Bendix Commercial Vehicle Systems RE6 User Manual

Bendix® RE-6™ and RE-6NC™ Relay Valves

RELAY PISTON

EMERGENCY

PISTON

SD-03-1151

SERVICE

PORT

O-RING

SEALING

RING

™

RE-6
Valve

MOUNTING

FLANGE

RE-6™ & RE-6NC™
Valves

RESERVOIR

PORT (2)

™

RE-6NC

ID TAG ATTACHED

SEE (FIGURE 2)

VALVE

SPRING

DIAPHRAGM

DELIVERY PORTS

(4)

SCREW

SERVICE

PORT

EMERGENCY

PORT

WASHER

CHECK VALVE

DELIVERY

PASSAGE

CHECK VALVE

DELIVERY

PASSAGE NOT

PRESENT

CAP

SCREW

INLET AND

EXHAUST

VALVE

EMERGENCY

SUPPLY PORT

CHECK VALVE

SPRING

RE-6NC
Valve

™

CHECK

VALVE

NOT

PRESENT

FIGURE 1 RE-6™ & RE-6NC™ RELAY VALVES

RE-6™ VALVE DESCRIPTION

The RE-6™ valve is used in dolly and trailer brake systems.
It is a dual function valve, combining the functions of a relay
valve and an emergency valve.

The relay function is identical to that of a relay valve, a
remotely controlled brake valve. Control pressure from the
towing vehicle is routed through the trailer service line and

RE-6NC SPECIAL
XXXXXX
SVC. REPL. XXXXXX

FIGURE 2 RE-6NC™ RELAY VALVE SPECIAL
IDENTIFICATION TAG

1

CONTROL LINE

Service Brake Chamber

Slack Adjuster

Trailer Gladhand

FRONT

SUPPLY LINE

R-12P
Valve

™

Single Check
Valve

Reservoir

Bulkhead

™

SV-4
Valve

RE-6™ RELAY VALVE DOLLY SYSTEM CONFIGURATION

Trailer Gladhand

Drain
Valve

Service Brake Chamber

Slack Adjuster

RE-6
Valve

™

CONTROL LINE

™

R-12P
Valve

FRONT

Bulkhead

Single Check
Valve

SUPPLY LINE

RE-6NC™ RELAY VALVE DOLLY SYSTEM CONFIGURATION

FIGURE 3 - RE-6™ & RE-6NC™ RELAY VALVES SYSTEM CONFIGURATION

2

Single Check
Valve

™

SV-4
Valve

Reservoir

™

PR-3
Valve

Drain
Valve

™

RE-6NC
Valve

on to the relay portion of the valve. The emergency function
of the valve automatically applies full trailer reservoir air
pressure to the trailer chambers when the trailer supply
pressure falls below a predetermined minimum value.

™

The RE-6

/RE-6NC™ relay emergency valve may be
fl ange or reservoir mounted. Ports are clearly identifi ed for
delivery, service, emergency (supply) and reservoir lines.

RE-6NC™ VALVE DESCRIPTION

The RE-6NC™ valve is a special non-charging relay
emergency valve. It is used on dollies to comply with
FMVSS 121. The RE-6NC™ valve eliminates the need for
a protected reservoir to provide the release air for the trailer
spring brakes when the following requirements are met:

- The trailer supply line must be 70 psi minimum with any
leakage-type service system failure.

- The parking brake must not drag at trailer supply line
pressures above 70 psi.

The relay function of the RE-6NC™ valve is identical to that
of the RE-6™ valve, serving the dolly or trailer system as
a remote controlled brake valve. The emergency function
of the valve automatically applies full trailer reservoir air
pressure to the trailer or dolly chambers when the trailer
supply pressure falls below a predetermined minimum
value. The major difference between the RE-6™ and the
RE-6NC™ valve is that the RE-6NC™ valve allows supply
pressure (initial charge) to release the spring brakes before
the dolly or trailer reservoir(s) is fi lled.

RE-6™ & RE-6NC™ VALVE SYSTEM
CONFIGURATION

In the RE-6™ valve dolly system, the supply air fl ows to the RE-
6™ valve, passes through the valve, holding the chambers in
the apply position while simultaneously fi lling the reservoir.
In the RE-6NC
supplied through the RE-6NC
valve system. The supply air fl ows to the RE-6NC™ valve,
acts upon the emergency piston, pushing the emergency
piston toward the inlet / exhaust valve seat. System
pressure in the chambers and reservoir are still at 0 psi in the
RE-6NC

™

In the RE-6NC
PR-3™ valve, which will allow the air to fl ow on to the
reservoir at a pressure setting of about 70 psi. The major
difference between the RE-6™ valve and the RE-6NC™
valve is that the RE-6NC™ valve does not require the
system to charge the reservoir to a predetermined psi
before drive away is allowed. Refer to Figure 3.

