Charging Spring Brake Actuators Below 107 Psi; Charging Spring Brake Actuators Above 107 Psi - BENDIX SR-7 SPRING BRK MODULATING VALVE Applications

CONTROL LINE PRESSURE
SECONDARY RESERVOIR
CONSTANT PRESSURE
INLET / EXHAUST VALVE OPEN
FIGURE 5 - CHARGING LESS THAN 107 PSI
CHARGING SPRING BRAKE ACTUATORS
BELOW 107 PSI (FIGURE 5)
With the air brake system charged and the parking brakes
released (by pushing the dash valve button in), air enters
the park control port. This opens the SR-7
air pressure to the spring brake chambers. As illustrated,
air pressure in the chambers is below 107 psi (nominally).
CONTROL LINE PRESSURE
SECONDARY RESERVOIR
CONSTANT PRESSURE
INLET / EXHAUST VALVE SEATED
FIGURE 6 - CHARGING GREATER THAN 107 PSI
4
à
à
à
™
valve to supply
à à
à
BALANCE PORT
CONTROL PORT
DELIVERY TO SPRING BRAKES
à
CHARGING SPRING BRAKE ACTUATORS ABOVE
107 PSI (FIGURE 6)
Once the SR-7 ™ valve delivery pressure reaches 107 psi
(nominal), the inlet and exhaust are closed (valve lap
position). This maintains the spring brake hold-off pressure
at 107 psi (nominal).
BALANCE PORT
CONTROL PORT
DELIVERY TO SPRING BRAKES
à