Mainstream Engineering Consultants (MEL) were engaged to supply a new girth gear for a customer’s drum debarker that was unable to be economically sourced from New Zealand within a short time frame. The girth gear required replacing as after many years of service it was severely worn, reaching the point where teeth were starting to break off and threatening production continuity.
The girth gear dimensions were 4,850 OD x 485 mm wide and was supplied in 2 halves with a total weight of 8,000 kg. The ½ joints were machined and drilled for bolting together around the existing drum with fitted bolts. The customer specified the gear material was to be grey cast iron (grade 250). All machined dimensions were to a tolerance of +/-1mm excluding the gear tooth machining which was specified as AGMA(USA) Quality no 4.
MEL completed the design review and fabrication detail, then with key suppliers sourced and supplied the gear from a foundry in China with the capability for this sized casting and ability to deliver within the required timeframe. SGS New Zealand were engaged to facilitate the inspection programme to ensure material properties and machining tolerances were complied with.
The combination of MEL’s technical expertise, practical engineering experience and partnerships with key suppliers ensured a high-quality gear was delivered within a short time frame to the customer’s store in time for fitting by the customer during a planned major outage. The gear has provided trouble free operation since installation.