BS ISO 6489-3:2021 pdf download – Agricultural vehicles — Mechanical connections between towed and towing vehicles Part 3: Tractor drawbar
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
— IEC Electropedia: available at
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.
3.1.1 non-adjustable drawbar fixed drawbar with no possibility for adjustment
3.1.2 adjustable drawbar adjustable, multiple operating position drawbar providing the regular, short and extended drawbar positions
4.4 Drawbar location and position
The drawbar location and position shall conform to Figure 1 and Tables 2 and 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. To provide adequate articulation between the tractor and implement, it is recommended that the implement end be designed to allow ±20° of fore‑aft pitch and ±20° of side‑to‑side roll between the tractor and the implement. See Figure 4 for identification of the pitch, roll and yaw/articulation angles. For category 4 and 5 drawbars the roll and pitch should be ±15°. The maximum roll and pitch angles do not need to be met simultaneously.BS ISO 6489-3 pdf download.