1、BRITISH STANDARD BS 3170:1972 Specification for Flexible couplings for power transmissionBS3170:1972 This British Standard, having been approved by the Mechanical Engineering Industry Standards Committee, was published under the authority of the Executive Board on 30 March 1972 BSI 08-1999 First pub
2、lished November 1959 First revision March 1972 The following BSI references relate to the work on this standard: Committee reference MEE/36 Draft for comment 70/35265 ISBN 580 07440 4 Co-operating organizations The Mechanical Engineering Industry Standards Committee, under whose supervision this Bri
3、tish Standard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: The scientific and industrial organizations marked with an asterisk in the above list, together with the following, were directly represented on the committe
4、e entrusted with the preparation of this British Standard. Associated Offices Technical Committee Engineering Equipment Users Association* Association of Consulting Engineers Gas Council Association of Hydraulic Equipment Institution of Civil Engineers Manufacturers Ltd. Institution of Gas Engineers
5、 Association of Mining Electrical and Institution of Heating and Ventilating Mechanical Engineers Engineers British Chemical Plant Manufacturers Institution of Mechanical Engineers Association Institution of Mechanical Engineers British Compressed Air Society (Automobile Division) British Electrical
6、 and Allied Manufacturers Institution of Plant Engineers Association Institution of Production Engineers British Gear Manufacturers Association* Locomotive and Allied Manufacturers British Internal Combustion Engine Association of Great Britain Manufacturers Association London Transport Executive Br
7、itish Mechanical Engineering Machine Tool Trades Association Confederation* Ministry of Defence British Pump Manufacturers Association* Ministry of Defence, Army Department British Steel Industry* National Coal Board Crown Agents for Oversea Governments and National Physical Laboratory (Department o
8、f Administrations Trade and Industry) Department of Employment and Productivity Royal Institute of British Architects (H.M. Factory Inspectorate) Telecommunications Engineering Department of the Environment Manufacturing Association Department of Trade and Industry Water Tube Boilermakers Associatio
9、n Department of Trade and Industry National Engineering Laboratory Electricity Council, the Central Electricity Generating Board and the Area Boards in England and Wales Association of British Correspondence Colleges Institute of Marine Engineers Council of British Manufacturers of Petroleum Equipme
10、nt Amendments issued since publication Amd. No. Date CommentsBS3170:1972 BSI 08-1999 i Contents Page Co-operating organizations Inside front cover Foreword ii 1 Scope 1 2 Definitions 1 3 Performance under operating conditions 3 4 Specification of operating conditions 3 5 Balancing of couplings 4 6 A
11、lignment of driving and driven shafts 4 7 Dimensions of bores, limits and fits 4 8 Components 4 9 Marking for assembly 4 10 Guarding 4 Appendix A Notes on methods of checking angular and parallel alignmentofcouplings 5 Figure 1 Displacement forces 2 Figure 2 Method of checking angular and parallel m
12、isalignment 6BS3170:1972 ii BSI 08-1999 Foreword This standard makes reference to the following British Standards and Code of Practice. BS 1649, Guards for shaft couplings. BS 3692, ISO metric precision hexagon bolts, screws and nuts. BS 3763, The International System of units (SI). BS 4168, Hexagon
13、 socket screws and wrench keys metric series. BS 4183, Machine screws and machine screw nuts metric series. BS 4235, Metric keys and keyways Part 1: Parallel and taper keys. BS 4320, Metal washers for general engineering purposes. BS 4464, Spring washers for general engineering and automobile purpos
14、es (metricseries). BS 4500, ISO limits and fits. BS 4506, Shaft ends. BS . . . ., Shaft fitment bores 1) . CP 3004, Guarding of machinery. The first edition of this standard published in 1959 entitled “Characteristics of flexible couplings for power transmission” was prepared under the authority of
15、the Mechanical Engineering Industry Standards Committee and related to mechanical devices for flexibly coupling a driving to a driven shaft other than those devices properly referred to as flexible shafts or universal joints. The purpose of this standard, which is prepared under the same authority,
16、is to bring together, under a more appropriate title, information of assistance to those engaged in choosing couplings. It is not the intention to establish a dimensional standard for flexible shaft couplings. The following related standard has also been published: BS 3092, Dimensions of main fricti
17、on clutches, main power-take-off assemblies and associated attachments for i.c. engines. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of
