With the spotlight on safety in mining, the new prototype Air Rail Switch from Torre Industries’ pneumatic automation business, Pneumax is set to reduce risk in underground rail traffic.
Pneumax has joined forces with power electronic engineering technology leaders, Battery Electric, to incorporate a fail-safe design into a uniquely assembled South African product that will ensure safe rail switching in high risk areas. “Up to this point, mines have seen rail track changeover safety as a real problem with no fail-safe solution,” says Pneumax national sales manager, Eugene Van Der Lith, “This prototype is specifically designed to protect the health and safety of mineworkers, employing the latest in electrical engineering and pneumatics to work towards best practice in the mining industry.”
In the case of rail accidents and fatalities, the common cause is an unexpected switching of lanes to the wrong track, either by human error – manually misusing the metal industrial crowbar known as a ‘gwala’ in South African mines – or when components have deteriorated and failed inside switch devices. One of the worst rail mining disasters on record was in 1995 when 104 miners lost their lives at Vaal Reef when an underground locomotive carriage fell down a lift shaft and landed onto a cage loaded with night shift miners.
This prototype with its control box replaces the need for a gwala. It overcomes the darkness and noise factor of mines with its in-built visual and audio safety features. In addition it has an emergency air shutoff valve to quickly stop any moving parts, thereby minimising the risk of injury.
“Pneumatically, we knew that we had a viable safety concept for the mines. Applying a non-perishable reservoir of air to a rail switch creates a fail-safe design,” says Van Der Lith. “The advantage of Pneumax partnering with mining industry specialists, Battery Electric is that we have created an integrated concept that features RFID controlled access via a card reader, proximity detection, and warning systems, all backed up by expertise in pneumatic actuated switching.”
For safety, only an operator with a licensed RFID access card can choose to open or close the Air Rail Switch by inserting the RFID access card and selecting the open/close button switch. Mechanically, a pneumatic actuator is used to move the switch, which changes the direction of traffic on the rails. The air is fed in from the mine’s airline and collected in a reservoir which is used to feed the system in the event of air loss. Pressurised, filtered air is then used to keep the rail switch in the open (default) position in a critical situation. For instance, in cases where the switch had not been activated, or if there is a loss in power or air to the system it will remain in an unchanged position. The inbuilt contingencies of the switch will keep rail traffic on track even if the licensed authorisation card has been removed.
Safety is the sole purpose of the switch, and the system design requires the operator to move away from unsafe environments before operating on the moving components of the product. When an RFID card is inserted, flashing lights are activated to indicate possible operation. During the mechanical movement of the rail switch, a warning buzzer is used to alert locomotive operators of its position as they approach. And while the switch is moving to change tracks, creep speed control is automatically applied to any locomotive in close proximity.
“The default position is also known as the fail-safe position and locomotive traffic is controlled in the direction of the straight track,” explains Van Der Lith. “Importantly, the Air Rail Switch is completely free of electricity – an added safety feature that eliminates the hazard of water on underground rails and makes the Air Rail Switch ideally suited for use in harsh mining environments.”
Standard equipment includes: a rail switch, control box, RFID system and indicators (flashing lights for visual signalling, and a buzzer for audio signalling. Every pneumatic component of the switch is locally stocked and replaceable.
The team is now in test phase, working together with Lonmin and mine engineers for approval, and in the process of writing a risk assessment. A complete safety pack will be drawn up.
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