When wet concrete is poured, air voids can occur which, after it dries, can ruin the aesthetic look of exposed surfaces and also reduce the structural integrity. Concrete poker vibrators are used to dispel these bubbles. For this, the heavy end of a poker vibrator is dropped deep into the wet concrete attached to a thick cable which terminates at a power source, creating a high frequency vibrator unit. This, however, puts huge stress on the rotating bearings in the system.

So, during the development of a new type of electric poker for its concrete head vibrators, one manufacturer specified a deep groove ball bearing. However, the bearing needed to last over 1000 hours.

SO, NSK recommended replacing the oil used in the application and then suggested the type of bearing used in the design should be retained, but that it should be supplied with a larger radial internal Clearance (C4) to allow greater lubrication and allow for increased vibration damping within the bearing unit itself.

These modifications were made to a series of four bearings. Under test, all the bearings exceeded the previously unattainable 1000 operating hours and are now being specified for production.

NSK        www.nskeurope.com

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