erving industries such as quarrying, civil engineering, waste management, demolition and environmental services,
McQuillan Quarries relies on an asphalt plant mixer which it uses to mix aggregates from the quarry with bitumen to create durable and reliable road surfaces across Northern Ireland. For over a decade, however, the gearboxes on
the mixer were often lasting as little as a year and a half before failing, resulting in significant costs, including expensive replacement parts, as well as extensive labour and downtime.
A Bonfiglioli 300 Series heavy-duty planetary gear unit was specified
In addition to this, the gearbox system’s two shafts were causing problems due to misalignment and uneven load distribution, which led to excessive wear on bearings and other components. “We were losing faith in the existing setup
due to the high rate of failures and the extensive stock of left- and right-sided gearboxes we had to maintain just to stay operational,” commented Colin Mitchell, general manager at McQuillan Quarries. Needing a whole new design engineering concept McQuillan Quarries turned to Technidrive to engineer a solution that could handle the high-impact load of mixing bitumen and stone.
Technidrive began by assessing the mixer’s needs and the constraints of McQuillan’s production schedule. Several considerations shaped the final approach: • First, the new system needed to withstand substantial shock loading from each three-tonne batch drop, a major stress point for the previous gearboxes.
• Second, the existing configuration had limited space for additional equipment, so Technidrive’s solution required precision engineering to fit seamlessly within the existing footprint.
• Third, to reduce the downtime associated with frequent gearbox replacements, Technidrive aimed to design a system with a life expectancy of ten years or more.
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The company looked at a number of options to meet the requirements. One possibility was to upgrade the existing gearbox to a heavier version, but that didn’t address the shortcomings of the current system such as excessive wear. Another idea was to use a single gearbox to drive synchronised gears on the shafts, but this idea would potentially concentrate stress and lack the flexibility needed for reliable operation. Technidrive’s chosen solution, however, was to
implement two planetary gearboxes that utilised the existing motors to independently drive the shafts. Custom synchronising gears were added to keep the shafts aligned, creating a robust solution capable of handling the system’s demands while delivering maximum benefits. “We designed the planetary gearbox
arrangement to absorb impacts more effectively and minimise stress on the system,” said Andrew Ritchie, technical sales manager at Technidrive. “Our goal was to provide a solution that wouldn’t just solve the immediate issues but would ensure long-term reliability.”
Changes to a long established production process or equipment setup invites risk for manufacturers, and McQuillan’s team were concerned that the new planetary gearboxes design wouldn’t work.
“It wasn’t an easy decision,” remarked
Mitchell. “But we wanted a system that could handle the shock loading and last for years. This planetary gearbox setup had the highest service factor and shock-loading capabilities.” The new system was installed over a long
weekend to minimise production interruption, with the key challenge being to ensure the new system could fit within the existing plant configuration, especially since space was quite limited. The selected gearbox for the new solution was a Bonfiglioli 300 Series heavy-duty planetary gear unit. This series is noted for its durability and adaptability to high-impact applications. This was used with the existing motors and switchgear. The entire installation was smooth, with only minor adjustments, and has since proven exceptionally reliable. “Technidrive played a crucial role in this by
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