Despite Isaac Babbitt's invention of a revolutionary metal bearing alloy in 1839, wood remained popular, and continues to this day to be the most "shaft-kindly" bearing material available. Even the latest engineering plastics fail to protect metal shafts as well as wood. There are innumerable historic examples of wood bearing use, only a few of which we've mentioned here. Do you have one we've Missed?
While Woodex still builds the occasional lignum vitae bearing for water-immersed applications, this extremely dense (it won't float), slow-growing hardwood has been lumbered off. Though not extinct, the trees take three to four hundred years to mature, and only small cross sections of the wood are available. For those curious about lignum vitae, Woodex uses a species called, Guaiacum Coulteri. This wood has a beautiful blue Flower.
Since 1904, Woodex has produced a bearing material from rock maple, impregnated with petrolatum wax. This highly-durable substitute for lignum vitae is used extensively in wet and dry screw and roll conveying machinery, frequently in agricultural service. When the inevitable sand or grit invades the journal interface, a wood bearing compresses, absorbing the pollutant into its surface, and covering it with a film of oil: the very substance which typically destroys shafts becomes a benign part of the bearing! The wood releases lubricant when the shaft begins to spin and the journal interface heats; when the shaft stops and the journal cools, the natural capillary action of the wood retrieves the lubricant. Woodex bearings are thus permanently lubricated. Woodex manufactures direct replacement parts for Arguto® and Pobco® oil-impregnated wood bearings.
Woodex bearings are available in Conveying Equipment Manufacturing Association standard sizes from 1" through 3 7/16", and custom models are made for virtually any shaft diameter. Woodex manufactures the ONLY split screw conveyor hanger bearings with a true bore (they're split BEFORE they're bored). We invite inquiries on our 800 line, by email, or surface mail. The Woodex technology was purchased in 1968 from The Wakefield Corporation, which now specializes in the manufacture of sintered metal products.
Revised 20 December, 2002 Stark