METHOD OF RELEASABLY COUPLING ARTICULATED VEHICLES AND PREVENTING JACK-KNIFING

摘要

This invention relates to an improved coupling for articulated vehicles that reduces or prevents jack-knifing of such vehicles when braking hard or on slippery surfaces. Jack-knifing usually occurs where all four wheels of the tractor portion of the vehicle lose traction and the whole vehicle skids in a straight line until any slight imbalance in the rolling resistance of the wheels imparts a force to the tractor or trailer having a component normal to the direction of travel causing the vehicle to swing about the point of coupling between the two units into the fully jackknifed position. Jack-knifing can also occur where the rear wheels of the tractor portion of the vehicle lose traction. Any force normal to the direction of travel will in this case cause sudden and serious jack-knifing that is very difficult if not impossible to correct. The invention comprises a simple releasable coupling between the tractor and trailer of an articulated vehicle which allows articulation of the vehicle but incorporates a braking system that can prevent or inhibit rotation about the point of coupling between the tractor and trailer in circumstances likely to produce jack-knifing. The braking system of the coupling may be connected to the braking system of the articulated vehicle so that when the braking system of the articulated vehicle is operated the braking system of the coupling is also operated and prevents or inhibits any further jackknifing of the articulated vehicle. Two pairs of locating members locate the trailer with respect to the tractor and are arranged so as to provide reactive moments of force that oppose any tendency of the trailer to overturn when cornering or travelling on uneven roads.