Thursday 21 July 2016

MOUNTING PULLYS AND COUPLING

A couling half or pulley that is a push fit on the shaft can be pushed on by hand for about half the length of the shaft extension. A special tool or a fully threaded bolt, a nut and two flat pieces of metal are used to push it fully home against the shoulder of the shaft.

 
If there is no tapped hole in the end of the shaft, the coupling half  can be heated to 80° C and pushed on to the shaft. If the coupling half is machined for a tighter fit than and the push fit, it mush be heated to abaouth 150 ° C. the coupling halp is locked with an end plate. To remove the coupling half, a puller is used.



It is bad practice to use a lead mallet when fitting pulleys or couplings, and especially bearings he harm that can be done by such treatment cannot be over emphasized. It causes pitting of the receways in the bearing, and this damage increases in service, leading to savere scaling. Statistics show that some 70 % of motor faults are ue to bearing defects, and many of these can be traced back to mistreatment during the mounting of a coupling or pulley.

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