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IS0
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I NT ERN AT1 ON A L O RG A N IZ AT I O N FOR STA N DA RD lZATl ON
IS0 RECOMMENDATION
R 730
THREE-POINT LINKAGE OF AGRICULTURAL WHEELED TRACTORS
FOR ATTACHMENT OF MOUNTED IMPLEMENTS
1 st EDIT ION
May 1968
COPYRIGHT RESERVED
The copyright of IS0 Recommendations and IS0 Standards
belongs to IS0 Member Bodies. Reproduction of these
documents, in any country, may be authorized therefore only
by the national standards organization of that country, being
a member of ISO.
For each individual country the only valid standard is the national standard of that country.
Printed in Switzerland
Also issued in French and Russian. Copies to be obtained through the national standards organizations.
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BRIEF HISTORY
The IS0 Recommendation R 730, Three-point linkage of agricultural wheeled tractors for
attachment of mounted implements, was drawn up by Technical Committee ISO/TC 22, Auto-
mobiles (Section ISOITC 22(T) - Agricultural Tractors), the Secretariat of which is held by the
Association Française de Normalisation (AFNOR).
Work on this question by the Technical Committee began in 1954 and led, in 1962, to tlie
adoption of a Draft IS0 Recommendation.
In December 1965, this Draft IS0 Recommendation (No. 876) was circulated to all the IS0
Member Bodies for enquiry. It was approved, subject to a few modifications of an editorial nature,
by the following Member Bodies :
Australia France Sweden
Austria Hungary Switzerland
Belgium Israel Turkey
Brazil Italy U.A.R.
Bulgaria Japan United Kingdom
Canada Netherlands U.S.A.
Chile New Zealand Yugoslavia
Czechoslovakia Poland
Finland Spain
Three Member Bodies opposed the approval of the Draft :
Germany
Portugal
U.S.S.R.
The Draft IS0 Recommendation was then submitted by correspondence to the IS0 Council
which decided, in May 1968, to accept it as an IS0 RECOMMENDATION.
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ISOlR 730-1968 (E
IS0 Recommendation R 730 May 1968
THREE-POINT LINKAGE OF AGRICULTURAL WHEELED TRACTORS
FOR ATTACHMENT OF MOUNTED IMPLEMENTS
1. SCOPE
This IS0 Recommendation covers requirements for the attachment of implements or equipment to
the rear of agricultural wheeled tractors by means of a three-link hitch in association with a power
lift.
2. FIELD OF APPLICATION
Two categories of dimensions are specified, the recommended use of each being distinguished
according to the drawbar pull during the first five hour test specified by the test code for tractors
(drawbar tests at 75 of the pull corresponding to maximum drawbar power, in the gear selected).
Category I : only intended for light-medium wheeled tractors, i.e. tractors showing a test
result of up to 1150 kgf (2500 lbf), that is 1125 daN, drawbar pull.
Cutegow 2 : intended for medium-heavy wheeled tractors, i.e. tractors showing a test result
of more than 11 50 kgf (2500 lbf), that is 11 25 daN,drawbar pull.
3. DEFINITIONS OF TERMS
3.1 General
3.1.1 Linkage. Combination of one upper link and two lower links, each articulated to the tractor
and the implement at opposite ends, in order to connect the implement to the tractor.
3.1.2 Hitch point. Articulated connection between a link and the implement; for geometrical
purposes the hitch point is the centre of the articulated connection between a link and the
implement.
3.1.3 Link point. Articulated connection between a link and the tractor; for geometrical purposes
the link point is the centre of the articulated connection between a link and the tractor.
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ISO/R 730-1968 (E)
Y
FIG. 1 - Components and dimensional characteristics of three-point linkage
(See clauses 3.2 and 3.3)
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ISOlR 730-1968 (E)
3.2 Components of the linkage
The numbers given hereunder refer to Figure 1.
upper link1 Elements of the linkage, each fitted with an articulated connection at both
2. Lower link J ends*
3. Upper hitch point. Articulated connection between the upper link and the implement.
4. Lower hitch point. Articulated connection between a lower link and the implement.
5. Upper link point. Articulated connection between the upper link and the tractor.
6. Lower link point. Articulated connection between a lower link and the tractor
7. Upper hitch pin. Pin, usually detachable and forming part of the upper link assembly, by
which the upper link is connected to the implement.
8. Lower hitch pin. Pin, usually attached rigidly to the implement, on which a lower link is
secured.
9. Upper link pin. Pin by which the upper link is connected to the tractor.
10. Cotter pin. Pin, usually fitted with a spring retaining device, by which an articulated connec-
tion is retained in position.
11. Lift rods. Connections that transmit force to the lower links for raising and lowering.
12. Mast. Component that provides location of the upper hitch point on the implement.
3.3 Dimensional characteristics of the linkage
The numbers given hereunder refer to Figure 1.
13. Mast height. Vertical distance between the upper hitch point and the common axis of the
lower hitch points.
14. Lower hitch points height. Height of the centre of the lower hitch points above ground level
when they are in the fully lowered position.
15. Levelling adjustment range. Movement, measured vertically, of one lower hitch point higher
or lower than the other, to provide an inclination of the implement.
16. Lower hitch point span. Distance between the shoulders of the lower hitch pins against
which the sides of the lower link ball joints abut.
17. Cotter-hole distance. Distance from the centre line of the cotter-hole to the shoulder of the
hitch pin.
18. Power range. Total vertical movement of the lower hitch points corresponding to the power
travel of the lift, excluding any adjustment in the linkage or lift rods.
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ISO/R 730 -1968 (E
19. Transport height. Height of the lower hitch points above the ground utilizing the full extent
of manual adjustment provided in the lift rods in conjunction with the power range, the
lower hitch point axis being maintained horizontal to the ground in a transverse plane.
20. Lower hitch point clearance. Clearance expressed as a radial dimension from a lower hitch
point to the outside diameter of the tyre, mudguard or other part of the tractor, measured
in a longitudinal vertical plane with the i
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