Failed Belt Problem Case at a Product Mixer
A step increase in velocity was detected during routine monitoring of a product mixer. A new peak at 375 rpm, around 0.6 x running speed, was identified as a belt frequency due to a failed belt.
We noticed a step increase in overall velocity during routine condition monitoring of a product mixer. Upon inspection of the velocity spectrum, a new peak was present at 375 rpm, around 0.6 x running speed.
Being sub-synchronous we suspected a belt frequency and decided to visually inspect and get belt and pulley measurements. During the inspection, we found that one of the eight belts had failed and was sat inside the guard.
Calculations confirmed that the belt frequency was the new dominant peak. Our client was informed and a plan was put in place to replace the belts during a planned stop.
Belt frequency = π x pulley rpm x (pulley diameter / belt length)
= π x 658 rpm x (770 mm / 4250 mm)
= 374 rpm
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