The Stovebolt Site Forums The Parking Lot Big Bolts air disc brakes, input wanted

One place air is superior to hydraulic is in withstanding heat like you could see on a long down grade. I have seen brake fluid boil in wheel cylinders and the pedal goes to the floor until it cools. I don't think you want double acting or spring brakes on a steer axle so the air discs should work there. We don't have air disc brakes on the drive axles on any of the trucks where I work so I don't know if they would be a good choice on the rear, but air dics on front an air drums on back should be workable. Looking at the Haldex brochure you linked, it looks like they use a standard air chamber to operate so you would think it would be a simple matter to swap it out for a piggyback chamber on the rear to have spring brakes. The brochure dosen't go into a lot of detail but it says they can can be used on every axle so I would expect they offer them with spring brakes where spring brakes are DOT required equipment. We may have them on some of the new trucks, but for the most part we aren't using discs yet where I work. It sounds like new stopping distance requirements will have them on new equipment in the very near future.