Cardan shaft park brakes (also known as driveshaft park brakes) are fitted to many small to medium trucks and a small number of passenger service vehicles.
They are designed to hold the vehicle and its load but have limitations which can lead to a vehicle rolling away.
There have been several incidents where the Cardan shaft park brake has failed and the vehicle has rolled away. In the last 10 years four of these incidents have resulted in fatalities, and we are aware of other unreported incidents.
A Safety Alert has been issued about how and why these brakes can fail. This sheet can be downloaded and supplied to vehicle owners and drivers.
Safety Alert: Cardan shaft park brake failures [PDF, 290 KB]
It is important that owners and drivers understand how these park brakes are designed, how they function and how they should be used. Mechanics must be able to correctly diagnose, maintain and adjust these systems to the manufacturer’s specifications.
On this page, you can find out more information about these park brake types, how to maintain them and how to operate them safely.
Cardan shaft park brake units are relatively simple in construction however safety risks can result from a lack of understanding about how to operate and maintain the brake correctly.
Cardan shaft park brakes use a foundation brake system, generally a single drum brake unit mounted to the gearbox housing. This acts directly on the driveshaft of the vehicle to provide the park brake function.
This type of park brake system brake usually consists of:
Owners should also make sure that:
The park brake must be fully engaged to the manufacturer’s recommended setting. The park brake lever may require more force than a driver is used to, especially if they don’t drive a vehicle with this type of park brake regularly.
If the weight of the vehicle is increased through loading, the amount of braking initially applied may not be enough to hold the heavier vehicle and it may roll away. These types of vehicles are designed to carry heavy loads and when loaded the weight may be over double the unloaded weight.
Don’t engage the park brake while the vehicle is moving at speed as this may damage it. This damage is unlikely to be obvious. Please note, when the vehicle is tested on the Roller Brake Machine the rollers are moving very slowly (3kph). This is not considered enough to damage the brake in any way.
The location of Cardan shaft brakes makes them susceptible to contamination, especially from a leaking gearbox output seal. Contamination degrades the effectiveness of the brake and this will not be visible.
Keeping to the maintenance schedule and adjustment techniques recommended by the manufacturer will help the brake’s performance. Likewise, inadequate maintenance and poor brake adjustment will substantially degrade the performance of the parking brake system .
The key to an effective Cardan shaft park brake performance relies on keeping to the maintenance schedule and adjustment techniques recommended by the manufacturer. Remember that this park brake is a separate unit and not connected to the service brake system.
Poor park brake performance due to wear, misalignment or damage of the brake mechanism will lead to low clamping forces available to hold the vehicle. Poor brake performance due to contaminated friction material (dirt, grease etc) getting into the system will lead to a loss of friction between the brake components. Poor brake performance due to incorrectly adjusted components will lead to a low application force and poor friction between the brake shoe/pad and the brake drum/disc.
We recommend you have this work completed by a heavy vehicle service provider or qualified technician. However, this information may be useful for large operators with in-house service personnel.
Important information for servicing Cardan shaft park brakes [PDF, 317 KB]
Cardan shaft park brakes are tested for a certificate of fitness (CoF).
As of 1 December 2022, the CoF test for vehicles with Cardan shaft brakes is conducted using the roller brake machine. The test will apply to most classes of vehicle with Cardan shaft brakes. For more information, refer to the NZ Heavy Vehicle Brake Test Protocol(external link)
CoF requirements will also be updated to make it mandatory to have a warning sticker displayed in the cab of vehicles with Cardan shaft brakes from 1 April 2023. These stickers will be applied by testing stations free of charge when vehicles are presented for their CoF. Vehicle owners do not need to source their own stickers.
Cardan shaft park brake – Testing in roller brake machines - technical report N21030 - June 2021 [PDF, 1.4 MB]
Cardan shaft park brake – Testing in roller brake machines - technical report N22023 - March 2022 [PDF, 1.1 MB]
It is the owner’s responsibility to ensure the park brake is kept in good condition through maintenance. Owners and drivers should not assume that a current Certificate of Fitness (CoF) ensures the brake will be fully operational in all circumstances.
If your park brake fails the test you may be asked to have the brake serviced and to supply a statement of compliance (4085D form) prior to submitting the vehicle for a re-test.