M923 External Air

[IronGiant5Ton]

Good Afternoon Gents,

Task: Hook up an air compressor to an m923 so kids can honk the horn at touch a truck event without running the engine.

I have combed steel soldiers and reviewed fold outs for the air system on an m923a2.

It looks like the best way to do this is to put a QD on the front service air connection under the bumper. From the air diagram it looks like it leads back to the wet tank with no check valves inhibiting pressurization of the wet tank.

The other option is to remove a vent valve from the passenger side between the tool boxes and replace with a ball valve and QD.

Request ya'lls input for the best way to do this or if you have done this before? Thank you guys.

V/r
Max
U.S.N. Ret.

 

[Jbulach]

I would look into isolating the horn completely from the rest of the air and electrical system. That way you can keep the air tank drains opened/spring brakes engaged and the starter, as well as the rest of the trucks electrical system disconnected…

 

[Jbulach]

I’m not around my truck this week, but what I suggested “should” be fairly easy. Tee in a quick coupler and add a check valve just before the horn solenoid on the firewall that is just before the horns. The electric side, IIRC the horn button completes the ground side of the circuit? If so you can likely break into the positive side at the horn solenoid with a two position switch, with one position for normal operation, then the other position feeding from it’s own, fused power wire straight from the battery’s, or positive wire on the starter solenoid. PLEASE double check me on the polarity and routing of the wiring, BEFORE you attempt any of this!