My understanding of how the brake system works on fright cars is that the air is used to hold the system open, not closed. If that is the case, how are train cars rolled down hills in switch yards? Shouldn‘t the car stop on its own shortly after being uncoupled?
Not if the brakes are open manually and the wheels arent chucked.this is apractice that used to be used quite frequently.(bumping the yard)
you will shop gasoline yet you larger have a instruction manual transmission for the shift into kit on the backside of the hill. i think of you ought to blow out an automated transmission. additionally, how steep is the hill? while you are attempting to apply Georgia overdrive on Bland hill in VA you larger have actual grade brakes or be arranged to apply the run away truck ramps.
The air brake system on a freight car consist of a two part reservoir called an auxiliary reservoir, which has an auxiliary reservoir section and an emergency reservoir section. When the control valve on the car receives the signal through a reduction in the brake pipe it directs auxiliary reservoir air into the brake cylinder of the car, thus applying the brakes. When the car is detached or if a brake pipe reduction is made at an emergency rate, the control valve also signals the emergency reservoir section to also send it's air into the brake cylinder. Once the car is detached and the brake cylinder is charged, a bleed rod can be pulled that exhaust the brake cylinder air through the retaining valve. Usually when a train is received in a yard it is bleed off by either a utility employee or a car man. Then the cars are free to be switched and kicked without worry of the brakes being applied. There is one small difference between the draw down of the air system. If a train is known to be receiving an inbound inspection by car men, the engineer will move the automatic brake to continuos service and this will draw down the auxiliary reservoir section but keep the emergency reservoir fully charged. If the cars are simply cut off and the cars go into emergency application both reservoirs are depleted. Either way pulling the bleed rod will release the air in the brake cylinder and thus release the brakes for easy switching.
