AUTOMATIC BRAKE VALVE (cont)
Install cutoff pilot valve position selector plug (13) and secure with retaining ring (12). Check that circular
projection on one face of cutoff pilot valve position selector plug extends into spool valve chamber.
Turn in regulating valve adjusting handle (6).
Install handle (3) on cam shaft (24) in HANDLE OFF position and secure with washer (2) and retaining socket-head
screw (1) move handle (3) to RELEASE POSITION.
Test the automatic brake valve in accordance with Test Specification T-2646. The automatic brake valve functions
RELEASE Position. This is the position of the automatic brake valve for charging the brake pipe and brake
system and for releasing an automatic brake application. In this position the valve functions as follows:
(1) Main reservoir air enters port 30 and flows as follows:
(a) To the supply portion in the relay valve.
(b) To the supply portion in the regulating valve.
(c) To the spool of the suppression valve, where it is trapped.
(d) To the spring chamber of both the emergency valve spool and the suppression valve spool. Air
pressure is trapped in the spring chamber of the emergency valve spool.
(e) Through the suppression valve spool to passage 3, where it is directed to the spool of the cutoff pilot
valve; through the valve to passage 7; and to the underside of the emergency reservoir cutoff pilot
valve. Air pressure raises the piston of the valve and unseats it.
To spillover check valve A, through the valve, to the spool of the cutoff pilot valve, where it is trapped.
(2) Equalizing reservoir air pressure is developed as follows:
(a) Regulating valve pressure setting is adjusted by turning adjustment handle A. This opens the supply
seat of the valve, and main reservoir air pressure enters the equalizing reservoir charging passage and
flows to the equalizing reservoir cutoff valve.
(b) Equalizing reservoir air pressure flows through the equalizing reservoir cutoff valve and out port 15.
(c) From port 15, equalizing reservoir air pressure flows to the equalizing reservoir, to the air gauges, and
to port 5.