An improved axle load-distributing device detachably mounted on the rear of a vehicle for transferring a portion of a load from the rear axles of the vehicle to the wheel supported axle of the load-distributing device. The device, which includes a wheel mounted frame assembly and pneumatic units operably connected thereto, is further provided with a tracking unit operably connected to the pneumatic units of the device which partially deactivates the pneumatic units when a predetermined angular relationship between the vehicle and the load-distributing device is detected by the tracking unit.