Air-Hydraulic Power Brake System for M35A2 Deuce and a Half, Converting from Air-Pack Air-Over-Hydraulic

Replacement parts for the original Air-Pack system are getting harder to find, and what is available is generally of low quality. This converts it, with all brand new parts, to reliable and much more supportable air brake parts. Converting to Air-Hydraulic makes everything the same as full air-brakes, except that you don't have to change the hydraulic brake axles to do it.

Our Air-Hydraulic brake system uses an air-valve/pedal assembly to apply a remotely mounted air brake booster. It uses air pressure from a belt driven or 12 volt onboard air system to control the Air-Hydraulic booster, just like the brake system on super sized big rigs and buses, but it pushes a master cylinder rather than the roller cam that mechanically spreads the brake shoes apart on full air brake systems, so it will operate the existing hydraulic brake calipers or drums. It is great for vehicles with a lot of horsepower, a lot of weight, limited firewall clearance, that don't have power steering pressure or enough vacuum to run other brake systems, and/or already have air tanks onboard for operating air-ride suspension or air powered tools.

Most of the system is mounted remotely, usually on the frame or in the trunk. The only thing that attaches to the brake pedal is the air-foot valve, which is about the size of your fist, so the stock pedal can even be removed altogether and replaced with a pedal that we supply that mounts on the floorboard with the valve going on the other side of the floorboard. There will be an air hose that will go from the air tank to the valve, along with another air hose that will go from the valve to the service port on the air brake booster/master assembly that is on the frame supplying boost for standard pedal application of the brakes. The booster has two chambers, one does the normal brake application, and the other is the emergency/parking brake. Another valve which can pushed and pulled to manually apply a hydraulic parking brake that locks all four wheels, a hose will go from the tank to this parking brake valve, and then from the valve to the other port/chamber on the brake booster. The parking/emergency brake valve can be mounted on the dash for easy access, or hidden under the seat or dash to conceal access to it. The hydraulic parking brake feature is much more powerful than the common cable parking brake, can serve as an anti-theft device if the valve is hidden, and is there to also apply the brakes if the vehicle loses air. The system can be built with just the service chamber and no parking brake chamber if it is unneeded or unwanted in your application. If a set of glad hands is also installed, this system will allow a vehicle with hydraulic calipers or drums to pull a trailer that is equipped with air-brakes, or a trailer with hydraulic wheel cylinders that also has one of these Air-Hydraulic systems installed.

It operates off of 120-150 pounds of air pressure, which is much higher than the 15-20 pounds of vacuum that vacuum brake setups use (if the engine is producing enough, or any, vacuum), and is more serviceable than Air-Pack systems that are no longer generally used. We also build a conversion for the Air-Pack to the Bosch Hydro-Max® that has a backup motor that assists in stopping if your engine dies, which is a great feature, the Air-Hydraulic likewise will have 10-20 or more power assisted stops in reserve in the air tank if the engine dies, and the air compressor will continue to produce more if the battery still provides electricity. More air tanks, compressors, dryers, and other air brake accessories can be added in for increased redundancy just as with standard air brake systems.

Our systems can be setup with or without an air compressor and tank, and can easily be designed to replace other obsolete systems with just a few measurements - like the master cylinder bore diameter of your current setup. Dual/split systems with multiple boosters and master cylinders that are isolated front and rear are also available and would be used for redundancy/safety or for a "limp home" mode so that one half of the brake system will work if the other fails.