Machine Design

Pressure equalizer keeps gearboxes clean

Gearboxes in food processing and other plants exposed to frequent washdowns and dust

often use add-on pressureequalization systems to prevent sucking in water and contaminants during cool down. But most of them relied on bladders with multiple seams, all potential leak points. The systems were hard to install on gearboxes, and when they failed, it meant taking the gearbox down for maintenance. The Posivent system from Boston Gear, Hayward, Mass. (, uses a patent-pending pressurecompensation system that eliminates traditional breather vents. It is enclosed in a single-seam, sealed enclosure and is an option on all Boston Gear 700 Series gear reducers. The unit mounts in any position and can be installed at the last minute, fitting into any standard pipe plug and in any orientation. It has survived testing from 20 to 220°F, and at internal pressures up to 3 psi.

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