A lift axle control module is disclosed that is simpler than prior art
lift axle control systems, and does not require cycling the input
pressure to the regulator. The module includes a housing fluidly
connected to a first pressurized air supply and having one chamber with a
load bladder port, a second chamber with a lift bladder port, and a
common vent port. A pilot pressure is selectively provided for switching
the module between the retracted and deployed modes. When the control
module is set to the retracted mode, the lift bladders are pressurized to
the system pressure, and the load bladders are vented. When the control
module is set to the deployed mode, the lift bladders are vented and the
load bladders are inflated and maintained at the regulated pressure.