Planetary gearboxes drop in to upgrade efficiency

Edited by the Engineeringtalk editorial team Sep 9, 2005

Thames Water has replaced old Varatio Strateline gearboxes with new Brevini multistage planetary gearboxes on a series of half-bridge scrapers at Maidenhead Sewage Treatment Works.

Thames Water has replaced old Varatio Strateline gearboxes with new Brevini multistage planetary gearboxes on a series of half-bridge scrapers at Maidenhead Sewage Treatment Works (STW).

The new Brevini planetary units offered increased radial load and torque transmission ratings over their predecessors and were easily retrofitted to the existing platform.

The cost of a direct replacement from Brevini significantly undercut the cost of refurbishing the originals or fabricating new bridgework to accommodate another manufacturers design of gearbox.

The Strateline units had reached the end of their service life at Maidenhead STW and when one completely failed (there is built-in redundancy at the site so the breakdown did not affect overall performance at the plant), the 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 an existing framework agreement for the supply of new 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 on old archive data on the Varatio Strateline gearbox and what it was capable of transmitting.

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

The new Brevini planetary gearbox has increased ratings over its predecessor on radial load and torque transmission.

This ensures that the planetary gearbox should be a permanent solution for many years to come.

The solution means that the original mounting and bridgework, which is sound, can be retained and the new gearbox fitted without any alterations being made.

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 which would have involved replacing all worn parts with new parts made from scratch, or dismantling the scraper drive and bridge and adapting them to accommodate a new gearbox or indeed building new ones, the cost of the Brevini engineered solution is at most 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 are expanding their solutions within the utility sector and offer 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 OEM manufacturers 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 have been supporting more UK water authorities with 'engineered solutions' to troublesome obsolete gearbox drives".

Brevini gearboxes are available off the shelf and with engineering support via any one of BSL Brammer branches nationwide.