Summary: The operator of a haul truck was lowering his tray after dumping a load when the tray suddenly slammed down to the bump stops. The lower retaining bolts of the left hand cylinder retainer may have failed, causing the cylinder to fall off when lowering. An on-site audit of other haul trucks revealed more loose bolts on the cylinder retainers.
Recommendations to industry: Mine operators should review the maintenance programs associated with haul trucks according to the original equipment manufacturer (OEM) recommendations. Maintenance and inspection frequency may need to be increased depending on the site’s environmental or operating conditions. Relevant OEM information for torque settings, lubrication or thread locking compounds and lock washers should be provided to maintenance personnel. Torque wrenches used for servicing should be calibrated.