ISO 6489-3:2021 pdf download – Agricultural vehicles — Mechanical connections between towed and towing vehicles — Part 3: Tractor drawbar.
1 Scope This document specifies the dimensional requirements and location for category 0, 1, 2, 3, 4 and 5 drawbars mounted on the rear of agricultural tractors. 2 Normative references The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 789-1, Agricultural tractors — Test procedures — Part 1: Power tests for power take-off ISO 5673-2, Agricultural tractors and machinery — Power take-off drive shafts and power-input connection — Part 2: Specification for use of PTO drive shafts, and position and clearance of PTO drive line and PIC for various attachments ISO 14396, Reciprocating internal combustion engines — Determination and method for the measurement of engine power — Additional requirements for exhaust emission tests in accordance with ISO 8178 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses: — ISO Online browsing platform: available at https://www.iso .org/obp — IEC Electropedia: available at http://www.electropedia .org/ 3.1 tractor drawbar drawbar mechanical connection mounted on the rear of an agricultural tractor for the mechanical coupling of an implement Note 1 to entry: A tractor drawbar can be non-adjustable or adjustable.
3.1.3 regular drawbar position position of the adjustable drawbar (3.1.2) and non-adjustable drawbar (3.1.1) providing the standard dimension from drawbar pin hole to end of PTO for the type of PTO on the tractor 3.1.4 short drawbar position position of the adjustable drawbar intended to connect non-PTO driven equipment that applies a high vertical load to the drawbar 3.1.5 extended drawbar position position of the adjustable drawbar intended for a special PTO drive shaft condition where equal angularity of the drive shaft joints cannot be obtained using the regular drawbar position (3.1.3) 3.2 PTO drive shaft clearance plane imaginary plane which establishes the upper permissible limit of protrusion of the drawbar and clevis 3.3 drawbar hitch point connection point between tractor drawbar (3.1) and implement end
4 Specifications 4.1 Drawbar clevis The drawbar clevis shall be removable to allow installation of special attachments or connection to implements which have a clevis end (see Figure 6 ). It may also be necessary to remove the clevis to provide PTO driveshaft clearance with implements which do not meet the dimensions specified in ISO 5673-2. 4.2 Drawbar hitch point Provisions shall be made on the tractor for the connection of the tractor drawbar to the implement, in a position with the drawbar hitch point directly in line with the longitudinal centreline of the tractor PTO.
Longitudinal distance, L , should be 25 mm minimum for all drawbar categories. For wheeled tractors, this distance is from the centre of the hitch pin hole to the tire OD as shown in Figure 2 . For tracked tractors, this distance is from the centre of the hitch pin hole to the rear most vertical tangent line with the tracks at their rearmost pivoted position, as shown in Figure 3 .
5 Vertical drawbar load The maximum static vertical downward loads which the implement imposes on the tractor drawbar shall be in accordance with Table 6 for the regular, short and extended drawbar positions. If the configuration of the implement induces high dynamic vertical loads on the drawbar, the static load should be reduced to keep the dynamic load under control. Proper ballasting of the tractor is required to maintain stability when the loads specified in Table 6 are applied to the tractor drawbar. It is not a recommended practice for towed vehicles to impose upward loads to the tractor drawbar.
6 PTO drive shaft clearance The clearance dimensions given for the PTO in this document and for the PIC in ISO 5673-2 provide clearance between the PTO drive shaft and the drawbar clevis. See Figure 6 and Table 7. Clearance is provided when the fore-aft pitch between the implement and tractor is less than 20° for drawbar categories 0, 1, 2, and 3; and is less than 15° for drawbar categories 4 and 5.