™

valve dolly system, reservoir air is not

™

valve, as it is in the RE-6™

valve system, allowing for faster trailer pull-away .

™

valve system, air is also fl owing to the

EMERGENCY

SUPPLY

RESERVOIR

45 PSI

CHAMBERS

45 PSI

45 PSI

RE-6™ Relay Valves

45 PSI

0 PSI

0 PSI

RE-6NC

FIGURE 4 RE-6
BELOW 45 PSI

CHARGING THE RE-6™ & RE-6NC™ VALVES
BELOW 45 PSI

When the air brake system is charging below 45 psi,
emergency supply air enters the RE-6™ and RE-6NC™
valves emergency port. In the RE-6™ valve the air acts on
the check valve and the emergency piston. In the RE-6NC™
valve the air acts on the emergency piston, because there
is no check valve present. This allows for faster drive away
(reference FMVSS 121 regulation). In the RE-6™ valve, the
supply air is forced past the check valve, fl owing through
the emergency piston shoulder and past the inlet / exhaust
valve. The air fl ows to the upper portion of the valve,
underneath the relay piston and out to the service brake
chambers while simultaneously fi lling the reservoir with the
same air that is passing through the emergency piston. In the
RE-6NC™ valve, air is only acting upon the emergency
piston. The check valve is not present. In replacement
of the check valve, the RE-6NC™ valve uses a reservoir
control valve (the Bendix® PR-3™ valve), to allow the
reservoir to be fi lled. The PR-3™ valve is totally separate
from the RE-6NC™ valve, but is necessary for proper
operation of the RE-6NC™ valve. Air acts on the PR-3™
valve piston, but will not fl ow on to the reservoir until about
70 psi. Refer to Figure 4.

™

& RE-6NC™ RELAY VALVES CHARGING

™

Relay Valves

3

RESERVOIR

45<>60 PSI

EMERGENCY

SUPPLY

45<>60 PSI

RESERVOIR

60 PSI

EMERGENCY

SUPPLY

60 PSI

45<>60 PSI

CHAMBERS

HOLDING

RE-6™ Relay Valve

45<>60 PSI

0 PSI

0 PSI

RE-6NC™ Relay Valve

FIGURE 5 RE-6™ & RE-6NC™ RELAY VALVES CHARGING
HOLD POSITION

RE-6™ & RE-6NC™ VALVES CHARGING HOLD
POSITION

In the RE-6™ valve, as pressure increases in the reservoir,
the emergency piston is being pushed toward the seat on
the inlet and exhaust valve. When the emergency piston
reaches the seat of the inlet / exhaust valve, air is trapped
between the new seal and the chambers, holding the
chambers in the apply position. The check valve in the
RE-6™ valve will continue to remain open, charging
the reservoir. In the RE-6NC™ valve, air is acts on the
emergency piston, but there is still 0 psi in the reservoir
and the chambers. Air is also acting on the piston in the
PR-4™ valve, but still has not reached the opening pressure
of 70 psi. Refer to Figure 5.

CHARGING THE RE-6™ & RE-6NC™ VALVES
ABOVE 60 PSI

In the RE-6™ valve, as pressure increase beyond 60 psi, the
emergency piston and the inlet / exhaust valve, move from
the seat of the primary piston, opening the exhaust valve to
atmosphere allowing the service chambers to be exhausted.
The air will fl ow from the service chambers, back through
the RE-6™ valve and out the exhaust of the RE-6™ valve,

CHAMBERS

0 PSI

RE-6™ Relay Valve

60 PSI

0 PSI

0 PSI

RE-6NC™ Relay Valve

FIGURE 6 RE-6™ & RE-6NC™ RELAY VALVES CHARGING
ABOVE 60 PSI

allowing drive away . In the RE-6NC™ valve, air is still acting
upon the emergency piston, but there is no pressure in the
reservoir and the chambers. The emergency piston and

inlet / exhaust valve have moved to the exhaust position,
opening the exhaust portion of the valve to atmosphere.
The PR-3™ valve remains closed until reaching 70 psi,
allowing air to fl ow to the reservoir. Refer to Figure 6.

CHARGING THE RE-6NC™ VALVE ABOVE 70 PSI

Once system pressure reaches 70 psi, the PR-3™
reservoir control valve will open charging the reservoir(s).
Simultaneously the emergency piston and inlet / exhaust
valve of the RE-6NC™ valve is kept away from the seat
of the primary piston (keeping the exhaust valve open to
atmosphere). This is the major difference between the
RE-6™ valve and the RE-6NC™ valve. The RE-6NC™ valve
allows for quicker drive away , since the reservoir does not
need to be fi lled before the brakes are released. Refer to
Figure 7.

4