Bendix QR-1C DBL CHECK QUICK RELEASE VALVE User Manual

Bendix® QR-1C™ Double Check and Quick Release Valve

Mounting Holes

Cap Nut

Sealing Ring

Double Check

Diaphragm

SD-03-904

Balance Port(1)

Delivery (2)

FIGURE A

DESCRIPTION

The Bendix® QR-1C™ is a dual function valve. The valve’s
primary function is to serve the emergency side of a spring
brake actuator as a quick release valve. In addition, it
functions as an anti-compound device. The double check
valve prevents a service and emergency brake application
from occurring simultaneously .
The QR-1C™ valve is generally mounted on the axle and
serves two spring brake actuators. The air connections to
the QR-1C™ valve are as follows:

1. QR-1C™ valve delivery port (2) connected to emergency
port of spring brake.

2. QR-1C™ valve balance port (1) connected to delivery of
brake valve or relay valve. NOTE: If relay valve is installed
on vehicle, it should be connected to the delivery side
(not service or signal side).

3. QR-1C™ valve supply port (1) connected to delivery of
park control valve.

Supply
Port(1)

Quick Release

Delivery

Cover

In its standard configuration the valve is designed to deliver
within 1 psi of control pressure. However, for special
applications the valve is available with greater differential
pressure or zero hysteresis. QR-1C™ valves also come with
optional noise reducing foam crosses or silencers. Some
QR-1C™ valves can also come with biased double check
valves. These double check valves contain a beaded seat
cap nut (Figure B). The bias design minimizes low differential
leakage.

Beaded
(Biased) Seat

Non-Beaded

Exhaust

Diaphragm

Body

Sealing Ring

FIGURE B

Identification

Mark

1

OPERATION

SPRING BRAKES RELEASED

When the spring brakes are released, air from the park control
valve flows through the QR-1C™ valve, causing the double
check valve and quick release diaphragms to flex and seal
the balance and exhaust ports. Air flows into the emergency
port of the spring brakes from the QR-1C™ valve delivery
ports.

DISASSEMBLY

Mark the relationship of the body and cover before disassembly.

1. Remove cap nut.

2. Remove sealing ring from cap nut.

3. Remove double check valve diaphragm.

4. Remove four Phillips head screws.

5. Separate the body and cover and remove the sealing
ring and quick release diaphragm.

SPRING BRAKES APPLIED

When the spring brakes are applied, supply line air pressure
to the valve is exhausted through the park control valve. As
air pressure is removed from one side of the double check
valve and quick release diaphragms, they flex in the opposite
direction opening the balance and exhaust ports. Spring brake
emergency pressure is released at the exhaust port of the
valve while the small amount of air trapped between the two
diaphragms is released through the relay valve or brake valve
exhaust.

ANTI-COMPOUNDING

When a service brake application is made with the spring
brakes applied, service air enters the balance port and flows
through the valve into the emergency ports of the spring
brakes. This prevents the compounding of a service and
spring brake application. Service air passing through the
valve flexes the double check and quick release diaphragms,
sealing the supply and exhaust ports. When the service
application is released, air is exhausted from the spring
brakes.

PREVENTIVE MAINTENANCE

Important: Review the Bendix Warranty Policy before

performing any intrusive maintenance procedures. A warranty
may be voided if intrusive maintenance is performed during
the warranty period.

No two vehicles operate under identical conditions, as a
result, maintenance intervals may vary. Experience is a
valuable guide in determining the best maintenance interval
for air brake system components. At a minimum, the
QR-1C™ valve should be inspected every 12 months or 3600
operating hours, whichever comes first, for proper operation.
Should the QR-1C™ valve not meet the elements of the
operational tests noted in this document, further investigation
and service of the valve may be required.

REMOVAL

1. Block vehicle wheels and/or hold vehicle by means other
than air brakes.

2. Drain all air brake system reservoirs.

3. Identify and disconnect air lines from valve.

4. Remove mounting bolts, then valve.

CLEANING AND INSPECTION

Clean all metal parts in mineral spirits. Wipe all rubber parts
clean. It is recommended that all rubber parts and any other
part showing signs of wear or deterioration be replaced with
genuine Bendix parts.

ASSEMBLY

1. Install sealing ring on cap nut.

2. Install double check valve diaphragm in body .

3. Install cap nut and torque to 150-400 inch pounds.

4. Install sealing ring in valve body .

5. Install the quick release diaphragm in the cover .

6. Install the cover and diaphragm on body, aligning the
marks made during disassembly . Secure together using
the four Phillips head screws and torque to 30-60 inch
pounds.

7. Re-install the QR-1C™ valve and before putting the vehicle
in service, perform the “Operation and Leakage T ests.”

OPERATING AND LEAKAGE TESTS

Before performing these tests, park the vehicle on a level
surface and hold the vehicle by means other than the brakes.

1. With the park control valve in the released position, note
that the spring brakes are released.

2. Remove the air line connected to the QR-1C™ valve
balance port and apply a soap solution to the exhaust
and balance port. A 1" bubble in 5 seconds is permissible
at either location.

3. Reconnect the QR-1C™ valve balance line; and using
the park control valve, park the vehicle. NOTE: A prompt
application of the spring brakes with an exhaust of air at
the QR-1C™ valve exhaust port.

4. Remove the air line connected to the supply port of the
QR-1C™ valve. With a service brake application hold
applied, apply a soap solution to the supply port and
around the seam between the body and cover. A 1" bubble
in 5 seconds is permissible at the supply port. No
leakage is permitted between the body and cover.

5. Reconnect the supply port air line. If the valve does not
function as described, or if leakage is excessive, it is
recommended that it be replaced with a new or
remanufactured unit, or repaired with genuine Bendix parts.

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