Bendix Commercial Vehicle Systems SR-1 SPRING BRAKE VALVE - Manual

1
®
SD-03-4508
Bendix ® SR-1 ™ Spring Brake Valve
1/4 P.T.
RES. #1
1/4 P.T.
DELIVERY
1/4 P.T.
SUPPLY
FIGURE 1 - BENDIX ® SR-1 ™ VALVE EXTERIOR AND SECTIONAL VIEW
1/4 P.T.
CONTROL
DESCRIPTION:
The Bendix ® SR-1 ™ spring brake valve is used in dual
or “split” air brake systems equipped with spring brake
actuators. The function of the SR-1 valve is to supply a
specifi c, limited hold-off pressure to the spring brakes, and
in the event of the loss of No. 1 service air pressure, to
modulate the spring brakes through the use of the service
brake valve.
The valve has four identifi ed 1/4" N.P.T.F. ports and a
diaphragm protected exhaust port. Two 5/16" diameter
holes are provided in the integral mounting bracket of the
valve body. The SR-1 valve must be mounted with the
exhaust port down toward the road surface.
OPERATION - INITIAL AIR SYSTEM CHARGE
Air fl owing from the No. 1 reservoir only enters the reservoir
port of the SR-1 valve. This air remains under piston A as
system pressure builds. With No. 1 reservoir pressure
below approximately 55 P.S.I. the spring above piston A
forces it into contact with inlet and exhaust valve A causing
the exhaust to seal and the inlet to open. Refer to Figure 3.
With air system pressure above approximately 55 P.S.I. in
No. 1 & 2 service reservoirs, piston A has moved against
the force of the spring above it, allowing the inlet of valve A
to close and opening the hollow exhaust passage through
piston A. Refer to Figure 4.
PISTON SPRING
(14)
O-RING
(LARGE)
(18)
PISTON SPRINGS
(14)
COVER (13)
PISTON (15)
PISTON O-RINGS
(16)
VALVE (12)
VALVE SPRING (11)
VALVE STOP (10)
O-RING (9)
CAP NUT (8)
PISTON (17)
O-RING
(SMALL) (19)
BODY
CHECK
VALVE SPRING (2)
PIPE PLUG
(1)
CHECK
VALVE (4)
EXHAUST
COVER (5)
DIAPHRAGM
(6)
INLET &
EXHAUST
VALVE (7)