ISO 6786:1980

Overview

ISO 6786:1980 defines an identification system for pipe connections on units of air braking systems used in motor vehicles and trailers. The standard requires numeric codes to be placed close to port openings on units and permits the same coding to be used on schematic diagrams of braking systems. It establishes one- and two‑digit designations to make port functions unambiguous for manufacture, assembly and maintenance.

Key Topics and Requirements

• Scope: Applies to motor vehicles and their trailers; also suitable for schematic diagrams of braking systems.
• Identification format:
  • Primary code is a one-digit number (0–9) identifying the principal function of the port.
  • A second digit may be added when several similar connections exist; second digits should start at 1 and continue sequentially (e.g., 21, 22, 23).
  • If a single connection can perform multiple functions in one application, it is identified by two first digits separated by a dash (e.g., 1-2).
  • Where one connection can serve different functions in different applications (e.g., multiway valves), identification should be agreed between manufacturer and customer.
• Sample first-digit meanings (as specified in the standard):
  • 0 - Suction connection
  • 1 - Energy inlet
  • 2 - Energy supply (not to atmosphere)
  • 3 - Exhaust / connection to atmosphere (venting)
  • 4 - Pilot connection (entry into unit)
  • 5, 6 - Spare designations
  • 7 - Anti-freeze liquid connection (inlet/outlet sub-codes exist)
  • 8 - Lubricating oil connection (e.g., for compressor)
  • 9 - Cooling liquid connection (for compressor)
• Reserved two-digit codes: The standard defines specific two-digit usages (examples include 21 - energy supply to reservoir, 22 - switching connection; 71/72 for anti-freeze inlet/outlet; 81/82 for lubricating oil inlet/outlet; 91/92 for cooling liquid inlet/outlet).
• Placement: Digits must be placed close to the ports on the physical units for clear identification.

Applications and Users

ISO 6786 is practical for:

• Vehicle manufacturers and trailer builders (standardized port marking for production and quality control)
• Component suppliers and pneumatic valve manufacturers (consistent port coding across parts)
• Brake-system designers and integrators (clear interface definitions on units and schematics)
• Maintenance technicians and fleet service teams (rapid identification of ports for diagnostics and repair)
• Technical documentation authors and schematic diagram designers (unified labeling for troubleshooting and training)

Benefits include improved interoperability, reduced assembly errors, faster servicing, and clearer documentation for air braking systems.

Related Standards

• Developed by ISO Technical Committee ISO/TC 22 (Road vehicles).
• Best used alongside other ISO standards and vehicle braking system specifications to ensure complete compliance and compatibility.

Keywords: ISO 6786, air braking systems, identification of connections, pipe connections, braking-system ports, vehicle trailers, port coding, pneumatic braking.