Crossed-rollers strengthen largest naval radar bearing

The bearing of the rotating radar antenna atop the foremast of the Royal Navy's latest Daring Class destroyer must resist shock and overturn loads that would topple the unit and function reliably in a salt-spray environment.

Engineers at radar systems manufacturer Alenia Marconi Systems Ltd. selected a crossed-roller bearing designed in cooperation with The Timken Co. to support and turn the SAMPSON multi-function radar (shown below). At 3m in diameter, it is one-third larger than previous bearings of this type manufactured by Timken, says Tom Baker, chief engineer for process industries at Timken.

The crossed-roller configuration is essentially two sets of rollers in a common race. The rollers alternate with their axes at right angles to each other. This layout results in an overall bearing height that is marginally greater than that of a single bearing housing. But the load-carrying centers of each of the races (the point where the roller axes intersect the vertical axis through the center of the race) have a large "bearing spread," substantially taller than the physical depth of the bearing, which increases resistance to overturning moments.

Contact:Tom Baker, The Timken Co.Tel (330) 471-4392; e-mail: [email protected]http://rbi.ims.ca/3854-539

"Combs" keep cable carriers in line

Fixed guide troughs, which support cable carriers for long travel applications of automated machinery, can be an obstruction in factories where traffic is heavy. For those who don't want to obstruct forklifts and other factory traffic with a fixed steel tray, igus Inc. (East Providence, RI), has created a cable carrier that won't lose its alignment or derail, even on runs of more than 300 ft. As a result, the cable carrier needs no guide trough.

The cable carrier chain accomplishes that feat through the use of cross members that incorporate comb-like teeth and grooves. In long cable runs, when gravity pulls the upper portion of the chain onto the lower portion, the "combs and grooves" on the top portion mate with combs and grooves on the bottom. Upper and lower portions of the so-called "auto-glide" system therefore lock in place, keeping the cable carrier aligned. As a result, the new cable carriers need no metal trays or guide troughs, thus eliminating potential traffic obstructions in the factory.

Contact:Joe Ciringione, igus Inc.Tel (401) 438-2200 or (800) 521-2747 http://rbi.ims.ca/3854-540