ISO 730:2009 pdf free download – Agricultural wheeled tractors – Rear-mounted three-point linkage一 Categories 1N, 1, 2N, 2, 3N, 3, 4N and 4.
3.1.4
three-point hitch coupler
device which facilitates the connection of the tractor three-point linkage to the implement
NOTE For examples, see References [5] to [8].
3.1.5
narrow-hitch
N
standard hitch in all dimensions except for the lower hitch point span, which is that of the next smallest category
EXAMPLE A category 3N hitch can also be a category 2 hitch in all dimensions excepting the upper and lower hitch point pin diameters, which are category 3.
3.2 Three-point linkage components and dimensions (see Figure 1)
3.2.1
upper link
upper linkage element, fitted with an articulated connection at both ends
3.2.2
lower link
lower linkage element, fitted with an articulated connection at both ends
3.2.3
upper hitch point
articulated connection between the upper link and the implement.
3.2.4
lower hitch point
articulated connection between a lower link and the implement
NOTE 1 Mast adjustment is not shown in Figure 1.
NOTE 2 Adjustment of the mast controls the pitch of the implement. Specifying the mast adjustment to be provided enables the tractor designer to determine the minimum acceptable adjustment of the length of the top link in relation to the points of attachment of the linkage. It also permits the implement designer to determine the range of operating depths of the implement over which pitch adjustment can be obtained.
3.2.23
torsional free float distance
vertical distance over which either of the lower hitch points can move freely relative to the other to allow the implement to roll, with lower links initially horizontal
3.2.24
transport pitch
pitch reached by the mast when lifted to standard transport height from a position with lower links horizontal and mast vertical
3.2.25
horizontal convergence distance
horizontal distance from the lower hitch points to the point of convergence of the lower links when the lower links are horizontal and laterally symmetrical, seen in a plan view
NOTE See Annex A.
3.2.26
vertical convergence distance
horizontal distance from the lower hitch points to the point of convergence formed in the vertical longitudinal plane by the top link and the lower links
NOTE See Annex A.
4 Tractor requirements
4.1 Categories
The categories of rear-mounted three-point linkages to be used on the various ranges of agricultural tractors are given in Table 1.
Category 1 N and 2N apply to narrow-track agricultural wheeled tractors.
Certain specialized implements or farming operations that require narrow spacing require special consideration for the three-point linkage. Categories 3N and 4N hitch categories have been established to respond to these requirements.
Dimensions and requirements for the three-point linkage for the attachment of implements or equipment to the front of agricultural tractors are given in ISO 8759-1.
4.2 Dimensions
4.2.1 General
Dimensions apply to the tractor equipped with the normal range of tyre sizes as recommended by the tractor
manufacturer.
4.2.2 Hitch points
The dimensions related to the hitch points shall be in accordance with Figures 2 and 3, and Table 2.
4.2.3 Upper link point
Upper link point arrangements shall be provided so that the transport pitches of — 3° to + 30 and ± 100 to ± 15° can be achieved at the standard mast height.
4.2.4 Torsional free float
Torsional free float shall be provided at a distance specified in Table 3. It shall be possible to block the torsional free float.