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Hector Duplichen On Suspensions/Level low- Awesome
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Jon , yes confused for sure but that’s ok . I do not watch TV so now I have something else to read about . Thank you
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Susan
I have a ’91 with replaced bags and vvlues and it drops down on the right rear first also. Maybe it is conpensating for this left leaning State (OR)..
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Greg, far more information is needed. To start, has your coach been modified or is it original with respect to if the system logic was changed.
Early coaches had to maintain at least 35 PSI accessory air pressure otherwise the tag air bags would exhaust pressure and the rear would drop.
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This is an excellent article! Unfortunately, I am having a difficult time reading the labels and legend on the schematic diagrams. Is it possible to get a copy of the diagrams in JPG format at 300DPI?
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If I understand your request….????
Go here and get the diagram for your VIN.
Enlarge it as much as needed.
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Thanks, Tom. I already have the Prevost pneumatic diagram for my coach. I was most interested in the color diagrams offered in Jon’s document. Unfortunately, when I print the document the words and legend run together making it almost impossible to read. I am not sure if it is my computer/printer or the font used in the diagrams. See attached from page 3 of Jon’s document.
Jeff and Lindsay
91 Marathon XL -
I have another version of of Hectors PDF drawings that is kind of, sort of, interactive in the sense that you can click on the switches in the drawing with the mouse pointer and it will show you the changes that occur on the spot. Having said all that I don’t really have a way to easily share the intact PDF.
However, I did send you an email titled Hectors PDF. It’s not spam.
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I think it is great folks want to understand the level low / suspension system. But try not to get too involved in the minutia. There are only two reasons I can think of to have a superficial understanding.
The first is if the coach will not respond to a desired action, like not coming to ride height or not going up or down at one point when in manual mode. In that case start by looking for power to the appropriate solenoid valve on the manifold in the steer compartment, and if power is there verify air flow thru the solenoid valve to the appropriate Norgren valve or valves. Then verify the final valve(s) are functioning and flowing or exhausting air.
The second reason is for leak detection. Knowing the system basics allows the leak chasing to be isolated to the appropriate and limited section.
There was a time way back before Tom was taking my dues money that people who had the leans were finding service providers were spending days spraying soapy water under the entire bus to find a leak that was likely associated with a couple of air bags and some hose and fittings from a Norgren valve.
Everybody should keep in mind Prevost has had multiple variations of the suspension and level low systems including system logic. To add to the number of variations some converters have modified the systems with their designs or added features to the Prevost basic system. That is why I do not suggest trying to understand the systems in detail, but to focus on the underlying operational principles.
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Yes, I did receive your email, Tim. Thanks again for the detail. It will help diagnose my problem.
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Your XL2 will not match Hector’s diagram. Yours has IFS and as such it is going to have “ping” tanks and instead of a 5 port Norgren controlling the steer axle suspension I think you are going to have a variation that uses 2 3 port Norgrens.
I have not looked at the Prevost pneumatic diagram, I am just making an educated guess.
The operating principle is the same.
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