I have experienced a similar problem, induced by the tail take-up pulley. The resonance however occurred at the support structural bent.

At our first commercial sandwich belt high angle conveyor installation the truss structure was supported at the head end by a structural bent, 25 meters high, made of wide flange beam columns with bracing between. The high angle conveyor's belt speed was about 5 meters per second. During running the bent columns would periodically vibrate violently, laterally along their strong axis. It was not initially clear what was the cause. After recording the resonant frequency at the bents we looked for possible excitation frequencies. The rotational frequency of the tail pulleys was amazingly close the the resonant frequency of the bent columns. We added structural tee's to the columns, to increase their depth, stiffness and natural frequency. This solved the problem by taking them out of the range of the excitation frequency.

Joe Dos Santos ■

Originally Posted by Author

Resonance in Tail Drums on Bulk Conveyors



Greetings,

I work in a large grain export silo in south-western Australia which has recently undergone an upgrade of its capacity. Since the upgrade we have noticed that certain conveyor belts have sporadic squealing (resonating) sounds coming from the tail pulleys and bend pulleys. I have checked all the obvious areas i.e. bearings, alignment etc. when the problem drums are making noise I have found that if I apply a belt grip style product directly to the drum it instantly stops the noise, for a very short time at least. The head drums are lagged and the other drums are fitted with under speed sensors so slippage is not the problem.

I was wondering if you have ever came across this problem.

Best regards

Ryan Innes

Australia

Dear Mr.Ryan Innes,

In addition to the advice of Mr.Joseph A. Dos Santos, requesting to reply for the following queries also:

Are all the pulleys fixed with speed sensors ? What is the accuracy of these speed sensors ? How are the lagging on the pulleys? Are they slightly worn out ? How is the shaft fixed with the pulley ? Are they hub and keyed with the shaft ? Are they tightly fixed ? Hoping to get the answers at the earliest? From your line of "belt grip style product directly to the drum it instantly stops the noise, for a very short time", I think there could be a very minor gap between the belt and the pulley at few area.

I have heard such noise in our conveyors also. It was like a continuous whistling ( Squeaking ) noise.

Regards, ■