What is the difference between radio controlled helpers and DPUs?
Radio controlled helpers are now called DPU.
If you use the term helper, a manned helper is meant nowadays.Regards, Volker
Normally, helpers are used for short term power on grades. DPUs stay with a train the whole way since they are part of the road power needed to move the train under normal conditions. If a train needs 3 locos to do a run, you can put 1 in front, one in the middle and one on the rear if you want. You have 3 locos, doesn't matter where you put them. Now if you need more power for a grade or mountains, you add manned helpers to the consist for the time needed.
This recent thread might help.
http://cs.trains.com/mrr/f/13/t/269772.aspx
Steve
If everything seems under control, you're not going fast enough!
pajrrYou have 3 locos, doesn't matter where you put them. Now if you need more power for a grade or mountains, you add manned helpers to the consist for the time needed.
If the necessary tractive effort of the locomotives to pull a train exceeds the coupler strength you can't put all locomotives at the head end. Otherwise the coupler might break a coupler. Next step you put locomotives at the end as they are easier to add or to remove.
UP has a chapter about helper placement in its System Special Instruction.
Locomotive information starts on page 33, helper placement on page 46. What is missing is the TE requirement for the subdivisions.
Nowadays trains get even over mountains with just DPUs. What once were helper districts often only have DPUs now. Helpers were once the norm currently they are more the exception from the rule.Regards, Volker