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1、INTERNATIONAL STANDARD IS0 789-6 First edition AMENDMENT 1 1982-09-01 1996-06-1 5 Agricultural tractors - Test procedures - Part 6: Centre of gravity AMENDMENT 1 Tracteurs agricoles - MBthodes dessai - Partie 6: Centre de gravite AMENDEMENT 1 This material is reproduced from IS0 documents under Inte
2、rnational Organization for Standardization (ISO) Copyright License number IHSllCC11996. Not for resale. No patt of these IS0 documents may be reproduced in any form. electronic retrieval system or otherwise, except as allowed in the copyright law of the country of use, or with the prior written cons
3、ent of IS0 (Case postale 56,1211 Geneva 20, Switzerland, Fax +4122 734 10 79), IHS or the IS0 Licensors members. Reference number IS0 789-6:1982/Amd.l:1996(E) COPYRIGHT International Organization for Standardization Licensed by Information Handling Services COPYRIGHT International Organization for S
4、tandardization Licensed by Information Handling Services IS0 7l) 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, .e. midway between the
5、 tracks or wheels (see IS0 612). The method is applicable to agricultural tractors having at least 3-42 horizontal reference plane : Ground level. (A hard two axles fitted with wheels or tracks. contact shall be assumed.) 3.5 coordinates of the centre of gravity : 2 Reference 3.5.1 horizontal fore-a
6、nd-aft coordinate (symbol 3 : The IS0 612, Road vehicles - Dimensions of motor vehicles and horizontal distance of the centre of gravity from the transverse towed vehicles - Terms and definitions. reference plane. 1) For articulated tractors : locked in a straight line. 1 COPYRIGHT International Org
7、anization for Standardization Licensed by Information Handling Services COPYRIGHT International Organization for Standardization Licensed by Information Handling Services IS0 789/6-1982 (E) 3.5.2 vertical coordinate (symbol T) : The vertical distance of the centre of gravity from the horizontal refe
8、rence plane. 3.5.3 lateral coordinate (symbol fl : The horizontal distance of the centre of gravity from the median longitudinal plane (see IS0 612) of the tractor. 4 Apparatus The following apparatus is required. 4.1 Weighbridge or load cells. 4.2 Crane. 4.3 Decklng with knife edges. 4.4 Level. 4.5
9、 Plumb rule. 4.6 Squares. 4.7 Scribing board. The scribing board shall be at least 600 mm high by 450 mm wide, rigidly constructed, and attached to the tractor in a suitable position with a smooth face vertical and parallel to the side or other appropriate plane. 4.8 Marking materials. 4.9 Tape meas
10、ure. 5 General requirements The tractor shall be clean and shall be tested in normal working conditions or in a specified condition 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
11、tank shall be full or empty or in a specified condition as agreed between the manufacturer and the testing authority. 5.2 Tools, 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
12、 manufacturers operating instructions or, if a range of pressures is allowed, at the highest recommended pressure. In the case of tractors fit- ted with hydro-inflation tyres, they shall be filled in accordance with the manufacturers operating instructions, 5.4 Articulated tractors shall normally be
13、 tested locked in a straight line, but it may be necessary to conduct the test with the joint set at the maximum or any intermediate 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
14、 tol- erances shall be observed : a) distance : b) tilted with one end lifted; c) tilted with the other end lifted. The calculated horizontal distance of the centre of gravity from a ground contact point is measured in each case and verticals are drawn on the scribing board (4.5) fixed to the tracto
15、r. The intersection of the verticals indicates the centre of gravity. 6.2 Determination of horizontal fore-and-aft coordinate (55) 6.2.1 Tracked tractors see figure 1 all Determine the mass (m) of the whole tractor on the weigh- bridge. Measure the reaction (Fl) under the knife edge due to its mass
16、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 and knife edge (F1 + F*). Calculate the reaction of the front knife edge due to the tractor mass only (F2) by s
17、ubtraction. Measure the distance (dl between the knife edges. The horizontal fore-and-aft coordinate is given by the formula - d * F2 x =- - m 1) Tyre pressure should be in accordance with the manufacturers recommendations. 2 COPYRIGHT International Organization for Standardization Licensed by Infor
18、mation Handling Services COPYRIGHT International Organization for Standardization Licensed by Information Handling Services 6.2.2 Wheeled tractors see figure 1 b)l In the case of wheeled tractors, it is not necessary to use deck- ing or knife edges. With the brakes off, measure the axle loads and ca
