【正文】 it is almost always necessary to calculate them so that he knows they are within acceptable limits. Whenever possible, the powertransmission elements, such as gears or pullets, should be located close to the supporting bearings, This reduces the bending moment, and hence the deflection and bending stress.Although the von MisesHenckyGoodman method is difficult to use in design of shaft, it probably es closest to predicting actual failure. Thus it is a good way of checking a shaft that has already been designed or of discovering why a particular shaft has failed in service. Furthermore, there are a considerable number of shaftdesign problems in which the dimension are pretty well limited by other considerations, such as rigidity, and it is only necessary for the designer to discover something about the fillet sizes, heattreatment, and surface finish and whether or not shot penning is necessary in order to achieve the required life and reliability.Because of the similarity of their functions, clutches and brakes are treated together. In a simplified dynamic representation of a friction clutch, or brake, two inertias I1 and I2 traveling at the respective angular velocities W1 and W2, one of which may be zero in the case of brake, are to be brought to the same speed by engaging the clutch or brake.
Slippage occurs because the two elements are running at different speeds and energy is dissipated during actuation, resulting in a temperature rise. In。 that is ,a righthand driver goes with a righthand driven. In the design of crossedhelical gears, the minimum sliding velocity is obtained when the helix angle are equal. However, when the helix angles are not equal, the gear with the larger helix angle should be used as the driver if both gears have the same hand. Worm gears are similar to crossed helical gears. The pinion or worm has a small number of teeth, usually one to four, and since they pletely wrap around the pitch cylinder they are called threads. Its mating gear is called a worm gear, which is not a true helical gear. A worm and worm gear are used to provide a high angularvelocity reduction between nonintersecting shafts which are usually at right angle. The worm gear is not a helical gear because its face is made concave to fit the curvature of the worm in order to provide line contact instead of point contact. However, a disadvantage of worm gearing is the high sliding velocities across the teeth, the same as with crossed helical gears.Worm gearing are either single or double enveloping. A singleenveloping gearing is one in which the gear wraps around or partially encloses the worm.. A gearing in which each element partially encloses the other is, of course, a doubleenveloping worm gearing. The important difference between the two is that area contact exists between the teeth of doubleenveloping gears while only line contact between those of singleenveloping gears. The worm and worm gear of a set have the same hand of helix as for crossed helical gears, but the helix angles are usually quite different. The helix angle on the worm is generally quite large, and that on the gear very small. Because of this, it is usual to specify the lead angle on the worm, which is the plement of the worm helix angle, and the helix angle on the gear。 ShaftIn the force analysis of spur gears, the forces are assumed to act in a single plane. We shall study gears in which the forces have three dimensions. The reason for this, in the case of helical gears, is that the teeth are not parallel to the axis of rotation. And in the case of bevel gears, the rotational axes are not parallel to each other. There are also other reasons, as we shall learn.Helical gears are used to transmit motion between parallel shafts. The helix angle is the same on each gear, but one gear must have a righthand helix and the other a lefthand helix. The shape of the tooth is an in volute helicoids. If a piece of paper cut in the shape of a parallelogram is wrapped around a cylinder, the angular edge of the paper bees a helix. If we unwind this paper, each point on the angular edge generates an in volute curve. The surface obtained when every point on the edge generates an in volute is called an in volute helicoids.The initial contact of spurgear teeth is a line extending all the way across the face of the tooth. The initial contact of helical gear teeth is a point, which changes into a line as the teeth e into more engagement. In spur gears the line of contact is parallel to the axis of the rotation。第 50 頁 共 50 頁附錄1 GEAR AND SHAFT INTRODUCTIONAbstract: The important position of the wheel gear and shaft can39。每當我遇到問題時，他們總是耐心幫助我解決。他們始終是我堅強的依靠和最后的港灣，我將會加倍努力工作來回報父母的恩情。在我走過的那些日子里，父母一直在背后默默的支持我，在我遇到困難時不斷鼓勵我，對我作出的任何選擇總是給予理解和支持。首先我要感謝楊漠漠老師，本設(shè)計是在楊漠漠的悉心指導下完成的，在整個論文工作中，老師都給予了全面、認真的指導。參考文獻[1] 嚴大考, [M]. 鄭州:鄭州大學出版社, 2003. [2] 九省二區(qū)第三屆泛珠三角先進制造論壇論文集[C]. 天津: [出版社不祥],2006.[3] 須雷. 現(xiàn)代起重機的特征和發(fā)展趨向[J]. 起重運輸機械, 1997(10):36.[4] 李學濤. 東風汽車公司開展物流工作的回顧和今后工作的展望報告[J], 1996(5):34.[5] 羅婉霞. 國外起重機制造業(yè)的發(fā)展趨勢及中國起重機制造業(yè)的現(xiàn)狀[J]. 機械開發(fā), 1999(2):47.[6] Deepak Khemani, Radhika B,Selvamani,Ananda Rabi Dhar, et al, CBR in Fused CastRefractory Manufacture,S. Crawa ndA Yreece:ECCBR,2002,LN AI24 16:560574.[7] L athamR S e tal .Co nnectivitya nalysis::toolfo rpor cessingg eometricc ided Design, 1996, 28{11):917928.[8] Building a Windows XP Embedded Device / embedded / xp / getstart / tutorials / .[9] 陳道南, 盛漢中主編. 起重機課程設(shè)計[M]. 北京:冶金工業(yè)出版社, 1983. [10] 王金諾, 虞和謙, 張質(zhì)文等. 起重機設(shè)計手冊[M]. 北京: 中國鐵道出版社, 2001.[11] 楊朝祿, 起重機用鋼絲繩的失效[J]. 建筑安全, 2004(5):36．[12] 王強. 起重機用鋼絲繩的損傷形式及防治措施[J]. 港口裝卸, 2007(3):24．[13] 孫曄. 起重機用鋼絲繩使用壽命的探討[J]機務(wù)管理. 2008(9):35.[14] 楊嘉煒. 起重機常見機械故障分析及預防措施[J]. 上海, 2004(1):46.[15] 胡宗武, 顧迪民. 起重機設(shè)計計算[M]. 北京: 北京科技出版社, 1998.[17] 費舍爾等. 起重運輸機械設(shè)計基礎(chǔ). 范祖堯等譯[M]. 北京: 機械工業(yè)出版社, 1991.[18] 鄭江, 許瑛. 機械設(shè)計[M]. 北京: 中國林業(yè)出版社, 北京大學出版社, 2006.[19] 顧迪民. 工程起重機[M]. 北京: 中國建筑工業(yè)出版社, 1988.[20] 黃