Rubber-in-compression Couplings Cure Mine's Bad Vibrations


Excessive vibration on plant and equipment at mines and quarries is a common problem that can damage machinery, cause premature failure and significantly increase maintenance costs.  It can result in damage to the machinery being driven as well as to the motor and the component parts of the power transmission system.  It can become a serious problem particularly if the vibratory frequencies approach the natural frequency of the equipment.

There are numerous options to address the problem but one of the easiest and most cost effective solutions is to fit rubber-in-compression type flexible couplings from Renold Hi-Tec. The benefit of rubber-in-compression couplings is that there is no metal-to-metal contact and the drive is through pre-compressed rubber elements that eliminate backlash, ensure that the natural frequency of the drive train does not coincide with the running speed and damp vibration.

Rubber-in-compression couplings are the ideal solution on the most arduous and heavy-duty applications across all mining and quarrying applications.  For example, Renold Hi-Tec successfully completed a project with a mining company in Australia to reduce a problem it was experiencing with extreme vibration in the drive train of one of the biggest grinding mills in the world.

The mining company operates a massive autogenous mill for grinding nickel ore that is powered by two seven megawatt electric motors that drive a 9.6 metre diameter shell with a huge girth ring 12.1 metres in diameter.  The mill grinds the nickel ore within a a rotating drum that propels material in a cascading motion causing impact breakage of larger rocks and compressive grinding of smaller particles.

Renold Hi-Tec's engineers analysed the levels of vibration and recommended the use of two PM600 rubber-in-compression couplings with specially selected rubber blocks.  The two couplings, located between two reduction gearboxes and the girth ring pinions, deliver 200KNm at a speed of 170rpm, completely resolved the problem with vibration.  The PM range of couplings is designed for applications up to 6,000KNm and the materials used in their construction make them particularly suited to applications where severe shock loads and vibration could cause major problems.