车辆工程外文翻译----传输方式和操作.docx

附录2英文翻译TRANSMISSION TYPES AND OPERATIONTravel-speed-changing systems found in tractors vary considerably particularly with respect to the number of speeds, kinds of gears, and methods of shifting. Based on these factors, transmission types can be classified as (1) sliding spur gear, (2) constant-mesh with shifting collars, (3) Synchromesh, and (4) hydrostatic. Also with respect to changing speeds, it can be done manually with a hand-lever or automatically by hydraulic pressure. These variations will be explained in connection with the descriptions of different makes of tractor transmissions. In general, the smaller sizes of tractors, 20 to 40 PTO hp use simpler transmissions with fewer travel speeds, while the larger sizes have speeds ranging from six or eight to twelve or sixteen. In such cases, provision is made for shifting from the low-range to the high-range speeds or vice versa while the tractor is in motion, and without disengaging the master clutch and coming to a dead stop. These advantages, in turn, permit a closer and more convenient adjustment and a quicker response of power, torque, and tractive ability of the tractor to the specific drawbar-load conditions and requirements.Plain Spur-Gear Transmission Figure 18-7 illustrates the design and operation of the type of transmission originally used in earlier tractors and still used in some small, current models. As shown, the different speeds are obtained by sliding gears of a certain size into me h with others of another size. Reverse requires an additional single gear on a separate short shaft. The entire mechanism operates in an oil bath in a special housing. The bearings may be plain or antifriction type. The different speeds are obtained by a manually operated lever attached to certain gears in such a manner as to slide them into mesh with others that are stationary. These changes can only be made with the main clutch disengaged and the tractor stationary. Figure 18-8 shows a similar transmission used