Trailer auto inflation system question

Meritor does.

 

Hendrickson uses a regulator in the control box. They have a complete manual on their website.

 

The O-rings in the valve extension hoses are easily damaged during tire changes. You have to be gentle when reconnecting the hoses to the "T" in the hub.
I carry a few spares.

Also sometimes a tire tech will turn the center "T" counterclockwise to get hoses to reach, that could allow air to escape. Sometimes the tension of the hoses can turn the "T" with the same result.

Spray with soap water to find leak.
As mentioned it could be your tank or system that leaks, not the tires.

Good luck

 

Most likely you have either an inflator hose that is not installed correctly/cross threaded and it's leaking, or possibly an internal air leak within the wheel hub assembly. Our 3 axle container chassis have auto inflators, inside the hub is a "stator" assembly and they randomly will start to leak, sometimes you can hear them, sometimes you can't. Improperly installed inflator hoses is incredibly common.

 

Some of the systems will have a built-in regulator, usually a it's a giant screw knob you can adjust it one way or another, other systems may have the regulator installed inside the box with the shut-off. Our tri-axles came unregulated and would inflate to 140 psi (where the gov. on our tractors were set), company took it apart and installed a regulator on it and set it 100 psi. Back when the UPRR had inflation systems on UP 53' chassis, not uncommon to find one set to 125 PSI or 60 PSI. We had a tire blow out, when the tire guy was servicing it on the side of the road, he checked the PSI system and found it was inflating tires to 125 PSI. He adjusted it back to 100 PSI and deflated each tire to 80 PSI before he turned it back on.