in the lead, controlling unit.
-Roger
Thanks, guys. Fascinating stuff
-Roger
What you saw is called a "DPU", a dedicated power unit controlled from the lead unit by a radio signal. BNSF and Union Pacific use them frequently in unit trains.
"DPU" is DISTRIBUTED Power Unit, NOT DEDICATED Power Unit
Many American railroads out west used DPU'S. The Rio Grande on the Tennessee Pass would have two units mid train to get the tonnage over the top. Very cool indeed.
I was wondering about that.
Thanks challenger398 I made the correction.........
WLE (Wheeling Lake Erie) uses remote control units on the Westland Spur to the Marcellous Gas collection site. Westland Spur is an old Montour Spur that was re-tracked recently. The remotes are used as pushers. (2)Grades to Westland are difficult.
ROGER1,
What is a "Lash Up"? Please explain:
"Pappy"
Pappy,
My impression of the term "lash up" is when 2 or more locomotives are connected together. If I'm wrong on that, someone please jump in.
Roger
Pappy,
My impression of the term "lash up" is when 2 or more locomotives are connected together. If I'm wrong on that, someone please jump in.
Roger
It is strictly a railfan/model railroader term. Only if units were "lashed together" with rope or cables would it be used. The correct term, used throughout the railroad industry, is "MU consist".
Access to this requires an OGR Forum Supporting Membership
