4-11. AUTOMATIC BRAKE VALVE (cont)
SUPPRESSION Position. This portion of the brake handle is provided for reset of a safety control penalty brake
application. Although this position is to the right of FULL SERVICE position, no further reduction of equalizing
reservoir pressure will be made beyond that already attained at FULL SERVICE.
(1) When brake handle is placed in SUPPRESSION position, suppression valve spool will be displaced fully
inward by the handle cam.
(2) Main reservoir air pressure will be trapped in the spring chamber of the spool and port 3 will continue to be
(3) Main reservoir air pressure will be directed to port 26 and suppression pipe port 8; the lock-over pipe will be
blocked by the valve spool in suppression position.
(4) Air pressure on port 26 is used to suppress the safety control brake application valve, and blocking of port 8
will reset the safety control brake application valve.
HANDLE-OFF Position. This position is provided to allow the brake valve to be cut out when the locomotive is
(1) In HANDLE-OFF position, suppression valve is positioned as it is in SUPPRESSION position. The
regulating valve cam, however, is moved to allow the regulating valve spool to move fully away from its
adjustment spring tension.
(2) If the brake valve handle is placed in HANDLE-OFF position and removed, equalizing reservoir air pressure
will be reduced to atmosphere and safety control will be suppressed, allowing the brake valve to be cut out
and left unattended.