BENDIX TCH-003-043 Manuel d'utilisateur télécharger pdf

Technical Bulletin

Bulletin No: TCH-003-043-A Effective Date: 11/28/00 Cancels: NA Page: 1 of 1

Subject:

ZERO HYSTERESIS QUICK RELEASE VALVE

Bendix Commercial Vehicle Systems changed all QR-1, QR-N2, and QR-1C quick release valves having a

maximum differential of 1 PSI (TMC I.D. QRV-010) to be zero hysteresis (TMC I.D. QRV-000). All valves

having a differential greater than the 1 PSI maximum were not impacted by this change. This change was

implemented on 10-15-97 as a product improvement for both service and park brake systems. Bendix and other

industry groups recommend that the pressure at all axles of a combination be within 2 PSI for control line

pressures of 10-40 PSI (Ref: BW-1555). This pressure balance promotes brake balance provided other factors

such a brake type, friction formulation, tires, etc. are sized properly per the gross axle weight regulations

(GAWR).

SAE J1859 defines hysteresis as the difference in the increasing and decreasing input pressure for a given output

(delivery) pressure. Conventional quick release valves with hysteresis can have a differential (difference between

inlet and outlet pressure) as high as 20 PSI on release. The zero hysteresis enables the output pressure to be equal

for both increasing and decreasing pressures. This improves the pneumatic brake balance on release and enables

the recommendations for pneumatic brake balance to be met.

The quick release valves manufactured by Bendix are flow sensitive devices that require a certain flow rate to

provide quick exhausting of air pressure. Because of the nature of its operation, line sizes and delivery volume are

critical to rapid exhausting of the delivery pressure.

Bendix recommends 3/8” tubing (outside diameter) minimum for Supply, Balance and Delivery lines for

these Quick Release Valves. If smaller line sizes are to be used, or if the venting of supply pressure is restricted

by other components, BCVS recommends that the zero hysteresis type quick release valves not be used to ensure

proper quick release function.

Bendix has released the following quick release valve part numbers with a 1 PSI maximum differential for use

with smaller line sizes and unique application. These are not zero hysteresis quick release valves.

Port Size (NPT)

Part Number Model

Supply Delivery Balance Exhaust

5009069 QR-1C 3/8 3/8 ¼ --

5008064 QR-1C ¼ 3/8 ¼ --

5009070 QR-1C ¼ ¼ ¼ --

5009071 QR-1 3/8 ¼ -- --

5009009 QR-1 3/8 3/8 -- 3/8

5009073 QRN-2 3/8 3/8 -- --

Technical BulletinBulletin No: TCH-003-043-A Effective Date: 11/28/00 Cancels: NA Page: 1 of 1Subject:ZERO HYSTERESIS QUICK RELEASE VALVEBendix Comm

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BENDIX TCH-003-043 Manuel d'utilisateur