Air Pressure Problem?

[Adam Hicklin]

Wile driving the coach today, I was noticing that both air pressure needles on the dash air pressure gauge would vacillate between 95psi and 120psi.  This while cruising.  No brakes being used or any other air device.  As soon as it would get to 120psi it would bleed down to 95psi then climb back up in about a 90 second cycle.  I've never noticed this before but that doesn't mean it hasn't been happening all along.  Do I have a problem?

On another note, does anyone me of a place that can service the Meritor Air Brakes in the Los Angeles area!

Thanks in advance.

[Edward Buker]

Adam,

The suspension in these coaches use a lot of air employing fast acting leveling valves. Wind or bumps or changing road crowns all cause these valves to work to keep the coach level with the correct ride height. On a level smooth road I might get a minute between the compressor cycles, maybe 30 seconds when bumps etc are involved.

 If you come to a stop and sit at idle with the brakes held depressed for a period and released for a period of time you should see no loss of air except when you first depress the brake pedal. The needles should stay steady when you are not moving the brake pedal. That is a way to determine that the suspension is using the air while you are in motion and you are not dealing with some issue caused by an air leak.

Later Ed