A wheeled bogie unit is engageable with one end of a chassis of a treatment plant to support that end of the chassis above the ground for the suspended transport of the plant. The bogie unit has a chassis, at least one wheel set supporting the chassis, a lifting cradle mounted on the chassis and having a projecting end which is engageable with the end of the plant chassis, a support and guide surface provided on the projecting end of the cradle which is engageable with a lifting surface provided on the end of the plant chassis, in order to suspend one end of the plant chassis above the ground, and a slide mounting the cradle on the bogie chassis for relative slidable movement between a lowered position and a raised lifting position. In the lowered position, the end of the plant chassis is standing on the ground adjacent thereto. In the raised lifting position, the end of the plant chassis is lifted off the ground and is supported by the support and guide surface of the lifting cradle.