PART NO : AB8491                           
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Relay valves are primarily used on long wheelbase vehicles to apply and release rear axle(s) service or parking brakes. They are air operated, graduating control valves of high capacity and fast response. Upon signal pressure from the service brake valve, they graduate, hold or release air pressure from the chambers to which they are connected.

• A fast relay used to apply and release service brakes on tractor or trailer.
• Compact size.
• Two port delivery.
• Two mounting holes, .34 diameter on 1.50" centers.
• Cover may be rotated without affecting warranty or performance.
• Picture illustrates 90° control port position. 0° would locate port in line with delivery port "D".

SUPPLY A:  1/2"

SUPPLY B:  1/2"

DELIVERY C:  1/2"

DELIVERY D:  1/2"

CONTROL PORT:  1/4"

CONTROL POSITION:  ​90º

CRACK PRESSURE:  5.6 ± 1.0 PSI

CROSS REFERENCES:
A78887, N30108BF, 9732980140, 28520, AE78887, N30108AH, 459790C91, 110412, 14036, 70017261, 767653010786, 035058.
A cross reference listing means that this valve is a suitable replacement for the part numbers listed. Some changes in air line plumbing may be required.