Brake system maintenance – rubber tyred vehicles

Background

Many high potential incidents over recent years at Queensland mines and quarries involved brake systems on highway and industrial trucks, and on heavy earthmoving equipment.

Some have resulted in serious injury, or even death, and contributing factors included:

• using equipment not fit for purpose, such as on-highway trucks not designed for mine site terrain, and overloading
• not considering site operating conditions, such as steep grades, operating speeds, operating cycles, or site layout
• poor brake system maintenance and performance monitoring
• continuing to use equipment even after poor brake performance has been detected
• lack of information and training on brake operation and maintenance requirements for operating / maintenance personnel.

Equipment operation and brake system maintenance strategies

Correct brake system functioning depends on the condition of system components, which in turn depends on the quality of the maintenance, so any brake system maintenance strategy should focus on detecting and rectifying a defect before it results in a loss of brake function. The ultimate loss of brake function (e.g. failing a brake performance test) should not be the trigger for inspection and rectification.

Brake system maintenance strategies should initially be based on the Original Equipment Manufacturer (OEM) recommended maintenance programs, and on condition monitoring, inspection and testing schedules. OEM stipulated operating procedures and repair techniques help ensure brake system integrity is not compromised.

The OEM information should be stored, maintained, updated and be readily accessible by relevant personnel, whether it be hard copy, electronic copy, or on-line based systems.

To ensure that risks arising from site conditions, operating parameters and duty cycles are within acceptable limits, and as low as reasonably achievable, additional testing and monitoring might be warranted. In fact, the risk assessments aimed at improving brake system reliability should consider anything that could affect the safe operation of equipment, including maximum loads, operating speeds, operating grades, effects of heat fade, component failure, and loss of pressure.

Controls needed may include more frequent component inspections for wear/damage, and regular brake performance verification techniques, such as Dynamic Brake Testing (DBT) and thermographic temperature profiling, to detect poor performance.

Note that a positive DBT result doesn't necessarily verify brake system integrity or confirm the system has been maintained to OEM recommendations. It only indicates the brakes were effective at that time of testing.

In introducing a DBT program, the risk assessment to determine appropriate controls should consider, but not be limited to:

• OEM consultation on any deviations from the stated recommendations.
• Applying relevant brake performance testing standards or appropriate industry practice.
• Site facilities and limitations relating to surface, space, and controlling equipment in case of brake failure during testing.
• Variations in test methodology and acceptance criteria for different equipment types and categories - refer to AS 2958.1:1995 'Earth-moving machinery – Safety, Part 1: Wheeled machines – Brakes'.
• Reliability of the DBT test instruments.
• Applicability and integrity of the standards, procedures and methods used to interpret the results.
• Training and competency of personnel conducting the tests.

Industrial trucks and load shifting equipment (forklifts, mobile cranes etc)

Inherent instability and lack of traction of forklifts and cranes on mine sites, particularly on ramps and slopes, present a challenging risk management task. Recent incidents involving these show that the importance of effective parking and travel brakes is often overlooked. Users should ensure that operators understand the brake system design limitations, and that brake system monitoring, inspection, testing and maintenance are appropriate for the risks in particular applications.

The Australian Standard AS 2359.13-2005 'Powered industrial trucks Part 13: Brake performance and component strength' provides guidance on methods for assessing and testing the performance and components of brakes fitted to industrial trucks with rated capacities up to, and including, 50 tonnes.

Safe forklift operation on gradients largely depends on the type, size and design of the forklift. Ask the OEM if you're unsure of the braking system's performance capabilities.

Australian Standard AS 2359.2-2005 'SAA Industrial truck codes Part 2: Operation' provides guidance on requirements for the operation, maintenance, repair and modification of industrial trucks.

Recommendations

Persons obligated under the Mining and Quarrying Safety and Health Act 1999 to manage risk at a mine in relation to plant have specific obligations under the Mining and Quarrying Safety and Health Regulation 2001, Part 10 Plant generally. They should also ensure that:

• the site Safety and Health Management System requires operating, monitoring and maintaining brake systems according to OEM recommendations, as a minimum,
• the condition of brake system components is monitored according to OEM's recommendations, reducing the likelihood of catastrophic failure and ensuring they continue to function as intended,
• brake system performance is tested according to OEM's recommendations, to reduce the likelihood of reduced performance during operation, and to ensure continued performance as intended,
• operating and maintenance personnel can access OEM operating and maintenance manuals at site,
• braking system repair, monitoring, inspection and testing records are readily available at site,
• operators and maintainers are trained in the relevant aspects of braking systems,
• safety critical aspects of equipment operation, including emergency braking systems, retarders and other controls available in the event of engine failure, (e.g. accumulators), are incorporated into the operator training and assessment processes with appropriate input from competent maintenance personnel,
• operating and brake maintenance practices for contractors' equipment are not inferior to the equipment maintenance practices adopted by the principal,
• contractors' equipment is not allowed to operate on site unless maintenance and testing records are checked to verify the integrity of brake systems,
• brake maintenance, including processes used for contractors' equipment, is regularly audited for effectiveness, and
• if OEM manuals are unobtainable (e.g. due to the age of equipment), prepare manuals so effective brake system operation and maintenance strategies can be established, using people with appropriate skills and technical expertise to facilitate the process.

Authorised by Rob O’Sullivan - Chief Inspector of Mines

Contact: minesafetyandhealth@dnrm.qld.gov.au

Issued by Queensland Department of Employment, Economic Development and Innovation