1、BRITISH STANDARD BS 6347-6: 1983 ISO 789-6: 1982 Incorporating Amendment No. 1 Performance assessment of agricultural tractors Part 6: Method for determination of centre of gravity ICS 65.060.10BS6347-6:1983 This British Standard, having been prepared under the directionof the Agricultural Machinery
2、 and Implements Standards Committee, was published under the authority ofthe Board of BSI and comes intoeffect on 29July1983 BSI 03-2000 ISBN 0 580 13364 8 Committees responsible for this British Standard This British Standard was published under the direction of the Agricultural Machinery and Imple
3、ments Standards Committee AGE/-. Its preparation was entrusted to Technical Committee AGE/6 upon which the following bodies were represented: Agricultural Engineers Association British Agricultural and Garden Machinery Association Ltd. County Surveyors Society Department of Industry (Mechanical Engi
4、neering) Forestry Commission Health and Safety Executive Home Timber Merchants Association of Scotland Ministry of Agriculture, Fisheries and Food National Farmers Union National Institute of Agricultural Engineering National Union of Agricultural and Allied Workers Society of Motor Manufacturers an
5、d Traders Limited Coopted members Amendments issued since publication Amd. No. Date of issue Comments 9584 August 1997 Indicated by a sideline in the marginBS6347-6:1983 BSI 03-2000 i Contents Page Committees responsible Inside front cover National foreword ii 0 Introduction 1 1 Scope and field of a
6、pplication 1 2 Reference 1 3 Definitions 1 4 Apparatus 1 5 General requirements 2 6 Procedure 2 7 Test report 3 Annex Specimen test report 7 Figure 1 Determination of horizontal fore-and-aft coordinate 4 Figure 2 Determination of vertical coordinate 5 Figure 3 Determination of lateral coordinate in
7、the horizontal plane 6 Publications referred to Inside back cover x () h () y ()BS6347-6:1983 ii BSI 03-2000 National foreword This Part of BS 6347 has been prepared under the direction of the Agricultural Machinery and Implements Standards Committee. It is identical with ISO789-6 “Agricultural trac
8、tors Test procedures Part 6: Centre of gravity”, which was developed by Technical Committee ISO/TC23, Tractors and machinery for agriculture and forestry, and was published in1982 by the International Organization for Standardization (ISO). It includes amendment1 to International Standard ISO789-6:1
9、982 prepared by Technical Committee ISO/TC23, Tractors and machinery for agriculture and forestry, Subcommittee SC2, Common tests. Terminology and conventions. The text of the International Standard has been approved as suitable for publication as a British Standard without deviation. Some terminolo
10、gy and certain conventions are not identical with those used in British Standards; attention is drawn especially to the following. The comma has been used as a decimal marker. In British Standards it is current practice to use a full point on the baseline as the decimal marker. Wherever the words “I
11、nternational Standard” and “this part of ISO 789” appear, referring to this standard, they should be read as “British Standard” and “this Part of BS 6347” respectively. Cross-references. There are no corresponding British Standards for ISO612:1978 (which is referred to in clause2, 3.2, 3.4.1 and3.5.
12、3) or ISO3339-1 1)(which is referred to in clause3.1). As these standards are referred to for information only, the validity of this British Standard is not affected. NOTEIn the note to6.4 “weighbride” should be read as “weighbridge”. A British Standard does not purport to include all the necessary
13、provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to8, a
14、n inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. 1) At present at the stage of draft.BS6347-6:1983 BSI 03-2000 1 0 Introduction This Internation
15、al Standard specifies test procedures for agricultural tractors. This part deals with the centre of gravity. Other parts of this International Standard will be as follows: Part 1: Power tests; Part 2: Hydraulic power and lifting capacity; Part 3: Turning and clearance diameters; Part 4: Exhaust smok
16、e measurement; Part 5: Partial power p.t.o. non-mechanically transmitted power; Part 7: Power and torque of the drive wheels; Part 8: Engine air cleaner. Although there are many possible methods of determining the centre of gravity, the purpose of this part of ISO789 is to specify a simple, practica
17、l method, which requires the use of a weighbridge and crane. Alternative methods may be used if they locate the centre of gravity with respect to the specified reference planes and within the specified tolerances. 1 Scope and field of application This part of ISO 789 specifies a method of determinin
