Abstract: To unload a lengthy object from a transport trailer, the rear of the trailer is supported by legs and the bogie wheels at the rear are shifted fowardly. As they reach the front of the trailer, they are automatically coupled to the tractor and the tractor is disconnected from the trailer. The bogie wheels continue their forward motion and push the tractor from beneath the trailer. The rear of the trailer is then lowered to the ground and the lengthy object is released from the trailer and slides into engagement with the ground. Thereafter, the trailer is driven forward by the tractor, while coupled to the bogie wheels, until the object is unloaded. The rear of the trailer is then raised by the legs and the bogie wheels are shifted rearwardly to their initial position, whereby the tractor is pulled into coupling engagement with the trailer and the bogie wheels are released from the tractor.