American Train Braking Explained

THE STANDARD AMERICAN SELF-LAPPING BRAKE WORKS AS FOLLOWS:; THERE ARE SIX BRAKE NOTCHES; RELEASE,HOLD, LAP, APPLY (OR SERVICE), HANDLE OFF, AND EMERGENCY. - RELEASE: TAKES OFF THE BRAKES BY FILLING THE CYLINDERS TO THE STANDARD FREIGHT PSI OF 90, OR PASSENGER; 110 PSI. - HOLDING: RELEASES THE BRAKES ON ALL OF THE TRAIN, EXCEPT ON THE LOCOMOTIVE. IT HOLDS THE SAME BRAKE POSITION. - LAP: KEEPS THE SAME PSI ON THE WHOLE TRAIN, AS AFFECTED BY: - APPLY (SERVICE): DECREASES THE AMOUNT OF AIR IN THE CYLINDERS. ONCE THE DESIRED BRAKE FORCE IS REACHED, MOVE BACK INTO LAP. - HANDLE OFF: WILL DECREASE THE PSI ALL THE WAY TO ZERO IN MOST CASES. THIS IS WHAT THE HANDLE MUST BE IN WHEN THE LOCOMOTIVE'S BRAKE STAND IS NOT BEING USED. - EMERGENCY: IMMEDIATELY DUMPS ALL AIR FROM THE CYLINDERS, USED IN EMERGENCIES, OBVIOUSLY.