TM 55-2210-224-34
4-15. A-1 CHARGING CUTOFF PILOT VALVE (cont)
TEST
26.
Test the A-1 charging cutoff valve in accordance with New York Air Brake Company Test Specification NYT-560-C.
The A-1 charging cutoff pilot valve functions as follows:
a.
During normal brake operation, the A-1 charging cutoff pilot valve will be in its normal position as follows:
(1)
Main reservoir air will bepresent in chamber A, beneath the cutoff piston head to hold it in its upper
position. Chamber B beneath the cutoff piston spool valve will be connected to exhaust via port 53
and the cutoff pilot valve exhaust in the automatic brake valve on leading units.
(2)
Chamber C, above the cutoff piston and port 9, is connected to exhaust via the actuating piston spool
valve and automatic sanding timing choke.
(3)
Brake pipe flows through port 1 to chamber D surrounding the back side of the actuating piston,
through the choke in the piston to chamber E at the outer face of the piston, and though port 11 to the
90-cubic-inch (1475 cc) volume reservoir, charging the volume reservoir and both sides of the
actuating piston to brake pipe pressure.
(4)
Port 35 and the chamber beneath the dynamic cutout switch are exhausted through the cutoff piston
spool valve.
4-80
