Innovative engineering from SKF is playing an important role in improving the reliability of Pennsylvania rock crushers used by Aggregate Industries at its Torr Works quarry site near Shepton Mallet, Somerset.
Aggregate Industries, part of the Holcim Group, is a major UK quarrying business that makes continuous use of Pennsylvania rock crushers at its Torr Works quarry as part of the process of breaking up around six million tonnes of limestone every year. This material is then used in construction projects around the UK.
Each crusher incorporates a series of hammers mounted along a central rotor shaft to reduce the limestone to the required size. This process is particularly demanding on shaft bearings, seals and drive mechanisms, with considerable quantities of fine dust being generated. Due to the location of each crusher, limited air movement, and the design of the bearing housing, Aggregate Industries found that machine surfaces became heavily contaminated and that particles of dust were penetrating through the seals. This resulted in severe contamination of shaft and bearing lubricants, which in turn led to increased wear of moving parts, causing unplanned downtime and rising operating costs. The customer’s problems were exacerbated by the poor quality of the castings used in the original bearing housings, which were proven to be porous, allowing oil to leak from the arrangement.
Recognising that the solution required a complete refurbishment of the bearing housings and associated parts, Aggregate Industries turned to specialist mechanical engineers, Anstee & Ware. Anstee & Wear partnered with SKF and Antifriction Components, an SKF Authorised Distributor, to provide a custom-engineered system that enabled the replacement bearing housings and shaft assembly to be manufactured off-site to minimise downtime at the quarry.
SKF supplied new housings, each weighing 500kg and being fully tested to ensure that all risk of porosity was eliminated, plus replacement bearings and custom-sized adapter sleeves; the latter were required as the machining required to refurbish the rotor shaft had reduced the effective diameter. In addition, SKF designed a new arrangement of labyrinth and V-ring seals to provide a far higher level of shaft protection against the ingress of dust.
Andy Frankham, Sales Manager at Anstee & Ware, explains: “The refurbished system has now been installed on the Pennsylvania crusher and has been in continuous operation for some months without any problems. As a result, Aggregate Industries now has a custom-engineered solution that is delivering far greater reliability, efficiency and productivity than ever before. This could not have been achieved without the engineering support and technical knowledge provided by the SKF team in the UK.”
Aggregate Industries were so pleased with the solution that they have since placed another order to replace the bearing housings on the remaining Pennsylvania crusher.
To learn more about custom-engineered systems please visit www.skf.co.uk.