ISO 10061-1991 PDF

Full title and description

ISO 10061:1991 — Road vehicles — Trailers, including caravans — Height of coupling head. This short international standard specifies the nominal height and tolerance for the coupling head (centre of the spherical socket) for trailers that use coupling balls conforming to ISO 1103.

Abstract

ISO 10061:1991 defines the required vertical position of the trailer coupling head relative to the horizontal supporting surface: a nominal height of 430 mm with an allowable tolerance of ±35 mm. The requirement applies to small trailers of categories O1 and O2 that mate with coupling balls conforming to ISO 1103. The document is concise (2 pages) and intended to harmonize coupling geometry for towing compatibility.

General information

• Status: Withdrawn (national catalogs show withdrawal/retirement from the catalog).
• Publication date: October 1991 (published 16–17 October 1991).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 43.040.70 (Couplings — road vehicle coupling related standards).
• Edition / version: 1991 (first edition as published in 1991).
• Number of pages: 2 pages (concise technical specification).

Scope

Applies to trailers of categories O1 and O2 that use coupling balls complying with ISO 1103. Specifies the height of the centre of the coupling head measured from the horizontal support surface: (430 ± 35) mm. The standard's purpose is to ensure geometric compatibility between towing and towed vehicles for common small trailer classes.

Key topics and requirements

• Specified nominal coupling-head height: 430 mm, tolerance ±35 mm.
• Applicability limited to trailer categories O1 and O2 (small trailers/caravans that use ISO 1103 coupling balls).
• Measurement reference: centre of the spherical socket (coupling head) to horizontal supporting surface.
• Harmonization intent — ensures mechanical compatibility with standard coupling balls and related coupling geometry.

Typical use and users

Used by vehicle and trailer manufacturers, component suppliers (couplings and tow hitches), type-approval authorities, testing laboratories, and standards bodies when specifying or verifying trailer coupling geometry. It is primarily a dimensional/compatibility reference for design, inspection and regulatory compliance activities for small trailers and caravans.

Related standards

Standards referenced or closely related include ISO 1103 (specification for coupling balls/ball dimensions) and several national/industry documents that specify coupling location and measurement (for example DIN 74064 and related national adoptions). These documents collectively address mating geometry, coupling strength and installation practice.

Keywords

coupling head, coupling height, trailer, caravan, towing, ISO 1103, O1, O2, tow ball, coupling geometry, vehicle coupling.

FAQ

Q: What is this standard?

A: ISO 10061:1991 is an ISO technical standard that specifies the height of the coupling head for road trailers (including caravans) that use ISO 1103 coupling balls.

Q: What does it cover?

A: It covers a single dimensional requirement — the vertical position (height) of the centre of the coupling head above the horizontal supporting surface, given as 430 mm with a ±35 mm tolerance, and applies to trailer categories O1 and O2.

Q: Who typically uses it?

A: Trailer and caravan manufacturers, towbar and coupling suppliers, vehicle type-approval and inspection authorities, and test labs use it to ensure geometric compatibility between tow vehicles and trailers.

Q: Is it current or superseded?

A: The standard is listed as withdrawn in national catalogs (withdrawal was recorded in national registries cataloging ISO standards); users should verify current national/regulatory requirements or later ISO documents before relying on it for compliance.

Q: Is it part of a series?

A: It is a standalone dimensional specification but is functionally related to other vehicle-coupling standards (for example ISO 1103 for coupling balls) and to national standards addressing coupling location such as DIN 74064.

Q: What are the key keywords?

A: Coupling height; coupling head; tow ball; trailer O1; trailer O2; ISO 1103; coupling geometry; towing compatibility.