A loaded CAT ADT lost engine power whilst travelling up a ramp. The secondary braking system failed to operate, leaving the ADT with no brake pressure, resulting in the truck rolling back down.

On investigation, the brake accumulators were found to have reduced pressure within the nitrogen charge.

The incident investigation has highlighted inconsistencies with the maintenance regimes for the CAT ADT brake accumulators.

This issue may be common across a number of the CAT operated fleets within the UK.

Please see attached pdf of technical bulletin from Finning.

• Perform an accumulator nitrogen gas recharge every 2000 SMU as part of the scheduled service program.


• Wherever there is doubt that the 2000 SMU routine has correctly considered the accumulator nitrogen pressure, it is recommended that these should be checked for nitrogen pressure as a matter of urgency.


• Daily Service Brake checks should include an Accumulator Functional Check as per the manufacturer’s recommendations. This requires brakes to be tested with the engine turned off after a short run to charge the system.