THE BRAKING PERFORMANCE OF AGRICULTURAL VEHICLES

摘要

The dynamics of braking of agricultural tractor-trailer combinations was analysed and equations established for calculation of deceleration, over-run force and axle loads for four-wheel balanced trailers and single-axle unbalanced trailers, with and without different types of braking systems and with two and four-wheel brakes on the tractor. Without brakes on the trailer, a much higher deceleration could be achieved with an unbalanced than a balanced trailer, using tractor brakes only. This remained true when brakes were added to the trailer, unless they were powerful enough to lock the trailer wheels, when decelerations were almost equal. Over-run forces, however, were also much higher with the unbalanced trailer and this led to instability, particularly on slippery surfaces, where the tractor rear wheels could easily be locked. The situation was similar with four-wheel brakes on the tractor, except that decelerations were greater and front axle loads could be very high.