Moving up through the gears

Thames Water has replaced Varatio Strateline gearboxes with Brevini multi-stage planetary gearboxes on bridge scrapers at Maidenhead WwTW. The planetary units offered increased radial load and torque transmission ratings compared to their predecessors, and were easily retrofitted. The cost of a direct replacement from Brevini significantly undercut the cost of refurbishing the originals or fabricating new bridgework to accommodate another gearbox design.

The Strateline units had reached the end of their service life and site maintenance engineers were faced with the cost of refurbishing an obsolete model or structural fabrication work to adapt the bridge for a new gearbox.

Through a framework agreement for the supply of gearboxes, BSL Brammer was contacted for advice, the recommendation to employ a Brevini Planetary solution was welcomed as it required ‘no engineering’ by the customer in order to make the gearbox fit.

Jon Snaith, General Manager of Brevini UK, visited the site to assess the mechanical requirements and the physical limitations before a solution was assembled. A Brevini three-stage planetary reduction gearbox was selected based upon archive data on the Varatio Strateline.

In order to reproduce the mountings of the Strateline, a bracket was designed which bolted on to the planetary gearbox and had identical mounting bolt hole patterns to the old gearbox.

The solution means the original mounting and bridgework, which is sound, can be retained and the new gearbox fitted without any alterations. This was important for Thames Water as the company employs a ‘no engineering’ policy where possible on replacement items in order to control costs.

Compared with the alternatives of having the original gearbox remanufactured, or indeed building new ones, the cost of the Brevini engineered solution is at least half that of estimates made for the alternatives.

Meeting strict cost criteria has become an increasingly important facet of most public service and utility engineering projects, making the Brevini solution ideal because it uses up-to-date technology that can be applied with a cost saving.

The savings are not just limited to the purchase and installation cost. Brevini planetary gear reduction stages are 98% efficient and a five-stage reduction can be powered by a small electric motor. Using less power, the package delivers an overall efficiency of 87.5%. This high level of energy efficiency will provide substantial energy savings when compared with the original units.

Snaith adds: “Brevini UK is expanding its solutions within the utility sector and offers a series of planetary reduction stage gearbox designs that are ideal for use in arduous applications in the water industry such as scrapers, aerators and pumping installations.

“The company has a long-standing history of supplying OEMs of new water treatment equipment worldwide because the majority of applications lend themselves to the low-speed, high-torque characteristics that make planetary solutions ideal. More recently, Brevini has been supporting more UK water companies with ‘engineered solutions’ to troublesome obsolete gearbox drives.”

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