The world premiere of an independent wheel suspension for semitrailers made news at the European Road Transport Show in Amsterdam. The goal is weight reduction, as well as a better ride and stability.
Weight was reduced in two ways on the Stokota-Ekw platform trailer shown at the RAI in Amsterdam. The first way was moving the mainframe beams to the sides, thus replacing the side rails. This has the added benefit of providing a wider base for the movable crane, because the crane carriage wheels ride on the side mainframe beams.
Secondly, the three rigid axles were replaced with independently air suspended wheels. The rear two wheels on each side are steered hydraulically to provide better maneuverability for the 45-ft semitrailer, and the front wheels are liftable. Kingpin steering allows the force-steered wheels to turn 42 degrees.
Tony Geusens, the engineer who designed the show trailer for Stokota, had many years experience designing trailers, liquid tankers, dry bulkers, and touring buses for his father's former firm (LAG-Trailer) in Belgium. Tag axles on buses often have independent wheel suspensions. The new trailer independent suspension builds on the same principle of a stub axle connected to the chassis by means of triangular support arms.
Independent wheel suspensions often are used on straddle trailers for glass transport and low-floor trailers. However, these constructions have heavy wheel houses that absorb all the forces. In the Geusens lightweight design, the triangular supporting arms are attached to a lightweight subframe. This construction also allows lowering the center of gravity of some cargo bodies by nesting the body between the perimeter frame rails.
In the Geusens design, the frame rails are extra deep at the high-stress area between support legs and the rear wheels. This deep frame reduces the need for side underrun protection, and also opens up compartments for pallet storage, spare tires, or tools.
Total weight reduction of the Stokota 45-ft platform with perimeter frame and independent suspension on all six wheels was 1,100 kg (2,425 lb).
Geusens is an independent consultant and is engineering this design for other trailer manufacturers as well, for use with petroleum tankers, dry bulk tipping trailers, and refrigerated trailers (TG Consulting BVBA, Luytenstraat 58, B-3960 Bree, Belgium). Stokota NV, Dijkstraat 23, B-9160 Lokeren, Belgium.