MRO Magazine

Bearing isolator, shaft-grounding ring combo protect bearings


January 18, 2011
By PEM Magazine

The new Garlock SGi shaft grounding bearing isolator is the first seal to protect bearings from electrical damage as well as from lubricant loss and contamination.

Maintenance-free, the Garlock SGi combines the proven technologies of the Garlock GUARDIAN non-sparking bronze labyrinth seal and the AEGIS shaft grounding ring in a single unit. It is suited for motors controlled by variable frequency drives (VFDs) running pumps, fans, high-speed spindles, and other equipment in “severe-duty” applications such as mining and the processing of pulp/paper, food, pharmaceuticals, chemicals, and water/wastewater.

Commonly used to save energy, VFDs induce motor-shaft currents that can damage bearings, completely wiping out any energy cost savings.  Standard bearing seals only keep out contamination and prevent leaks, but the Garlock SGi diverts harmful currents safely to ground, bypassing the bearings entirely and extending motor life. The patented AEGIS FiberLock channel built into the Garlock SGi permanently secures circumferential rows of conductive microfibers, preventing their dislocation and the resulting accidental contamination of the bearing. The microfibers themselves, proven in hundreds of thousands of installations to protect bearings from harmful currents, are specially engineered for exceptional flexibility to prevent breakage and ensure that the SGi will last for the service life of the motor.

Designed for long-term total bearing protection, the SGi also provides an IP56 non-contact isolation seal that withstands dust and powerful jetting liquids.  It easily replaces contact lip seals and traditional bearing isolators used in nearly every industrial application and withstands operating temperatures from –22°F to 300°F. The unit is available for motor-shaft sizes ranging from 0.875 to six inches in flanged, flangeless, and custom configurations.


“No other seal provides the SGi’s level of protection against costly maintenance,” says Earl Rogalski, senior product manager for Garlock Sealing Technologies. “With it, we now offer our customers more reliable bearing protection than ever before.”