NZS 5446:2024
On-road heavy vehicle towing connections – Drawbeams and drawbars
NZS 5446 On-road Heavy Vehicle Towing Connections – Drawbeams and Drawbars establishes the design, manufacture, installation, testing, maintenance, repair, and certification criteria that are necessary to ensure that a secure connection can be maintained between towing vehicles and drawbar trailers for normal use by heavy road vehicles on sealed and unsealed roads.
Although this standard primarily covers applications incorporating pin or hook couplings, it also applies to other types of couplings covering rigid and hinged drawbars.
This standard includes the following components:
(a) Drawbeam;
(b) Drawbar;
(c) Couplings;
(d) Attachment method:
(i) Towing vehicle chassis
(ii) Main structural member of the trailer chassis or steering axle assembly.
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NZS 5446:2024 On-road heavy vehicle towing connections – Drawbeams and drawbars
Committee representation
Acknowledgement
Copyright
CONTENTS
Referenced documents
Latest revisions
Review of standards
Foreword
1 GENERAL
1.1 Scope
1.2 Interpretation
1.3 Definitions
1.4 Abbreviations
2 DESIGN
2.1 Design requirements – loading
2.2 Design stresses
2.3 Components and assemblies with D values
2.4 Design considerations
2.5 Materials of construction
2.6 Brittle fracture
2.7 Bolted connections
3 DRAWBEAMS
3.1 Design forces
3.2 Attachment
3.3 Location
3.4 Certification
3.5 Identification
3.6 Welding
3.7 Repair
4 DRAWBARS
4.1 Design forces
4.2 Attachment
4.3 Articulation
4.4 Certification
4.5 Identification
4.6 Telescopic drawbars
4.7 Pole trailers
4.8 Additional design considerations
4.9 Welding
4.10 Repair
5 COUPLINGS
5.1 Coupling standards
5.2 Capacity
5.3 Vertical load capacity
5.4 Articulation
5.5 Coupling location
5.6 Safety lock
5.7 Maintenance and inspection
Appendix
Appendix A – Design stresses and design life
Appendix B – Drawbeam and drawbar structural components that are tested and approved to an international standard
Appendix C – Drawbars with vertical loadings
Appendix D – Re-certification
Appendix E – Side force on drawbars without turntable locks
Appendix F – Explanatory notes on the 2007 and 2024 revisions of the standard
Figure 1 – Dimensions of the simple trailer
Figure 2 – Example of a drawbeam identification label
Figure 3 – Examples of couplings and drawbeam assembly
Figure 4 – Example of a drawbar identification label
Figure 5 – Example of a drawbar and attachment
Figure C1 – Coupling forces for a drawbeam with a vertical load
Figure E1 – Tandem-axle set and tri-axle set
Table 1 – Design loads for specified maximum towed mass (MTM)
Table B1 – Minimum D value for a specified maximum towed mass (MTM)
Previous versions
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References
Structural steel welding - Part 1: Welding of steel structures
Structural steel welding - Part 4: Welding of high strength quenched and tempered steels
Structural steel welding - Part 5: Welding of steel structures subject to high levels of fatigue loading
Aluminium structures - Allowable stress design
Welding of aluminium structures
Related Information
Similar Standards
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AS/NZS 4968.1:2023
Heavy road vehicles – Mechanical coupling between articulated vehicle combinations, Part 1: Design criteria and selection requirements for fifth wheel, kingpin and associated equipment
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AS/NZS 4968.2:2023
Heavy road vehicles – Mechanical coupling between articulated vehicle combinations, Part 2: Testing and installation of fifth wheel and associated equipment
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AS/NZS 4968.3:2023
Heavy road vehicles – Mechanical coupling between articulated vehicle combinations, Part 3: Kingpins and associated equipment
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BS 7961:2004
Specification for a device for measuring the static vertical mass (noseweight)at the coupling point of the towed vehicle.
NZS 5446:2024 On-road heavy vehicle towing connections – Drawbeams and drawbars
Committee representation
Acknowledgement
Copyright
CONTENTS
Referenced documents
Latest revisions
Review of standards
Foreword
1 GENERAL
1.1 Scope
1.2 Interpretation
1.3 Definitions
1.4 Abbreviations
2 DESIGN
2.1 Design requirements – loading
2.2 Design stresses
2.3 Components and assemblies with D values
2.4 Design considerations
2.5 Materials of construction
2.6 Brittle fracture
2.7 Bolted connections
3 DRAWBEAMS
3.1 Design forces
3.2 Attachment
3.3 Location
3.4 Certification
3.5 Identification
3.6 Welding
3.7 Repair
4 DRAWBARS
4.1 Design forces
4.2 Attachment
4.3 Articulation
4.4 Certification
4.5 Identification
4.6 Telescopic drawbars
4.7 Pole trailers
4.8 Additional design considerations
4.9 Welding
4.10 Repair
5 COUPLINGS
5.1 Coupling standards
5.2 Capacity
5.3 Vertical load capacity
5.4 Articulation
5.5 Coupling location
5.6 Safety lock
5.7 Maintenance and inspection
Appendix
Appendix A – Design stresses and design life
Appendix B – Drawbeam and drawbar structural components that are tested and approved to an international standard
Appendix C – Drawbars with vertical loadings
Appendix D – Re-certification
Appendix E – Side force on drawbars without turntable locks
Appendix F – Explanatory notes on the 2007 and 2024 revisions of the standard
Figure 1 – Dimensions of the simple trailer
Figure 2 – Example of a drawbeam identification label
Figure 3 – Examples of couplings and drawbeam assembly
Figure 4 – Example of a drawbar identification label
Figure 5 – Example of a drawbar and attachment
Figure C1 – Coupling forces for a drawbeam with a vertical load
Figure E1 – Tandem-axle set and tri-axle set
Table 1 – Design loads for specified maximum towed mass (MTM)
Table B1 – Minimum D value for a specified maximum towed mass (MTM)
Previous versions
NZS 5446:2024
Online Library subscription information
Online library subscriptions provide a cost-effective solution for organisations of any size to access the latest standards, offering 24/7 access to a personalised catalogue. The service ensures subscribers have have the most up-to-date version of selected standards, incluing automatic updates for any amendments or versions. Pricing is dependent on the chosen standards and the number of concurrent users, with discounts applied from the standards PDF price. For customised subscriptions or further inquiries, contact the Online Library team.