This part of ISO6489 gives specifications for the clevis couplings used in the attachment to agricultural towing vehicles of towed, non-balanced trailers and implements equipped with a coupling ring 40as specified in ISO5692-2 and ISO8755.
The mounting of one of the three trailer coupling shapes, A, B or C, on an agricultural vehicle or trailer is at the manufacturer\'s or user\'s discretion. The full interchangeability of the three shapes is provided for.