18、g the position of the centre of gravity of agricultural tractors. The method is applicable to agricultural tractors having at least two axles fitted with wheels or tracks. 2 Reference ISO 612, Road vehicles Dimensions of motor vehicles and towed vehicles Terms and definitions. 3 Definitions For the
19、purpose of this part of ISO789, the following definitions apply. 3.1 agricultural tractor see ISO 3339-1 (in preparation) 3.2 wheelbase see ISO 612 3.3 tractor mass the mass of a tractor as submitted for test 3.4 reference planes 3.4.1 vertical reference planes: a) transverse plane 1) for wheeled tr
20、actors: vertical plane containing the centreline of the rear axle; 2) 2) for crawler tractors: vertical plane containing the centreline of the driving sprocket axle; b) median longitudinal plan (or symmetric longitudinal plane): vertical plane through the major fore-and-aft axis, i.e.midway between
21、the tracks or wheels (see ISO612). 3.4.2 horizontal reference plane ground level. (A hard contact shall be assumed.) 3.5 coordinates of the centre of gravity 3.5.1 horizontal fore-and-aft coordinate (symbol ) the horizontal distance of the centre of gravity from the transverse reference plane 3.5.2
22、vertical coordinate (symbol ) the vertical distance of the centre of gravity from the horizontal reference plane 3.5.3 lateral coordinate (symbol ) the horizontal distance of the centre of gravity from the median longitudinal plane (see ISO612) of the tractor 4 Apparatus The following apparatus is r
23、equired. 4.1 Weighbridge or load cells 4.2 Crane 4.3 Decking with knife edges 4.4 Level 4.5 Plumb rule 4.6 Squares 4.7 Scribing board The scribing board shall be at least600mm high by450mm wide, rigidly constructed, and attached to the tractor in a suitable position with a smooth face vertical and p
24、arallel to the side or other appropriate plane. 2) For articulated tractors: locked in a straight line. x h yBS6347-6:1983 2 BSI 03-2000 4.8 Marking materials 4.9 Tape measure 5 General requirements The tractor shall be clean and shall be tested in normal working conditions or in a specified conditi
25、on agreed between the manufacturer and the testing authority. 5.1 The radiator, sump, hydraulic and other reservoirs shall be filled to specified working levels; the fuel tank shall be full or empty or in a specified condition as agreed between the manufacturer and the testing authority. 5.2 Tools,
26、spare tyre, and loose accessories and equipment shall be complete as supplied and shall be in the normal storage positions. 5.3 Tyre pressures shall be as specified in the manufacturers operating instructions or, if a range of pressures is allowed, at the highest recommended pressure. In the case of
27、 tractors fitted with hydro-inflation tyres, they shall be filled in accordance with the manufacturers operating instructions. 5.4 Articulated tractors shall normally be tested locked in a straight line, but it may be necessary to conduct the test with the joint set at the maximum or any intermediat
28、e angle. 5.5 If testing a sprung tractor, no special measures shall be taken to lock the suspension of the machine. 5.6 In conducting the test, the following measurement tolerances shall be observed: a) distance: 0,5% b) mass: 0,5% c) tyre pressure 3) : 5% 6 Procedure 6.1 General principle The centr
29、e of gravity is determined by the suspension and ground reaction method. This involves measuring the ground reactions with the tractor: a) in a horizontal position; b) tilted with one end lifted; c) tilted with the other end lifted. The calculated horizontal distance of the centre of gravity from a
30、ground contact point is measured in each case and verticals are drawn on the scribing board (4.5) fixed to the tractor. The intersection of the verticals indicates the centre of gravity. 6.2 Determination of horizontal fore-and-aft coordinate 6.2.1 Tracked tractors seeFigure 1a) Determine the mass (
31、m) of the whole tractor on the weighbridge. Measure the reaction (F 1 ) under the knife edge due to its mass and part of the decking. Move the tractor on to the decking, part supported by the weighbridge, and measure the reaction at the front knife edge due to the mass of the tractor, the decking an
32、d knife edge (F 1+ F 2 ). Calculate the reaction of the front knife edge due to the tractor mass only (F 2 ) by subtraction. Measure the distance (d) between the knife edges. The horizontal fore-and-aft coordinate is given by the formula 6.2.2 Wheeled tractors seeFigure 1b) In the case of wheeled tr
33、actors, it is not necessary to use decking or knife edges. With the brakes off, measure the axle loads and calculate from the mass and the wheelbase of the tractor by the formula given in6.2.1 (using the wheelbase as the value ford). 6.3 Determination of vertical coordinate (seeFigure 2) 6.3.1 Suspe
