Page 37 - 38. MRH13-04-Apr2013
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the front, with up to 110 cars. In the steam era, the loco ran
backwards. In the pre-radio days, the conductor would start
dumping air from his end (the caboose) if he judged the train
was moving too fast.
Travis added: “Milt pretty much nailed it on that one. In mod-
ern times you may see some distributed power on the rear
end, but what he said about the retainer valves pretty much
sums it up.” (Setting retainers reduced train line pressure,
allowing brake shoes to drag on the wheels, keeping the speed
of the train in check. See more at
)
Dave Husman pointed out that train handling techniques have
changed over the years as technology changes: “Power on the
point,” Dave said. “Unless the railroad has remote control or
DPU they probably wouldn't have power on the rear.”
Nick Brodar added another perspective: “If you needed helpers
on the way up, nowadays, many places leave them attached on
the way down for added dynamics. Midtrain or rear end.”
Dynamic brakes on diesel-electric and electric locomotives use
the traction motors as generators to increase rolling resistance.
The energy created is dissipated as heat through grids, or fed
back into the overhead wire system.
Ken Rickman, who is a locomotive engineer when he isn't post-
ing to MRH or scratchbuilding steam engines, added, “Since
the entire train would be descending the grade, the slack
should remain bunched. Modern practice would be to have
the locomotives on the head end, using dynamic braking if pos-
sible, or perhaps a combination of dynamic and air brakes.
As has been said, if the train had helpers of DP (distributed
power) units then they would likely be assisting in braking
as well.
