Originally Posted by stemo76
2000 Harney once made by Safari.
Doing more research I see that normal air brakes take pressure to apply the brake and only the park brake uses mechanical brakes in which air is used to keep off.
So I am guessing that the rear discs are double duty, with an inner drum design like a modern car.
Yes that's how it works.
Air over hydraulic brakes have air activated master cylinders. They are basicly an air chamber, bolted to a master cylinder.
Most have a indicator rod and over travel switch to let you know how much MC travel you have. The pedal will feel the same, even with no brake fluid.
Air over hyd. brakes have been used on heavy, constrction equipment for years. Wow, back in the 70s. Seen them on standard drum, wedge drum and disk brake systems.
I believe the spring activated, air, parking brake is a smaller drum, inside the rear rotors.