Specifies the requirements for towbars and towing brackets for use with 50mm towballs, intended for trailers and caravans up to 3.5t aggregate trailer mass, for use on public roads.

This Standard specifies requirements for towbars and towing brackets suitable for use with 50 mm towballs complying with AS 4177.2. The towbars are intended for trailers and caravans of up to 3.5 t aggregate trailer mass, for use on public roads.A method for determining the static strength of a towbar and its attachment to the vehicle structure is given in Appendix A and for safety chain connections is given in Appendix B. A method of determining the dynamic strength of a towbar and its attachment to the vehicle structure is given in Appendix C. NOTES: 1 Towballs are specified in AS 4177.2, and their corresponding coupling bodies in AS 4177.3. 2 Requirements for off-road applications are beyond the scope of this Standard. 3 Requirements for load-distributing hitches are not included in this Standard. 4 Towbars should not be used for other than their intended purpose of towing caravans and light trailers.

First published as part of AS D18-1968.Revised and redesignated in part as AS 4177.1-1994.Second edition 2004. 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).