R-8 relay valve for rear brakes on the M939 series without ABS. P/N 11669105 / 288781. NSN 4820011079695.
Supply ports are 3/4 inch NPT. Delivery ports are 1/2 inch NPT. Service port is 1/4 inch NPT. Installation requires reusing pipe plug from existing relay valve (1/4 inch NPT) on 3rd delivery port.
Two relay valves used on the M939 series, one for each rear axle. (sold individually)
The relay valve in an air brake system functions as a relay
station to speed up the application and release of the brakes.
The valve is normally mounted in the proximity to the
chambers it serves. The valve operates as a remote controlled
brake valve that delivers or releases air to the chambers in
response to the service control air delivered to it from the control