1999 Beaver Marquis - Parking Brake Not Working

[Devin Ginther]

Need some education.  Pulled manuals and tried searching on topic.  Now I am a bit confused about the particular system on our Marquis, too. 

The Magnum Chassis Manual mentioned both hydraulic over hydraulic OR air over hydraulic.  But nothing about air brakes with no hydraulics.

I am obviously no expert but have always thought our Marquis was purely an air brake system (owned for about 6 mos) like semi trucks.  Installed the Air Force One and only saw standard air brake relays. 

Am I completely missing something?

Second, I cannot find any information on adjusting the parking brake setup on this rig.

Our parking brake does nothing so really like to get it working prior to a big summer trip. 

Some education on this system and tips would be appreciated. 

[Eric Maclean Co-Admin]

Devin

On the Magnum chassis there where two types of drive line parking brakes used the earlier models used a drum brake mounted to the rear of the transmission and some of the latter Magnum chassis used a disc brake mounted to the rear of the transmission.
Both used a remote spring applied maxi brake chamber and a cable to the brake itself.

Maxi chamber

https://www.fleetpride.com/parts/haldex-spring-brake-chamber-ma15500x?shopping=true&gad_source=1&gclid=Cj0KCQjw4v6-BhDuARIsALprm32IM8shZbU6CeKFzYK7ay9O6ojC86xPUYLJEwPRUpoHSb1GS3ZW6QoaAkJDEALw_wcB

Disc brake assembly

https://www.hayesperformance.com/heavy-equipment-brakes/m100lm

With this system there is a large spring inside the maxi chamber that applies the parking brake via cable and when air is applied to the maxi chamber the spring is compressed which releases the tension on the cable and in turn releases the parking brake

If one of these two types of brakes fail to hold the vehicle it is a result of either a mechanical issue like pads / shoes worn out or sized operation
Or more than likely the large spring in the maxi chamber is broken and not capable of applying enough force to apply the parking brake hard enough to hold the vehicle.

Hope this helps
Eric