Industry alert: Risk of trailers disconnecting from incorrect coupling and damaged couplings
December 2025
NZ Transport Agency Waka Kotahi (NZTA) is issuing an industry alert to warn the heavy vehicle industry about the risk of trailers becoming disconnected.
Industry alert: Risk of trailers disconnecting from incorrect coupling and damaged couplings [PDF, 625 KB]
Incidents where drawbar trailers have failed to couple correctly have caused them to disconnect or damage the coupling.
This type of failure can happen when coupling dropping pins are blocked by dirt or something else preventing the pin from dropping to the fully locked position.
Regular inspection, maintenance, lubrication and keeping couplings clean will prevent this happening.
Truck tow couplings with a dropping pin must be checked and inspected regularly. Drivers must check the trailer coupling at every connection at least once a day (before driving).
Key points
- Do not use modified or damaged couplings. Look out for release handles which have been bent or shifted from their original position (sometimes referred to as "clocked" on the spline).
- Keep coupling bottom bushes clean and free of debris. Do not drive with the dropping pin in the raised position, it allows dirt and debris to enter the lower pin bush.
For operators
If you operate vehicles with a drawbar:
- Inspect your fleet and check the condition of towing connections.
- Stop using vehicles with a damaged coupling or towing connection.
- Clean dirt or debris from the towing connection before inspection and use.
- Test the coupling and confirm it is working correctly, and the locking indicator is accurate.
- Complete repairs and maintenance before returning the vehicle to service.
- Keep couplings closed (pin down) when not towing, to reduce dirt in the lower pin receiver.
- Drivers must always physically check correct trailer coupling before driving.
For vehicle inspectors
When inspecting a drawbar coupling:
- Check the locking indicator shows the correct pin position (open or locked).
- Make sure the coupling is reasonably clean and the lower bush (where the pin drops) is clean and free of debris.
- Check the release handle isn’t obstructed, damaged, or hitting other components. It must freely travel to the locked pin position.
For certifiers
When inspecting a draw beam and coupling:
- Check the coupling is installed according to the manufacturer’s instructions.
- Check the coupling and locking indicator work correctly.
- Check the release handle isn’t obstructed or hitting other components in all positions. It must move freely to the locked pin position.
For repairers
- Dropping pins must move freely and lock properly—don’t allow anything to block or restrict them.
- Repairs must follow the manufacturer’s instructions and specifications.
- All components must meet the coupling manufacturer’s wear specification/tolerances.
- Make sure release handles aren’t obstructed or hitting components in all positions (locked and open).
- Ensure couplings are clean, especially in the lower bush which locates the dropping pin.
- Lubricate couplings correctly.
- Never allow a vehicle to be operated with an excessively worn or damaged coupling.
- After any repair, test the coupling to confirm:
- it works correctly
- the release handle isn’t obstructed in any position
- the dropping pin correctly locates in its locked position
- the locking indicator correctly indicates pin position and the couplings locked and unlocked status.
Industry alert: Poor nighttime visibility caused by bike racks on some buses
October 2024 | updated April 2025
NZ Transport Agency Waka Kotahi (NZTA) has updated the industry alert warning public transport bus operators of a possible issue with nighttime visibility when bicycles are carried on a front-mounted bike rack.
Industry alert: Poor nighttime visibility caused by bike racks on some buses [PDF, 648 KB]
On some buses fitted with a bike rack, bicycles carried at night can partially obscure the headlamp/s causing a lack of illumination of the road ahead. This is non-compliant with the Land Transport Rule: Vehicle Lighting 2004 (the Rule).
The industry alert provides information on how operators can check if their buses are affected, and what they can do if they find their fleet is affected.
In April 2025 NZTA issued a temporary class exemption allowing daytime-only use of bike racks on urban buses. This is to allow for operators to carry out assessments, implements lighting solutions, and apply for individual exemptions that allow 24/7 use of bike racks.
Land Transport Rule: Vehicle Lighting 2004 (Bicycle Racks on Urban Buses) Class Exemption Notice 2025 - 2025-sl1969- New Zealand Gazette(external link)
Key points
- Bus operators should check if their buses are affected and take actions as necessary.
- Bus operators should refer to the bus lighting assessment and improvement options guidance document.
- Bus operators are responsible for maintaining and operating their vehicles in line with the Rule.
Bus lighting assessment and improvement options
This guidance outlines a standardised lighting performance assessment method, a Reference Line Method (RLM).
Bus operators should use this method to check all bus model and bike rack model combinations for non-compliance. Operators can check if they meet the requirements of the Land Transport Rule: Vehicle Lighting 2004 (the Rule) by using a RLM, and what action should be taken if they don’t meet the requirements.
All buses fitted with bike racks will need to apply for an exemption from the Rule. Guidance on how to do this is in this document. The RLM will determine the details of the exemption.
Bus lighting assessment and improvement options [PDF, 344 KB] (updated February 2025)
Reference line method diagram [PDF, 145 KB]
Industry alert: Risk of cracks in perforated chassis rails
February 2024
NZ Transport Agency Waka Kotahi (NZTA) has issued this industry alert to warn heavy vehicle specialist certifiers and heavy vehicle service providers about the risk of cracks forming in perforated chassis rails.
Industry alert: Risk of cracks in perforated chassis rails [PDF, 737 KB]
Key points for service providers
Heavy vehicle service providers should make sure:
- chassis rails are inspected at every opportunity, especially near load anchor points like log bolsters or container twist locks, and mounting points for other heavy equipment like hi-abs or cranes
- any repairs are completed according to the manufacturer’s instructions, where available
- any modifications meet the applicable certification requirements.
Key points for certifiers
- Make sure the HVEL certification (LT400) for a log bolster attachment confirms the chassis rating remains valid, or a new chassis rating and HVEC certification (LT400) must be issued.
- Consider all conditions of loading in your assessment, including unusual conditions such as side loading from the towing connection or a ‘piggybacked’ trailer.
- Follow good design practice by assessing critical areas, for example avoiding points of high stress concentrations (refer to Appendix B of AS3990-1993 for more information).
Industry alert: Risks associated with trunnion pin type suspension systems
November 2022
NZ Transport Agency Waka Kotahi (NZTA) has issued an Industry Alert for trunnion pin type suspension systems.
Industry alert: Risks associated with trunnion pin type suspension systems [PDF, 650 KB]
The Industry Alert provides information about the risks associated with repair or refurbishment of trunnion pin type rear suspension systems common to many heavy vehicles.
An incident where the trunnion pin was ejected from a heavy vehicle suspension causing fatal injuries was investigated by the Police Commercial Vehicle Safety Team (CVST). The Police investigation and report in 2019 found that the incident was mainly caused by the trunnion pin breaking. In addition, the overhaul techniques and replacement parts used during a recent refurbishment of the truck’s rear suspension assembly were of concern.
The industry alert is aimed at heavy vehicle service providers and heavy vehicle operators to ensure all repairers of heavy vehicles are aware of this issue.
Key points
Service providers and vehicle operators should:
- understand the risks of reconditioning this type of trunnion pin suspension system
- only use Original Equipment (OE) trunnion pins and trunnion housings purchased from a reputable supplier for this type of suspension system
- ensure that these suspension units are repaired according to the manufacturer’s instructions by suitably qualified people.
