Driven by changes in the agricultural sector during the last decade, the transport rate and the maximum speed of high power agricultural tractors are increasing. Another trend is the increasing equipment rate of tractors with full power-shift or CVT (continuously variable transmissions). Both transmission types provide the capability to reduce the speed of an agricultural tractor-trailer combination with high deceleration rates without using the service brakes of either the tractor or the trailer(s). In certain conditions, these high deceleration rates via the tractor drive train cause hazardous situations such as unstable tractor-trailer combinations or even lead to jackknifing. Two systems which improve driving stability of tractor-trailer combinations substantially by detecting critical driving manoeuvres will be presented, in both cases the trailer will be actively braked resulting in a stable tractor-trailer combination. The article concludes with a visualization of the advantages and performance of both systems. High deceleration rates of tractor drive trains are responsible for pushing forces up to 30 kN in the coupling point. To avoid hazardous situations or even jackknifing, the trailer has to braked actively. A system called ITC (Intelligent Trailer Control), integrated in the tractor, is able to sense unstable driving situations and to react with active trailer brake interventions. Adapted to the driving situation, the trailer brakes are either activated by a pulsed or a continuous pressure. To prevent rollovers of agricultural trailers with a high centre of gravity, a stand-alone RSP (Roll Stability Program) system for agricultural trailers is presented. The system is completely integrated in the TEBS G2 module of Knorr-Bremse. By monitoring lateral acceleration, load and speed, the system is able to determine unstable conditions and applies the trailer brakes automatically.
Improved driving stability of an agricultural tractor-trailer combination
2011
8 Seiten, 6 Bilder, 3 Quellen
Conference paper
English
The braking of agricultural tractor/trailer combination
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