Print Download PDF

Technical bulletins (CoF)

9 Park brake inspection and 4085D requirements


VIRM reference

Heavy vehicles 8-1: Service brake, parking brake and heavy vehicle emergency brake

Background

The 4085D Operator statement of compliance with maintenance requirements for parking brake assemblies form is used by a heavy vehicle operator to confirm a powered heavy vehicle’s parking brake assembly has been inspected/serviced by a technician in last two years and is in good working condition. The need for this inspection has come about due to a number of run-away trucks that have led to a fatal or serious injury crash after the parking brake has been applied.

The issue has been traced to the parking brake application valve beside the driver’s seat on many truck, bus and motorhome vehicles. The valve wears out internally through dust and moisture ingress over time and can cause the valve detent to stick in the neck portion and not fully engage with the lock. As the driver gets out of the vehicle the valve can be knocked or on occasions get caught in the driver’s clothing releasing the lever.

There is also evidence that carden shaft brake assemblies have caused some trucks to run away even when the lever is applied. This is due to a number of factors including a lack of maintenance that reduces the ability of the brake to hold the vehicle and load, especially in steep inclines and where the lever feels fully applied but resistance in the linkages reduces the application of the brake.

This bulletin has been produced to supplement information provided to the repair industry and should be considered in inspecting all parts of the parking brake system.

Parking brake inspection

What are the indicators that might make a vehicle inspector doubt the condition of a parking brake assembly?

A parking brake is generally serviceable (except for some sealed parking brake valves) with items that are susceptible to wear, degradation and ingress of dust and dirt.

Not all parking brake assemblies are easily accessible but signs that may point to no recent maintenance include:

  • rusted bolts, screws, clevis pins or linkages which activate the brakes
  • dust, dirt, seat foam or general rubbish around the lever assembly
  • excessive resistance in applying the parking brake
  • a lack of feel from the detent or lock position when applying the lever of an air parking brake valve.
Are there any parts within the assembly that are more prone to cause problems than others?

The risk is more with the age of the vehicle (particularly older vehicles that have not been regularly serviced) and those working in dusty operations such as concrete mixer trucks and quarry trucks.

Pay particular attention to the application lever and any detents, ratchet or other mechanical locks designed to hold the lever in its applied position.

Are there specific makes/models that should be paid close attention to?

Vehicle inspectors should pay attention to all parking brake assemblies. All makes or models should be treated equally. As mentioned above, vehicles working in dusty operations such as concrete mixer trucks and quarry trucks are higher risk.

The Transport Agency has published safety alerts covering some Nissan trucks that require 12-monthly parking brake checks and maintenance.

4085D requirement scenarios

If a vehicle inspector doubts the maintenance of a parking brake assembly, they can request that the 4085D form be presented to provide proof of inspection/servicing in the last two years (once the vehicle exceeds two years from date of first registration in New Zealand, or every CoF from date of first registration if entry certified as a used vehicle).

If an operator does not have a valid 4085D to present, then the vehicle inspector can issue a 28-day permit instead, to allow the operator to have the parking brake maintenance carried out and get a 4085D completed.

If you request a 4085D because you doubt the parking brake maintenance, but an operator says that the parking brake was recently serviced, you can tell the operator they can get the service agent to fill in the form with regard to the last service – they don't have to get the servicing done on the parking brake again.

When do you need to ask the operator of a powered heavy vehicle (a heavy truck, bus or motorhome above 3500kg) for a 4085D?
  • The vehicle passes the certificate of fitness (CoF) for parking brake performance (i.e. passes a roller brake test or stall test) and passes all other CoF requirements, but the vehicle inspector (VI) has doubts about the parking brake maintenance so can request a completed 4085D form and issue a 28-day CoF permit.
  • The vehicle fails the CoF test for parking brake performance under the reasons for rejection. This requires the VI to fail the vehicle and request a 4085D form.
  • The vehicle passes the parking brake performance test and fails on another CoF item and the VI has doubts about the parking brake maintenance so must fail the CoF and also request a 4085D form is required.
When do you NOT need to ask the operator of a powered heavy vehicle for a 4085D?
  • The vehicle passes its CoF for parking brake performance (ie it passes a roller brake test or stall test) and passes all other CoF requirements and the VI has no doubts about parking brake maintenance so can issue full CoF.
  • The vehicle passes the parking brake performance test and fails on another CoF item and the VI has no doubts about the parking brake maintenance. The VI fails the CoF for the other item(s) and no 4085D form is required.

Page added 21 February 2020 (see amendment details).