ISO 5692-3:2011

Overview

ISO 5692-3:2011 - "Agricultural vehicles - Mechanical connections on towed vehicles - Part 3: Swivel hitch rings" specifies requirements for swivel hitch rings used to attach agricultural trailers and implements to the rear of self-propelled agricultural vehicles fitted with a non-swivel clevis coupling (see normative reference ISO 6489-5). The standard defines geometry, mechanical performance descriptors and constructional and marking requirements to ensure safe, interchangeable mechanical connections between towing and towed agricultural equipment.

Key topics and technical requirements

• Scope and applicability: Applies where a non-swivel clevis coupling (ISO 6489-5) is used to connect trailers or implements to tractors and other self-propelled agricultural vehicles.
• Interchangeability dimensions: Hitch ring shapes (cylindrical or round eye configurations) and key dimensional parameters are specified (refer to Table 1 in the standard) to ensure compatibility and safe fit with corresponding couplings.
• Load parameters:
  • D value - representative horizontal (longitudinal) force on the coupling, expressed in kilonewtons (kN).
  • Vertical load S - static load at the coupling reference centre, expressed in kilograms (kg).
  • Allowable loads and corresponding ring shapes are listed in the standard to match performance requirements.
• Trailer shank travel angles: Minimum articulation requirements to prevent binding and allow safe operation:
  • Yaw: ±60° around vertical axis.
  • Pitch: ±20° top and bottom.
  • Roll: ±20° top and bottom.
  • An allowance of ±3° is given for towing machine inclination due to tyre size differences.
• Constructional requirements: Hitch rings shall be substantially toroidal or cylindrical and manufactured by forging. Removable rings are jointed to a sleeve fixed on the trailer drawbar.
• Permissible connections: Table 2 maps permissible mechanical connections between ring shapes (W, X, Y, Z) and corresponding ISO 6489-5 coupling shapes (w, x, y, z).
• Marking: Each swivel hitch ring must carry a permanent, visible ring-shape letter marking for identification.

Applications and who uses this standard

• Manufacturers of agricultural trailers, drawbars and towing couplings designing swivel hitch rings for interchangeability and safety.
• Tractor and implement OEMs specifying compatible couplings and hitch rings.
• Certification bodies and test labs assessing mechanical connections against ISO requirements.
• Procurement, maintenance and safety engineers ensuring correct replacement parts, correct installation and compliance.
• Agricultural fleet managers and workshop technicians verifying compatibility and safe towing arrangements.

Related standards

• ISO 6489-5:2011 (non-swivel clevis coupling) - normative reference
• ISO 5692-1:2004 (hitch ring dimensions)
• ISO 5692-2:2002 (coupling ring 40 with socket)
• Other ISO 6489 parts and ISO 20019/ISO 24347 for related coupling types

Keywords: ISO 5692-3:2011, swivel hitch rings, agricultural vehicles, hitch rings, clevis coupling, D value, interchangeability dimensions, forged hitch rings.