Park brake failure - truck rolls away

Mine type

All mine types

Incident

An unattended, partly loaded bulk explosives truck was parked with its engine running. The driver had applied the park brake before disembarking and was walking away from the truck when he noticed it moving. While the truck was rolling away he climbed back in the cab and stopped the truck by applying the foot brake. The truck had travelled about 20 metres and ended up with its front wheels suspended over the edge of a 2.5m drop.

Equipment

Iveco Acco 2350G truck.

Hazard

Uncontrolled movement of a vehicle.

Cause

The park brake lever did not lock into position when applied. When the driver closed the door as he left the cabin, the vibration jolted the lever into the release position.

Comments and recommendations

• The park brake lever is designed to be locked into position by a detent (a spring-activated pin that automatically drops into a catch hole). Tests showed that the park brake could be 'applied' while the pin remained unlocked. A slight jolt to the lever was all it took to release the brake.
• The truck's 'brake not applied' alarm is activated by a sensor that monitors the position of the lever rather than the status of the detent.
• Post-incident testing revealed that the alarm worked only when the ignition was on.
• The driver's understanding of the truck's braking system was inadequate.
• Climbing into the cabin of a runaway vehicle is dangerous and can result in serious injuries, or worse.
• The designated area in which the truck was parked was not suitably designed to prevent vehicles rolling away in the event of a park brake failure.

Truck operators ensure:

• drivers of trucks with similar park brake levers are aware of the design weakness and that they double-check the lever is locked in position when parking
• the 'brake not applied' alarm works regardless of the ignition position
• risk controls—including parking procedures and the design of designated parking areas—adequately reduce the risk of vehicles or mobile equipment rolling away.

Manufacturers and suppliers of trucks with similar park brake levers:

• review the design of the lever's locking mechanism to reduce the risk of similar failures, and
• improve the alarm systems so that they can detect whether the levers are locked in position.

Authorised by Phil Goode - Regional Inspector of Mines, Southern

Contact: minesafetyandhealth@dnrm.qld.gov.au

Issued by Queensland Department of Mines and Energy