18、 itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to6 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendm
19、ent table on the inside front cover. 1) In course of preparation.BS3170:1972 BSI 08-1999 1 1 Scope This British Standard specifies some of the requirements for flexible couplings for power transmission and includes definitions; performance under operating conditions; dimensions of bores; references
20、to necessary components, such as bolts, screws, keys and guarding. An appendix on alignment is included. This standard does not apply to flexible shafts or universal joints. NOTEThe titles of the British Standards referred to in this standard are listed on page ii. 2 Definitions For the purposes of
21、this British Standard, the following definitions apply. 2.1 rigid coupling a device for connecting a driving to a driven shaft in such a manner that no displacement of the one relative to the other can occur, the two shafts behaving as one 2.2 flexible coupling a flexible coupling, as distinct from
22、a rigid coupling, possesses to a greater or lesser extent the ability to permit relative displacement of the driving and driven shafts in one or a combination of the forms illustrated inFigure 1 (information on particular types of flexible couplings can be obtained from individual manufacturers) 2.3
23、 Misalignment The condition in which the axes of the driving and driven shafts are not truly in line. Misalignment may be: 2.3.1 angular angular misalignment is present when the shaft axes are inclined one to the other. Its magnitude is stated as the inclination of the shaft axes, measured at the co
24、upling faces, in radians, in degrees, or in length units per unit length Figure 1a(i) and Figure 1a(ii) 2.3.2 parallel parallel misalignment is present when the axes of the driving and driven shafts are parallel but are laterally displaced. Its magnitude is stated in length units (Figure 1b) NOTEIn
25、practice misalignment of both angular and parallel forms can occur together. 2.4 End float The ability to accommodate relative axial displacement (f) of the connected shafts (Figure 1c). It may result from the deformation of resilient materials, from the sliding of co-operating surfaces, or from a c
26、ombination of the two. In coupling dimensional drawings the end float is often the sum of two separate dimensions. The end float is stated in length units. 2.4.1 limited end float for some special applications in which the shaft of one machine, either driving or driven, is to be effectively axially
27、located by the shaft system of the other machine a limitation of the coupling end float is necessary. This limitation may be inherent in the design or by mechanical stops. Such a coupling is described as a limited end float coupling 2.5 Torsional flexibility The ability of a coupling to twist elasti
28、cally under torque. It is stated as the angular displacement (radians or degrees) produced by unit torque: it is usually small and is frequently expressed as micro-radians, or micro-degrees, per unit of torque(Figure 1d). 2.5.1 torsional stiffness the resistance to twisting of a coupling under torqu
29、e. It is the reciprocal of the torsional flexibility and is expressed as torque per unit angular displacement (radians or degrees) 2.5.2 torsional resilience the ability of a coupling to absorb and restore energy expressed in energy units,i.e. joules 2.5.3 torsional backlash free angular displacemen
30、t. It is stated in radians or degrees NOTE 1Alternative expressions for 2.5.1 are “torsional rigidity” and “torsional spring rate”. NOTE 2Depending on the type of coupling, 2.5 and 2.5.1 may be constant or may vary with increasing displacement. NOTE 3A torsionally flexible coupling may be used to mo
31、dify the torsional vibration characteristics of a shaft system and also to absorb energy due to torsional shock.BS3170:1972 2 BSI 08-1999 (i) Symmetrical (A = B) (ii)Non-symmetrical(A/B) Figure 1a Angular misalignment Figure 1b Parallel misalignment Figure 1c End float Figure 1d Torsional flexibilit
32、y Figure 1 Displacement forcesBS3170:1972 BSI 08-1999 3 2.6 radial load carrying ability radial load carrying ability is the property required of a coupling that is to support one end of a shaft which is at its other end supported by a similar coupling or a bearing. The coupling then sustains a prop
33、ortion of the shaft weight 3 Performance under operating conditions Displacements (angular, parallel, axial or torsional) in a flexible coupling are associated with forces external to the coupling. Bending stresses in shafts and radial loads on bearings result from angular and parallel displacements
34、 of the coupling halves. The significance of these effects produced in the coupled machines is dependent on the magnitude of the displacement, the transmitted torque, the speed, and the design of the coupling employed. Axial loads on bearings result from axial displacement of the coupling halves and
