tailieunhanh - Advanced Vehicle Technology 2 Episode 2

Tham khảo tài liệu 'advanced vehicle technology 2 episode 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Fig. Ball and socket caravan trailer towing attachment the tractor unit just sufficiently back to clear the rear tractor road wheels when the trailer is coupled and the combination is being manoeuvred Fig. a . To provide additional support for the legs bracing stays are attached between the legs and from the legs diagonally to the chassis crossmember Fig. b . The legs consist of inner and outer high tensile steel tubes of square section. A jackscrew with a bevel wheel attached at its top end supported by the outer leg horizontal plate in a bronze bush bearing. The jawscrew fits into a nut which is mounted at the top of the inner leg and a taper roller bearing race is placed underneath the outer leg horizontal support plate and the upper part of the jackscrew to minimize friction when the screw is rotated Fig. b . The bottom ends of the inner legs may support either twin wheels which enable the trailer to be manoeuvred or simply flat feet. The latter are able to spread the load and so permit greater load capacity. To extend or retract the inner legs a winding handle is attached to either the low or high speed shaft protruding from the side of the gearbox. The upper high speed shaft supports a bevel pinion which meshes with a vertically mounted bevel wheel forming part of the jackscrew. Rotating the upper shaft imparts motion directly to the jackscrew through the bevel gears. If greater leverage is required to raise or lower the front of the trailer the lower shaft is engaged and rotated. This provides a gear reduction through a compound gear train to the upper shaft which then drives the bevel pinion and wheel and hence the jackscrew. Automatic chassis lubrication system The need for automatic lubrication system Fig. Owing to the heavy loads they carry commercial vehicles still prefer to use metal to metal joints which are externally lubricated. Such joints are kingpins and bushes shackle pins and bushes steering ball joints fifth