BENDIX R-6 RELAY VALVE Manual

®
® ™
Bendix R-6 Relay Valve
SERVICE
PORT
SUPPLY PORT
(RESERVOIR
MOUNT TYPE)
SUPPLY
PORT
FIGURE 1
DESCRIPTION
The relay valve in an air brake system functions as a relay
station to speed up the application and release of the brakes.
The valve is normally mounted at the rear of the vehicle in
proximity to the chamber it serves. The valve operates as a
remote controlled brake valve that delivers or releases air to
the chamber in response to the control air delivered to it
from the foot brake valve or other source. The R-6
valve is a piston operated valve. For ease of servicing, an
"insert" or "cartridge" type inlet/exhaust valve is employed.
This feature permits service of the inlet/exhaust valve without
line removal. The R-6 ™ relay valve may be mounted directly
to or remotely from the reservoir which provides its supply
pressure. Standard porting consists of one (1) service port
and four (4) delivery ports. There are two (2) supply ports in
the reservoir mounted valve and one (1) supply port in the
remote mount valve.
DELIVERY
PORTS (4)
EXHAUST
™
RETURN
SPRING
FIGURE 2
OPERATION
APPLYING
Air pressure delivered to the service port enters the small
cavity above the piston and moves the piston down. The
exhaust seat moves down with the piston and seats on the
inner or exhaust portion of the inlet/exhaust valve, sealing
off the exhaust passage. At the same time, the outer or inlet
relay
portion of the inlet/exhaust valve moves off its seat, permitting
supply air to flow from the reservoir, past the open inlet valve
and into the chambers.
BALANCED
The air pressure being delivered by the open inlet valve also
is effective on the bottom area of the relay piston. When air
pressure beneath the piston equals the service air pressure
above, the piston lifts slightly and the inlet spring returns
the inlet valve to its seat. The exhaust remains closed as
the service line pressure balances the delivery pressure.
(NOTE: Some valves are equipped with a piston return spring
which will assist the lifting of the piston). As delivered air
pressure is changed the valve reacts instantly to the change
holding the brake application at that level.
RELAY PISTON
R-6 ™ RELAY
VALVE INSERT
1