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“Depending on the grade, the tonnage, and the situation, there
is a possibility that an engineer who was using air brakes alone
might have to pull the slack out, pulling against the brakes
without releasing them. This could be because a section of
the grade is not as steep, and the braking force needed else-
where would stop the train on that portion, or because he for
whatever reason used more air than was needed to control
the speed. I have seen this happen in situations where some
braking is needed, but the minimum reduction which will allow
a running release (releasing without stopping the train) is too
much and will unduly slow or stop the train. Still, in all these
situations, the locomotives would be on the head end.”
Tom VanWormer explained how it was done in the days of
full crews: “The train would be inspected by the crew and car
inspectors at the station at the top of the grade. The crew
would set all of the retainers. You could only have one car
without air brakes for every four cars with air brakes. All of the
air brake-equipped cars would be behind the engine and the
cars without air brakes would be at the end of the train.
“The brakemen would all be "decorating" the car tops with each
brakeman responsible for four cars. When the engineer whistled
for brakes, they would tighten down the brakes on their four
cars, and then be prepared to tighten them down again when
the engineer whistled for brakes again. When the train reached
the bottom of the grade it would stop to cool the wheels, release
all the retainer valves and unwind the brake wheels.”
Mike Ruby added “show” to the show-and-tell:
“On the next page is a video
(2)
on my layout of a train
descending a 4% grade. I also run trains with a rear DPU. The
area I model has done both ways. Spreading the locos through
the train reduces the forces trying to derail it. I don't need the
locos for the descent but do require the power for the climbs.
Questions, Answers & Tips - 4
The complete thread is at
mrhma
.
– MRH Forum
Q.
I need to understand the math to install an Atlas #3.5 wye
(3) to connect two parallel tracks to converge via the wye into
one track. The center lines of the parallel tracks will be 3 to 4
inches apart, depending on what radius and length of track I
need to make this work. I will be running passenger cars, so it
is critical that I have good length and radii for this.
– Moose2013
A.
Responders took a pragmatic view.
“Moose, you are over thinking the problem,” said Tom
VanWormer. “What railroad are you modeling? What era? In
the 1970s the double track center line was normally 16 to 20
feet apart. In the '20s to '50s the track center line was 13 feet.
For a high speed passenger line give yourself two passenger
lengths to transition from the wye to the mainline track so
you don't induce any S curves into your track and lay your
track by eye. That way your passenger trains will smoothly
transit the track.”
MRH-Apr 2013
