KEW Foundries’ extensive iron casting experience and quick turnaround secured the company a contract with winding systems expert Coilmech in October last year to supply sheave wheels for a new Sasol coal shaft project. Similar to the arrangements provided for two previous developments in Sasol’s iThemba Lethu and Irenedale Shafts, this project had some specific design requirements and saw KEW Foundries working in collaboration with Coilmech and third-party engineers, all the while upholding the foundry’s strict manufacturing standards.
This project required the delivery of two sets of cluster sheave wheel arrangements, one for the counterweight design and the other for the cage design. The cluster sheaves would be used in the doubling down condition and would be fitted into the conveyances. Each design consisted of six sheave wheels mounted onto a single rotating shaft and fitted with spherical roller bearings, which are in turn placed into specially designed heavy duty bearing housings. One sheave wheel is fixed to the shaft by means of a locking assembly; the other five float on phosphor bronze bushes.
Besides fitting into a confined space and varying rope centres between the two sets, the main requirement of the design was to meet a safe working load of 120 000kg and a rope-breaking load of 635 000kg over six ropes.
The tight restrictions on rope and steelwork support centres necessitated the design of new sheave wheels with different rope centres for each set.
In total, KEW Foundries made the 1.96m tread diameter sheave wheels from solid Grey cast iron, a design-friendly material that can be moulded into any form needed and is a more cost-effective alternative to steel. Completely assembled with spindle and bearings, the cluster sets each weigh in at 11 000kg and the foundry is not only arranging transport, but also manufacturing separate cradles to protect the bearings from damage and shock during the move.
With this project, KEW Foundries has continued its successful ten-year relationship with Coilmech.
KEW Foundries was established in 1891 and is Africa’s sole manufacturer of cast headgear sheave wheels. The company also offers an extensive range of hand-moulded castings in Grey and SG Iron up to 7t in weight, pressings and Cameron compressed air sludge pumps. Supported by comprehensive design and drafting facilities, including a dedicated pattern shop, machine shop and laboratory, KEW Foundries serves a host of South African and international mining and industrial markets.