Engineers at United Utilities’ water treatment plant at Widnes have replaced solid bearings with Revolvo SRB split roller bearings in an effort to save costs. These are easy to maintain, and avoid having to remove the long, horizontal agitator driving shafts. Previously, a crane with an 80ft reach was required to completely remove the solid support bearings, at a cost in excess of £2,500 per day.
In the past, these shafts have always been supported by two solid bearings with internal seals. But during periods of heavy rain, it is possible for the sludge level in aerator tanks to rise to the point where the bearing units become temporarily submerged, compromising the bearing seals and leading to premature bearing failure.
Changing the solid bearings, involved lifting each shaft clear of the tank and, depending on the level of corrosion, it may then have to be completely removed for workshop based remedial work. In either case, the most substantial part of the cost is crane hire.
Revolvo evaluated the existing application conditions, and proposed the split roller bearings replacement. The units were specified with housings and supports that could be interchanged with the existing bearing units wherever possible, or incorporate adapter plates, if necessary. The housings were equipped with high-performance, split rubber lip seals with garter springs and retaining plates, to guard against water ingress during intermittent submersion. As the SRB units are self-aligning, the seals are always concentric with the shaft, thus ensuring maximum seal efficiency.
Meanwhile, Revolvo has taken a step forward in the manufacture of very large bearings. The acquisition of new CNC and wire erosion machines, means the company can now manufacture standard and bespoke solid and split bearings in sizes up to 1.5m outside diameter, and at lead times of less than 36 weeks.