本国际标准规定了非平衡农业机械附件的尺寸要求 拖车和机具通过挂接环安装在配备ISO规定挂钩的牵引车后部 6489-1. 其目的是确保农业牵引车上机械连接的互换性 车辆。 本国际标准适用于耦合点低于后轴中心线的环，以及 拖拉机的动力输出轴（PTO）。 注:将为PTO联轴器上方的环制定其他国际标准。

This International Standard specifies dimensional requirements for the attachment of agricultural, non-balanced trailers and implements by means of hitch rings to the rear of towing vehicles equipped with a hook specified in ISO 6489-1. Its purpose is to ensure the interchangeability of the mechanical connections on agricultural towed vehicles. This International Standard is applicable to rings whose coupling point is below the centre-line of the rear axle and the power take-off (PTO) of the tractor. NOTE Other International Standards are to be developed for rings above the PTO coupling.