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The design requirements met by PJB cover rollover protection, falling object protection, automatic reversing alarm, roof mounted flashing lights, seat belts and or passenger restraints, fail-to-safety brakes, auto or manual fire suppression systems, pinch point access management, automatic immobilisation and a range of management processes.
PJB were approached by several BHPB mines which requested full rollover protection and falling object protection, forward facing seating and lap-sash, inertia reel and seatbelts.
During the design PJB adapted the requirements of AS2294 for the design and testing of the rollover and falling object protection. In the course of testing for rollover protection compliance, forces were applied laterally, vertically and longitudinally.
For falling object protection a large steel ball was dropped a prescribed distance onto the largest span of the roof structure and it was tested there was no encroachment on the deflection limit volume.
“Among the many engineering challenges in the design was the maximisation of structural integrity while minimising the mass increase in the process,” PJB managing director Phil Berriman said.
PJB overcame this challenge with flying colours by meeting all the test criteria and only increasing the gross mass of the vehicle by 20% compared to a standard machine.
While a seventh vehicle has been ordered from PJB, it is uncertain whether other coal companies will adopt similar protocols.
“Essentially what has happened is BHPB have raised the bar and when somebody does that – particularly when it is driven by a big industry player - it creates some interesting issues from an occupational health and safety point of view. Whether other industry players think it is necessary or whether they think it is over the top will have to be addressed on an industry basis,” Berriman said.
Berriman said it will be dealt with when the New South Wales Committee meets to re-write the guidelines for design and testing of free-steered vehicles in underground coal mines (MDG 1). The meeting is yet to be scheduled.