19、lculate Trom the mass and the wheelbaseof the tractor by the formula given in 6.2.1 (using the wheelbase as the value for dl. 6.3 Determination of vertical coordinate (E) (see figure 2) 6.3.1 Suspend the tractor from one end at an angle of 20 to 25O to the horizontal, the other end resting on the we
20、ighbridge. (The method is applicableeither 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 track
21、ed tractors, it is necessary to 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 suspen- sion cable shall be vertical as tested by plumb rule.) 6.3.2 Measure the reactio
22、n (F3) at the ground contact on the weighbridge. 6.3.3 Measure the horizontal distance (d) from the ground contact to the line of suspension. 6.3.4 . Calculate the horizontal distance (c) from the centre of gravity to the line of suspension from the formula F 3 * d c =- m where m is the mass of the
23、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 in 6.31 to 6.3.5 with the tractor suspended from the other end. The suspension angle need not be the same for both ends. 6.3.7 The intersection of the two lines on
24、the scribing board, determined as specified in 6.3.5 and 6.3.6, gives the vertical coordinate of the centre of gravity (h). NOTES 1 The tractor may be conveniently run on to the weighbridge, square, using chalked lines. This will assist in drawing the plan. If, in the case of tracked tractors, the g
25、rousers are not in the ground contact line BB (see figure 21, 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. 2 An alternative method is to use a tilting platform and load cells respectively. 6.4 Deter
26、mination of lateral coordinate in the horizontal plane (fl (see figure 3) Measure the left-hand (F4) and right-hand (F5) wheel or track loadings. Calculate the offset, (b) of the centre of gravity using track gauge or wheel track (d,) as the moment arm, .e. F54 m b =- The lateral coordinate in the h
27、orizontat plane is given by thefor- mula - dt y =“ 6 2 NOTE - It 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 dif- ferences in level between the weighbride deck and the surround. Any error is minimized by equalizing the
28、overlap of the side being weighed in both cases. ltis preferable to use the tofal right-hand side and left-hand side wheel (track) loadings to determine the mass of the tractor (m). 7 Test report (see the annex) 7.1 The test report shall include the identification of the trac- tor and test parameter
29、s, together with the coordinates of the centre of gravity as follows : a) the horizontal fore-and-aft coordinate (33 : the distance from the vertical reference plane; b) vertical coordinate (x) : height above horizontal ground level; c) the lateral coordinate in the horizontal plane (3. : the displa
30、cement 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. 3 COPYRIGHT International Organization for Standardization Licensed by Information Handling Services COPYRIGHT Intern
31、ational Organization for Standardization Licensed by Information Handling Services IS0 789/6-1982 (E) m - U ,-Centre of gravity m I l Weighbridge Vertical reference plane d 4 I 2 I Weighbridge I I i d jF2 Vertical reference plane a) Tracked tractor b) Wheeled tractor Figure 1 - Determination of hori
32、zontal fore-and-aft coordinate (3 /- cable Suspension I Weighbridge F3 r cable Suspension Y? I I Ai Weighbridge Figure 2 - Determination of vertical coordinate (T) 4 COPYRIGHT International Organization for Standardization Licensed by Information Handling Services COPYRIGHT International Organizatio
33、n for Standardization Licensed by Information Handling Services m I II F4 I Track Figure 3 - Determination of lateral coordinate in the horizontal plane (y) 5 COPYRIGHT International Organization for Standardization Licensed by Information Handling Services COPYRIGHT International Organization for S
34、tandardization Licensed by Information Handling Services IS0 789/6-1982 (E) Manufacturers name and address Tractor type : . Serial No. : . Annex Specimen test report Model: . Description of the main tractor specifications influencing the position of the centre of gravity (for example, if provided wi
35、th a cabin, state the type) : . . . . Tyre inflation pressures : front kPa rear . kPa Tyresize: front . rear Tractor mass (m) : front . kg rear . kg for wheeled tractors total . kg Coordinates of the centre of gravity : - . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mm R mm y . mm 6 COPYRIGHT International Organization for Standardization Licensed by Information Handling Services COPYRIGHT International Organization for Standardization Licensed by Information Handling Services