34、nd the tractor from one end at an angle of20 to25 to the horizontal, the other end resting on the weighbridge. For some tractors it may not be practical or safe to use an angle this large. In this case a lesser angle may be used, but shall not be less than15 to the horizontal. (The method is applica
35、ble either to wheeled or tracked tractors, the main difference being in establishing the exact location of the point of application of the ground contact. In the case of wheeled tractors, which shall be unbraked, this is vertically below the axle. In the case of tracked tractors, it is necessary to
36、manoeuvre until the contact grousers are in the line of ground contact BB on either side, or to make contact through a knife-edge on the ground contact line BB. In all cases, the suspension cable shall be vertical as tested by plumb rule.) 6.3.2 Measure the reaction (F 3 ) at the ground contact on t
37、he weighbridge. 6.3.3 Measure the horizontal distance (d) from the ground contact to the line of suspension. 3) Tyre pressure should be in accordance with the manufacturers recommendations. x () x dF 2 m - = x h ()BS6347-6:1983 BSI 03-2000 3 6.3.4 Calculate the horizontal distance (c) from the centr
38、e of gravity to the line of suspension from the formula where m is the mass of the tractor. 6.3.5 Draw a vertical on the scribing board at a distance c from the line of suspension. 6.3.6 Repeat the procedures specified in6.3.1 to6.3.5 with the tractor suspended from the other end. The suspension ang
39、le need not be the same for both ends. 6.3.7 The intersection of the two lines on the scribing board, determined as specified in6.3.5 and6.3.6, gives the vertical coordinate of the centre of gravity . NOTE 1The tractor may be conveniently run on to the weighbridge, square, using chalked lines. This
40、will assist in drawing the plan. If, in the case of tracked tractors, the grousers are not in the ground contact line BB (seeFigure 2), it is necessary to resort to trial and error by running the tractor in varying circles until the required result is attained at the last approach. NOTE 2An alternat
41、ive method is to use a tilting platform and load cells respectively. 6.4 Determination of lateral coordinate in the horizontal plane () (seeFigure 3) Measure the left-hand (F 4 ) and right-hand (F 5 ) wheel or track loadings. Calculate the offset (b) of the centre of gravity using track gauge or whe
42、el track (d t ) as the moment arm, i.e. The lateral coordinate in the horizontal plane is given by the formula NOTEIt will usually be found that the right-hand and left-hand side loads do not exactly total the mass of the tractor due to small differences in level between the weighbride deck and the
43、surround. Any error is minimized by equalizing the overlap of the side being weighed in both cases. It is preferable to use the total right-hand side and left-hand side wheel (track) loadings to determine the mass of the tractor (m). 7 Test report (see theAnnex) 7.1 The test report shall include the
44、 identification of the tractor and test parameters, together with the coordinates of the centre of gravity as follows: a) the horizontal fore-and-aft coordinate (): the distance from the vertical reference plane; b) vertical coordinate (): height above horizontal ground level; c) the lateral coordin
45、ate in the horizontal plane(): the displacement from the median longitudinal plane through the major fore-and-aft axis. 7.2 The position of the centre of gravity shall be reported in millimetres from three reference planes. c F 3 d m - = h y b F 5 d t m - = y d t 2 -b = x h yBS6347-6:1983 4 BSI 03-2
46、000 Figure 1 Determination of horizontal fore-and-aft coordinate x ()BS6347-6:1983 BSI 03-2000 5 Figure 2 Determination of vertical coordinate h ()BS6347-6:1983 6 BSI 03-2000 Figure 3 Determination of lateral coordinate in the horizontal plane y ()BS6347-6:1983 BSI 03-2000 7 Annex Specimen test repo
47、rt8 blankBS6347-6:1983 BSI 03-2000 Publications referred to See national foreword.BS 6347-6: 1983 ISO 789-6: 1982 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the UK view on standa
48、rds in Europe and at the international level. It is incorporated by Royal Charter. Revisions BritishStandards are updated by amendment or revision. Users of BritishStandards should make sure that they possess the latest amendments or editions. It is the constant aim of BSI to improve the quality of
49、our products and services. We would be grateful if anyone finding an inaccuracy or ambiguity while using this BritishStandard would inform the Secretary of the technical committee responsible, the identity of which can be found on the inside front cover. Tel:02089969000. Fax:02089967400. BSI offers members an individual updating service called PLUS which ensures that subscribers automatically receive the latest editions of standards. Buying standards Orders for al
