• The tractor-semitrailer combinations are  becoming larger and longer, face the problem of off  tracking, which is the ensuing difference in path  radii between the front & rear axles as it  manoeuvres a turn.
• Despite steering the rear axle of the semitrailer, a  way of mitigating off-tracking is to shift the fifth  wheel coupling rearwards. But, it is limited by the  distribution of the semitrailer’s load; any rearward  shift of the fifth wheel coupling results in reduction of  the total static load on prime mover’s front axle  and available traction, leading to directional  instability of the vehicle.

The aforesaid issues are eased with a mechanism to  reduce off tracking without affecting the load  distribution among the axles of the tractor.

The Present Patent discloses a fifth wheel coupling mechanism for coupling a prime mover and a semitrailer comprising of a roller mechanism and a cylindrical joint. The method for above mentioned subject matter comprising:

• A roller mechanism and a cylindrical joint on either side of the rear axle of the prime mover.
• Roller mechanism comprising plurality of rollers rotatable around their axis, fixed to chassis of prime mover, a track fixed beneath chassis of semitrailer, where rollers roll on track disposed above while articulating.
• The cylindrical joint comprises of a kingpin, a cylindrical mating part adapted to engageably receive the kingpin, guide plate to guide the kingpin, a locking mechanism to lock kingpin in position.