A Fast Response to a Slow Drive Obsolescence Issue

Slowly crawling around the waste tank walls, half-bridge wall drives scrape the bottom of the tank to agitate and aerate the liquid – encouraging the aerobic activity which leads to breakdown of the waste.

The exceptionally slow speed means that any build-up of waste against the scraper happens at an equally slow rate, allowing the scraper to continue in operation for a long period of time in spite of it. However, if the build-up is not spotted and removed in time, ultimately it leads to a catastrophic failure.

Despite this potential for failure, one utility company’s wall drives – manufactured by a now long-defunct engineering company and incorporating Brauer wheels and double-reduction drive units – had been in operation for over thirty years.

But now they were beginning to show signs of age. These included significant wear within the castings, and a loss of tolerance in the bearings.

At the same time, the cost of new worm and wheel sets was becoming unsupportable, especially when the amount of plant downtime to install replacements was taken into account.

At the same time, the cost of new worm and wheel sets was becoming unsupportable, especially when the amount of plant downtime to install replacements was taken into account.

Stand by for a shock

One of the major reliability improvements ERIKS’ engineers were looking for was in avoiding the risk of catastrophic failure.

The Fenner CYCLO is the ideal solution, thanks to its exceptionally high shock capacity. Whereas most units have a shock capacity of just 200%, the Fenner CYCLO has a shockload rating of up to 500% of torque rating.

This high rating, combined with the slow speed at which the debris and therefore the load build up, gives more time for one of two things to happen. Either the debris will clear itself naturally over time, which then restores the normal load, or the unit will have plenty of time to alert the control panel so it can be turned off and the debris manually removed – long before the load is sufficient to cause catastrophic failure.

Putting it all together

This particular utility company has over 200 half-bridge wall drives in operation, all of which are coming to the end of the useful service life. To help them prepare for the inevitable need to replace their existing units – whilst maintaining continuity of operations – ERIKS have now created a modular solution.

This comprises a standalone shaft housing assembly with parallel and taper shaft options – engineered by ERIKS – a bearing housing, a plug-in Fenner CYCLO gearbox with a wide range of output speeds and an IEC frame dry fit motor. The assembly features adjustable feet to allow for different base-to-centre heights, and the bearing housing can be used as a slave unit to accompany the drive unit.

With these modular components kept in stock, when an in-service unit fails it takes only 2-3 days to assemble a complete drive operating to the customer’s specified ratio, and to deliver it ready for installation. 

Other utility companies can take advantage of ERIKS’ experience in the industry with an obsolescence survey. This enables ERIKS to see critical plant in operation, to understand the issues and commonalities across sites, and to devise a service exchange programme to maintain reliable operation.

And even if the utility companies’ process is a slow one, ERIKS’ service won’t be.