CONDITIONS FOR SAFETY OPERATION AND MANEUVERABILITY OF LOW-TONNAGE ROADTRAIN AT CRITICAL RATES OF MOTION

The paper deals with the control device for a uniaxial trailer, which makes it possible to increase the maneuverability and reliability of  the movement of a low-tonnage roadtrain by using flexible coupling  in the hitch mechanism. This makes it possible to use roadtrain at  emergency situations, in narrow urban streets, in greenhouses,  livestock houses, and  warehouses. This mechanism is simplicity,  reliability and high maintainability, which allow to operate it when  transporting non-bump-resistant cargo of different purpose. An  application for an invention was filed with the proposed mechanism. The maximum forces in the cable, the drawbar hook and the  controlled elements of the coupling were calculated in case of emergency braking with the maximum loading of the trailer in  difficult road conditions. Critical turn radii were determined at different speeds and tire-to-surface friction coefficients. A mathematical simulation of the movement of the roadtrain was  performed. The device was installed and tested on the basis of the  road laboratory KP-514MP based on the car Gazel 2705 with trailer  IAPZ-739. Full-scale tests were carried out in various urban and field conditions with different loading of the trailer and shifts of the cargo mass center. The cable installation in the hitch significantly changes the geometry of the movement when reversing and emergency  braking. Also the jack-knifing of the roadtrain is obviated, while  without a cable, there is almost always a threat of suchjack-knifing, which is highly undesirable in the transport of non-bumpresistant cargoes. This significantly affects the active safety of the low- tonnage roadtrain, determines its braking efficiency and transverse  stability of the links during the movement. A mathematical model  that had been tested experimentally was described, which makes it  possible to estimate the critical turn radii during maneuvering, the  conditions for emergency braking and the possibility of reversing motion. Two types of cables can be used in the flexible hitch-coupling: one is with a diameter of 9 mm and has the metallic core,  another is LX-0, it consists of 46 wires with the organic core. Also  other types of cables can be applicated if they withstand load of 4.5-5.0 t.

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