Team members at Komatsu’s Parkhurst facility in Central Queensland have developed an innovative solution to significantly improve the serviceability and maintenance of underground coal mining shuttle cars.
Shuttle cars have been used for the transportation of coal from the continuous miner to the conveyor system in the underground coal industry for well over 50 years. Prior to the installation of service jacks to shuttle cars becoming an industry standard many years ago, maintenance tasks were frequently undertaken using what were often precarious methods of supporting the shuttle car.
Today’s shuttle car now incorporates as standard fitment four hydraulically operated service jacks, two at each end, designed to raise the car for maintenance, including changing of the wheels when required. A key requirement when the shuttle car is raised, is to ensure that the service jack cannot retract under load, which would result in the shuttle car lowering back to the ground. To prevent this happening, “safety collars” are installed to the extended cylinder rod to prevent inadvertent retraction of the cylinder.
There have been a number of designs of safety collars over the years, all with two main issues: weight, and accessibility for installation, particularly at the front end of the shuttle car. Safety collars can weigh up to40 kg, which raises a major handling issue during the installation process. To reduce the handling issue, several shuttle car operators have sourced safety collars made from composite materials which are significantly lighter than traditional steel products. However, the downside to these composite safety collars is their cost and longevity. Typically, composite collars require replacement every 12 months due to the breakdown of the high-tech materials used and four per shuttle car become an expensive option.
Enter Komatsu’s Parkhurst engineering team, based near Rockhampton, in Central Queensland, in developing an alternative, more user-friendly service jack design. Under direction from Francois Nortje (Senior Engineer), Jianjun Han (Continuous Mining Systems (CMS) Haulage Engineer) set out to develop a concept for a new service jack. The concept was reviewed by the CMS Haulage team and met with extremely positive reviews, along with the direction to proceed to complete the engineering design.
The design and development phase included the engineering calculations, Design Failure Mode and Effect Analysis (DFMEA) and material selection, with the main criteria being for the new service jack to be retrofittable, with minimal modifications required to existing shuttle cars. In conjunction with the design and development process a patent application has also been submitted to protect the design.
The new design consists of an inverted cylinder which operates inside an outer housing; the cylinder rod is fixed, and the cylinder body extends and retracts. When the cylinder is extended to raise the shuttle car, a “staple” is inserted into a receiving block – an integral part of the outer housing – locking the cylinder in the extended position preventing inadvertent retraction of the cylinder and lowering of the shuttle car.
The “staple” is inserted and locked in the installed position with the insertion tool (similar in design to a car jack handle). This new system offers major handling benefits: the “staple” weighs just 2 kg, the insertion tool also weighs 2 kg and both can be easily stored on the shuttle car in specially designed storage devices.
The new service jack design has been widely presented to our customer base and the response has been very encouraging, with all extremely impressed with the design from both the maintenance and EHS perspectives.
The first new shuttle cars (three units) fitted with the new service jack design have now been delivered to a Central Queensland site and were very well received by both the management team and maintenance personnel.
A further three shuttle cars are now in production and have the new service jacks included in the machine specification.The new design of service jacks will become the standard fitment on all new Komatsu shuttle cars sold into the Australian market.
The challenge ahead is to secure an increased market share in the shuttle car overhaul business, and further enhance the population of these service jacks by retrofitting to existing shuttle cars.
Congratulations to Jianjun and Francois for their outstanding achievement on the design and roll out of the new service jack.