ISO 2331:1974

Overview - ISO 2331:1974 (Fork lift trucks - Hook-on type fork arms - Vocabulary)

ISO 2331:1974 is a trilingual vocabulary standard that defines the terminology used for hook-on type fork arms for fork lift trucks. Published as the first edition in 1974, the document provides consistent English, French and Russian terms and illustrations for parts, surfaces and dimensional concepts of fork arms. It is intended to be used in conjunction with related standards ISO 2328, ISO 2329 and ISO 2330 (mounting dimensions, fork arm dimensions and technical characteristics/testing).

Key topics and definitions

ISO 2331 focuses on precise naming and description rather than prescriptive measurements. Key technical topics covered include:

• Fork parts and their names:
  • blade (horizontal portion supporting the load)
  • heel (angled portion connecting blade to shank)
  • shank (vertical portion carrying hooks)
  • hooks (top and bottom hooks - suspension and restraint)
  • tip (free end of the blade)
  • positioning lock (device for locating the fork on the carrier)
• Fork surfaces and functional faces:
  • blade upper face and lower face
  • shank front face (load-contact face used to measure load centre)
  • flanks (side faces), hook-retaining faces, hook suspension face
  • blade taper and toe (profiles to facilitate insertion)
• Dimensional terms used to describe forks:
  • thickness (a), width (b), height (h), length (l)
  • cross-section (A = a × b)
  • angle (α) between blade upper face and shank front face
• Illustrative figures that show the meaning and relative location of parts and surfaces.

Practical applications

ISO 2331 provides a standard vocabulary to ensure clarity across documentation, design, testing and procurement processes. Typical uses include:

• Preparing technical drawings, specifications and datasheets for fork arms and attachments
• Writing test reports and inspection records consistent with ISO 2330 testing terminology
• Vendor and purchaser contracts and product manuals where consistent terminology reduces ambiguity
• Translation and multilingual documentation (English/French/Russian) for international supply chains
• Training materials and safety procedures that reference correct part names and measurement points

Who should use this standard

• Fork lift and attachment manufacturers
• Design and mechanical engineers
• Test laboratories and certification bodies
• Maintenance, inspection and safety teams
• Technical writers, translators and procurement specialists

Related standards

• ISO 2328 - mounting dimensions for hook-on type fork arms and fork carriers
• ISO 2329 - fork arms - dimensions
• ISO 2330 - fork arms - technical characteristics and testing

Using ISO 2331 alongside these standards helps ensure consistent terminology when specifying, testing and maintaining hook-on fork arms for forklift trucks.