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SD-03-904 |
Bendix® QR-1C™ Double Check and Quick Release Valve |
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Double Check |
Mounting Holes |
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Diaphragm |
Sealing Ring |
Balance Port(1) |
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Cap Nut |
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Supply |
Body |
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Port(1) |
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Sealing Ring
QuickRelease
Diaphragm
Delivery
Delivery(2) |
Cover |
Exhaust |
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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.
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
Identification
Mark
FIGURE B
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.
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.Awarranty 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.
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.
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 Tests.”
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.A1" 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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