A modular low- bed semi-trailer for transportation of machines and other heavy and big loads

The paper presents the assumptions made and solutions used in a newly designed low-bed semi-trailer for the transportation of heavy and oversized loads, especially heavy self-propelled road machinery. During the design phase, special attention was paid to the versatility of the semi-trailer. The semi-trailer consists of 4 main modules: a hydraulic removable gooseneck allowing for coupling the semi-trailer to a tractor unit, an extendable low bed, a 2- axle bogie and a 3-axle bogie. The modules can be combined in different ways to create different configurations of the semi-trailer. Owing to that, the carrying capacity of the semi-trailer can be easily matched to the equipment carried. Depending on the current needs, the semi-trailer can have 2, 3 or 5 axles, a payload from 28 to 65 tons, and a length from 13.2 to 20.1 m. Wheeled and caterpillar vehicles can drive onto the lowbed from the front, after the gooseneck has been detached. The length and width of the bed can be adjusted within the range of 2 and 0.6 m, respectively. An important advantage of this semi-trailer is the fact that in a 2-axle configuration it meets the regulations for standard trailers and can be driven in public roads and carry normal loads without a special permission. Thanks to the fact that all its wheels are steered and controlled by a hydraulic steering system, the semi-trailer has very good manoeuvrability despite its long length. The semi-trailer meets rigorous safety demands – it is equipped with a braking system with ABS/EBS, an advanced load fixing system, marking and lighting systems and others. Research and development experiments performed during the design process, among others those concerning the steering system and optimization of the supporting structure of the semi-trailer using FEM analysis, are characterized in this paper.