AMSJ » Braking system faults – RETRACTED
Plant Maintenance Vehicle Safety

Braking system faults – RETRACTED

Houston we have a problem

The contents of this story have been retracted following a series of complaints by Anglo American to AMSJ management regarding the speculative and premature nature of the story. While AMSJ re-iterated to Anglo American that the information provided to AMSJ had been verified from independent sources and was published in the interest of informing the industry of a potentially hazardous condition which had claimed the life of a mineworker, we have chosen to withdraw the content on the basis of Anglo’s request.

Lisa Clifford, Anglo American’s media representative stated to us “First, I must reiterate that the safety of our people is Anglo American’s first priority and it is out of care for our people and their families that we raise concerns about the speculative and premature claims made in the article you have published. We also take our broader leadership within the industry on matters of safety extremely seriously, and we participate in a number of forums including the Queensland Mines Safety Conference, where we actively share our learnings, innovations and other information to promote broader improvements in the sustainability area.”

Ms Clifford also stated, “The publication of a story that is based on premature speculation in place of established fact is unhelpful in promoting safety in the industry – the very core of what you claim your publication aims to do.” 

Anglo American has fully cooperated with these investigations, which remain ongoing, and continues to do so. Given the investigations are not yet concluded, again, our concern with your story is that its claims are speculative only and any reference to potential contributing factors to Bradley’s cause of death are premature, particularly given the cause of death is not yet known.

AMSJ management understands Anglo American’s concerns and has chosen to withdraw the contents of this story at this time, however, we will vigorously continue to follow any updated information on the story as it arises and will ensure that any and all findings from formal investigations are communicated promptly to the industry.

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Braking systems on underground equipment (particularly custom built equipment) should be reviewed

The Queensland Department of Natural Resources and Mines has issued a general statement in May 2019 regarding braking systems.
The Department stated that there have been several serious incidents in Queensland mines involving brake failure and has made a number of comments in respect to mining equipment braking systems (below).
  • Investigations of the incidents have identified multiple contributing factors.  However, several factors relating to braking system engineering and maintenance have been identified.
  • Contributing factors specifically related to braking systems include:
    • Pre-start checks:
      • Pre-start checks and findings not documented.
      • Safety critical components such as system accumulator pressures not checked prior to equipment use.
    • Defect management:
      • No formal system in place to record defects, actions taken to address defects or communicate actions to workers.
      • Plant continues to be operated with known defective braking systems.
    • Foreseeable events:
      • The shutdown of the vehicle engine renders the steering system very difficult to operate and hydraulically operated implements, including access components, may not be able to be lowered to ground level.  Mine procedures for safe parking, particularly on grades, may not be able to be complied with in such situations.
    • Maintenance systems:
      • Maintenance and operations manuals not readily available to operators or maintainers.
      • Recommended OEM maintenance checks on brake systems not being completed.
    • Brake system components:
      • Accumulators in braking circuits have been found to be defective.
      • Air separators bypassed.
      • Air circuit check valves inoperable and not installed in the correct orientation.
      • Brake system air leaks resulting in defective brakes.
      • Operation of brake circuit components relying on specific sequencing and timing found to not be within specification.  This may have resulted in undetected worn and inoperable braking components.
    • Modifications to brake circuits:
      • Brake circuit integrity significantly affected by small seemingly insignificant hose/circuit changes such as bypassing what is effectively a critical component.
    • The consequence of failed components in the brake system:
      • A failed check valve allowed bidirectional flow in and out of the service brake circuit. This didn’t adversely affect the service brake until an air leak external to the service brake drained air from the service brakes rendering them inoperable.
      • Inadequately pressurised brake system accumulators could not provide sufficient system pressure for effective braking when the engine stalled.
    • Hidden failures:
      • Test procedures not actually testing the circuit or critical parts of the brake circuit masking failed components.
      • An investigation found that the tests carried out to check the park brake in fact only checked the service brake.
    • Version control of technical information:
      • Brake circuits not updated to the latest OEM or approved brake system design.  A safety critical upgrade appeared to have not been implemented.

Image: Queensland Department of Natural Resources & Mines website

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