Abstract:
Heavy vehicles are made specially to work on uneven road surfaces and they contain some attachment that to be used for such soil and are used upon wheeled or trucked systems, this attachment is used to help generate very high torque of pulling to be used for all types of soils. These vehicles are different in designs, shapes, establishments, capabilities and attachments.The transmission system of the vehicle consists of several components which sometimes encounter unfortunate failures, some of these failures maybe caused by the manufacturer and design faults, material faults, maintenance faults as well as user originated faults. In the heavy vehicle under study which consists of four driving axles, the transfer gear box of the vehicle is used for transmitting power to appropriate axles two, three or four axles. The two front axles can be engaged when needed through a cluster gear which is mounted in the primary shaft of the transfer gear box. The cluster gear of the transfer gear box breaks very frequently, which result in a low reliable performance of the vehicle. Reliability is a major importance for this heavy vehicle.In this research,a modification of the transfer gear box which includes two additional clutches to smooth the engagement of the cluster gear is presented. The clutches were designed to carry a torque of 1852 Nm. The friction surfaces which are made of carbon graphite are of diameter 260 mm outer and 160 mm inner diameter.
