"Plugging" a Diesel electric locomotive will really stop things. The
first "thing" is the rotation of the motors; the second thing that
usually stops is your continued employment with the RR.
Damaged traction motors, abused switch gear and badly flattened
wheels are not the stuff of which happy Master Mechanics are made.
The only sanctioned use of "plugging" is usually associated with the
need to control extremely slow speed operations during the loading or
unloading of trains. DC locomotives are incapable of producing
sufficient retardation in dynamic braking to control speeds in the
range required to load, for instance, a coal train. If loading is
downhill the engine is reversed BEFORE movement starts. As the train
begins to roll the throttle is advanced one or two notches and
a "balancing act" begins. Electrical energy is now being applied to
resist the forward rotation of the motors (wheels). As speed
increases additional power is applied to maintain the target speed.
When throttle position 5 cannot control the speed it is prudent to
use a little air and reduce a few notches. The sequence is then
repeated until loading is complete. No damage occurs to either the
locomotive or your job.
MAC locomotives have a different method of generating dynamic brake
forces, they go into reverse to produce retardation. Going into
reverse is, however, completely controlled by the computers with
which the locomotive is equipped. The electrical energy supplied to
the motors is carefully applied to prevent wheel slide. A MAC can be
controlled to nearly a dead stop when in dynamic braking.
I know the Q did not have MAC's but since the thread contained a bit
of dynamic brake discussion I thought I'd throw it in.
Karl
------------------------ Yahoo! Groups Sponsor ---------------------~-->
Buy Ink Cartridges or Refill Kits for your HP, Epson, Canon or Lexmark
Printer at MyInks.com. Free s/h on orders $50 or more to the US & Canada.
http://www.c1tracking.com/l.asp?cid=5511
http://us.click.yahoo.com/mOAaAA/3exGAA/qnsNAA/8ZCslB/TM
---------------------------------------------------------------------~->
Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
|