Potential Hazard Notice: Inadvertent Park Break Release

This notice provides awareness of a potentially hazardous situation involving Caterpillar 769D haul trucks manufactured in the late 1990s with serial numbers identified below:
 
Make: Caterpillar
Model: 769D Haul Trucks
Serial Numbers: 5TR00001 – 5TR00504

Caterpillar 769D Haul Truck CAT 769D haul truck’s position relative to CAT 400E articulating truck when park brake released

A miner was seriously injured when he exited an idling CAT 769D haul truck and began a pre-shift examination of a Caterpillar 400E articulating truck that was parked directly in front of the CAT 769D haul truck.  The park brake on the CAT 769D haul truck unexpectedly released causing it to roll forward pinching the miner between the bumpers of the two trucks.  Equipment operators must only pre-shift the equipment they are operating.  The park brake on the identified CAT 769D haul trucks must be properly applied by placing the manual park brake switch in the “ON” position before the machine is shut down.  If the manual park brake switch is not applied or the switch remains in the “OFF” position before shutdown, a spring mechanism will automatically apply the park brake as the air pressure bleeds off to a set pressure.  This creates a potentially hazardous situation when the haul truck is started again.  As the air pressure builds up and reaches the system release pressure, the spring mechanism will automatically release the park brake resulting in a potential runaway situation.  Many haul trucks are designed with a safety feature that prevents the trucks from starting unless the park brake is applied.  Unfortunately, the identified CAT 769D haul trucks do not have the additional safety design and the trucks will start when the park brake is NOT applied or the manual park brake switch is in the “OFF” position.  The equipment operator’s failure to properly apply the park brake by placing the manual park brake switch in the “ON” position was a contributing factor in the described injury accident. 
 
RECOMMENDED ACTION:
 
In an effort to prevent similar accidents, it is recommended that, during routine inspections, inspectors should attempt to locate any identified CAT 769D haul trucks having the specified serial numbers.  The inspector should provide notice to the mine operators and affected miners regarding the potentially hazardous situation and “WARN ALL CAT 769D HAUL TRUCK DRIVERS TO ALWAYS APPLY THE PARK BRAKE BY PLACING THE MANUAL PARK BRAKE SWITCH IN THE “ON” POSITION WHEN PARKING AND/OR IDLING.”  Additionally, inspectors should ensure that mine operators provide adequate task training that emphasizes adherence to the manufacturer’s recommended procedures.  Proper starting and stopping procedures are outlined in the Operation and Maintenance Manual (SEBU 6902) for the Caterpillar 769D Haul Truck.  The attached files contain excerpts from the above referenced Operation and Maintenance Manual (OMM)