Design of a frame to a semi low-loader

The paper presents the process of design of a frame for a semi low loader for the transportation of oversize loads, especially wheeled and tracked machines. After considering different solutions of a frame, a central beam was chosen and an initial design was developed. The initial model of the frame was analyzed with the use of FEM and was then modified. Two final versions of the frame were prepared. One of them was used in a 4 axle trailer with a load deck that can be extended in length and width to carry oversize and heavy loads. An important advantage of the trailer is its versatility and the fact that in a non-extended state it meets the regulations for standard trailers and can carry loads without a special permission. The paper focuses on the application of FEM analysis in the design of the part of the beam where highest stresses were located. A design solution for a ladder frame, a schematic image of a box-type central beam, a design solution for rear ramps, geometrical models of semitrailer frame with boundary conditions, stress distributions in a non-extended and extended frame model, a section of the rear part of the frame with sliding plates visible and a pin guide bar for blocking frame extension, stress distribution in the front part of the frame, single and double supporting rib, side wall supporting plate and stress distribution after the use of plates and one supporting rib, stress distribution after the employment of plates and two supporting ribs, stress distribution in the alternative gooseneck design, main dimensions of the semitrailer, extended semitrailer are presented in the paper.