A series of large tipper (dump) trucks were refused entry into an Australian coal mine recently as they did not comply with Australian standards for safe operation of rear dump/tipper trucks.
Independent Transport Consulting Hydraulics (ITCH) was employed to evaluate, recommend, supply, install and commission a hydraulic valve system that would enable the mine to comply with the Australian Standard and OH&S requirements.
According to the company extensive market research was conducted and the Mathers Tipper Safety Valve was found to be the only valve system that met the Australian standard requirements.
Mathers employee Vaughan McColl said the tipper safety valve was the only valve that conformed to the requirement of controlled rate of descent of the hoist cylinder.
“Being pressure compensated it provides a controlled rate of descent, regardless of load,” he said.
An isolation valve that also conforms to the Australian standard and the Department of Primary Industries Mine Safe operations guidelines was fitted. The valve prevents accidental actuation of the hoist cylinder main pilot lowering valve when maintenance work is being carried out, a cause of many accidents.”
According to Vaughan, when truck chassis twist with hoist cylinders is in the raised position, ‘JamLock’ occurs and oil drains from the cylinder. When realigned, the tipper tray then comes crashing down, potentially causing accidents and damage.
“The tipper safety valve senses the low pressure ‘Jam Lock’ situation and retains oil volume in the hoist cylinder, ensuring safe, controlled lowering when realignment occurs,” Vaughan said.
Hose burst protection under load and a special safe, manual lower feature, are also incorporated in the tipper safety valve design.
The tipper safety valve kits come with a circuit diagram operation plate for mounting on the truck, and conforms to Australian standard AS:14 18.8.