外文翻譯--齒輪和齒輪傳動-其他專業(yè)-展示頁
2025-01-31 00:34本頁面
【正文】 ion of power losses in the gears, in bearings, and from windage and churning of lubricant.) Speed: In a given gear normally limited to some specific pitchline velocity. Speed capabilities can be increased by improving accuracy of the gear teeth and by improving balance of the rotating parts. Power: Load and speed capacity is determined by gear dimensions and by type of gear. Helical and helicaltype gears have the greatest capacity (to approximately 30,000 hp). Spiral bevel gear are normally limited to 5,000 hp, and worm gears are usually limited to about 750 hp. Special requirements MatchedSet Gearing: In applications requiring extremely high accuracy, it may be 蘭州交通大學(xué)畢業(yè)設(shè)計(jì)（論文） 3 necessary to match pinion and gear profiles and leads so that mismatch does not exceed the tolerance on profile or lead for the intended application. Tooth Spacing: Some gears require high accuracy in the circular of teeth. Thus, specification of pitch may be required in addition to an accuracy class specification. Backlash: The AMGA standards remend backlash ranges to provide proper running clearances for mating gears. An overly tight mesh may produce overload. However, zero backlash is required in some applications. Quiet Gears: To make gears as quit as possible, specify the finest pitch allowable for load conditions. (In some instances, however, pitch is coarsened to change mesh frequency to produce a more pleasant, lowerpitch sound.) Use a low pressure angle. Use a modified profile to include root and tip relief. Allow enough backlash. Use high quality numbers. Specify a surface finish of 20 ? in. or better. Balance the gear set. Use a nonintegral ratio so that the same teeth do not repeatedly engage if both gear and pinion are hardened steel. (If the gear is made of a soft material, an integral ratio allows the gear to coldwork and conform to the pinion, thereby promoting quiet operation.) Make sure critical are at least 20% apart from operating speeding or speed multiples and from frequency of tooth mesh. Multiple mesh gear Multiple mesh refers to move than one pair of gear operating in a train. Can be on parallel or nonparallel axes and on intersection or nonintersecting shafts. They permit higer speed ratios than are feasible with a single pair of gears . Series trains:Overall ratio is input shaft speed divided by output speed ,also the product of individual ratios at each mesh ,except in plaary gears .Ratio is most easily found by dividing the product of numbers of teeth of driven gears by the product of numbers of teeth of driving gears. Speed increasers (with stepup rather than stepdown ratios) may require special care in manufacturing and design. They often involve high speeds and may creste problems in gea
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