This Standard is Part 1 of AS 4177, Caravan and light trailer towing components, which is published in Parts as follows:

Part 1: Towbars and towing brackets (this Standard)
Part 2: 50 mm towballs
Part 3: Coupling body for ball couplings
Part 4: Safety chains up to 3500 kg capacity
Part 5: Electrical connectors

The objective of this Standard is to provide manufacturers and users with design and installation dimensions for a 50 mm towball on a towbar, intended for trailers and caravans of up to 3.5 t aggregate trailer mass, for use on public roads.

A static test based on 1.5 times the rated capacity of the towbar has been prepared for Australian conditions, and a dynamic test in accordance with ISO 3853:1994, Road vehicles—Towing vehicle coupling device to tow caravans or light trailers—Mechanical strength test, has been added as an alternative for compliance with European requirements.

In this revision, Amendments No. 1 and No. 2 to the 1994 edition have been incorporated, and the towball upper limit height above the ground has been increased from 420 mm to 460 mm.

The term ‘normative’ has been used in this Standard to define the application of the appendix to which it applies. A ‘normative’ appendix is an integral part of a Standard.

Specifies the requirements for towbars and towing brackets for use with 50 mm towballs, intended for trailers and caravans up to 3.5 t aggregate trailer mass, for use on public roads. Originated as part of AS D18-1968. Previous edition AS 4177.1-1994. Second edition 2004. Reissued incorporating Amendment No. 1 (April 2006). Reissued incorporating Amendment No. 2 (November 2006).