35、 may be transient(e.g. during the sliding of interacting surfaces) or permanent(e.g. when there is elastic deformation). The torsional displacement between the coupled shafts results from the transmitted torque and has a magnitude dependent on the torque and the coupling design,e.g. relatively large
36、 when rubber or some similar substance is employed as the elastic medium, relatively small when steel is so employed. 3.1 Displacement forces. The following may require consideration at the design stage and may be used as an indication of the limits of performance of a particular coupling. 1) Angula
37、r. The force resisting angular misalignment shall be stated as the bending moment about the effective centre of resistance of the coupling or about the point of intersection of the shaft axes and shall be quoted in force-length units,i.e. newton metres. 2) Parallel. The force resisting parallel misa
38、lignment is a radial force acting in line with the displacement and shall be quoted in force units, i.e. newtons. 3) End float (axial). The force resisting end float is a force acting in the direction of axial displacement and shall be quoted in force units,i.e. newtons. 4) Torsional. The force resi
39、sting torsional displacement is a twisting moment about the shaft axis and shall be quoted in force-length units,i.e. newton metres. The displacement forces may or may not be related directly to the magnitude of the displacement and when required to be specified they shall be associated with specifi
40、c values of displacement, torque and speed. Within a specified and usually narrow range of operating conditions these displacement forces may often be quoted as a force per unit displacement. 4 Specification of operating conditions It is recommended that the following particulars should be given to
41、the coupling manufacturer or supplier for all applications. SI units should be utilized where applicable (see BS3763). 4.1 Description of machines 1) Driving. 2) Driven. 3) Any associated transmission equipment. 4.2 Nature of duty 1) Continuous. 2) Intermittent (duty cycle). 3) Shock conditions. 4)
42、Fluctuating or reversing conditions. 4.3 Power to be transmitted 1) Normal. 2) Maximum. 4.4 Speed of the shafts to be connected 1) At which normal power is transmitted. 2) At which maximum power is transmitted. 3) Maximum speed. 4.5 Dimensions of the shafts to be connected 1) Actual diameters or nom
43、inal diameters with limits. 2) Length of shaft ends. 3) Keyway details (type, number dimensions, etc.). Alternatively, the finished bore diameters and keyways required in the coupling halves may be specified. The bores of the coupling halves may, as supplied, be required to be rough machined or fini
44、sh machined. The above information will suffice for the majority of applications where the shafts are nominally horizontal and in good alignment (seeAppendix A). Where specific displacements must be accommodated these shall be stated using the definitions in2 and the magnitudes shall be given. NOTEI
45、t is customary for coupling manufacturers to give, in their technical literature, service factors applicable to their own products. The particulars quoted above are to be taken into consideration in the selection of a factor.BS3170:1972 4 BSI 08-1999 4.6 Additional information. It is recommended tha
46、t the following additional information should be supplied when applicable: 1) Position of shafts to be connected (vertical, inclined, etc.). 2) Details of limitations in the space available for assembling and dismantling the coupling. 3) Details, including ratio, of any gearing on either of the shaf
47、ts to be connected. 4) Inertia of rotating parts of the shaft system, such as flywheels. 5) If subject to braking forces, the time to come to rest. 6) Details of peak torques (driving, braking or shock). 7) Range of temperature conditions, atmospheric conditions, any other special conditions. 8) Pos
48、ition, number and size of any holes required for draw-off bolts or jacking-screws. 9) Dimensions of any recess in the face of a half coupling required for a retaining screw, nut or ring. 10) Position and size of any set screw required in the boss over the keyway(s). 11) Any other requirements. 5 Bal
49、ancing of couplings The inherent standard of balance of most types of flexible coupling is generally acceptable. When special attention to the balance of the combined equipment is required full particulars of the application should be given to the manufacturer or supplier of the coupling and there should be mutual agreement about the action to be taken. 6 Alignment of driving and driven shafts Notes on the alignment of driving and driven shafts are given inAppendix A. Permissible errors in initial alignment shall be agreed between the purchaser and
