speed control

Does the chicago subway system uses mechanical trip arms or a different system for controling train speed ?

Currently, the CTA uses a combination of cab signals and automatic block signals, depending on location. For a more detailed description...

http://www.chicago-l.org/operations/sig ... gnals.html

Mechanical trip arms are used to activate the emergency brakes if a train passes a red signal. I'm not sure if the term is still in use, but the device used to be informally known as a "rooster." The part on the train that strikes the trip is known as a "trip cock," a term that comes from the days when cars had air brakes and the device was connected to an emergency vent valve.

Such as seen on "The French Connection" with Gene Hackman.


A typical "L" ride in the first car, with speed control sound effects:

Accelerate
Accelerate
Accelerate

"beeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeep"

BRAKES
BRAKES
BRAKES

There's no middle ground on the L...

Sit in the rear facing seats at the front of the first car and hear the clacking and slamming of the control after the beeeeeeeeeeeeeeeeeep. Good stuff. Sometimes it sounds like a ratchet at a mechanic that went insane.

As an aside I've been taking the Ravenswood a lot at night lately and sitting in that set of seats looking through the front window. I'm surprised at how dark it is around the tracks. The headlights barely penetrate it. It's kind of spooky.