Craft Bearing: On Solid Ground With Split Bearing Solution

Craft used its standard split roller bearing (the same bearing that is popular for use on marine drive shafts, rudder shafts and lifting equipment) to transform a couple of standard 2.5-in. schedule 80 pipes into precision drive shafts for critical positioning equipment in the United States Navy Research Laboratory's new Spacecraft Rendezvous and Docking Simulator. Craft's engineers designed this large, state-of-the-art equipment to maneuver full-sized spacecraft to simulate the terminal docking phase during rendezvous in space. They needed a long, rigid, lightweight drive shaft for the precision control of the docking spacecraft. Craft's engineers developed an effective and inexpensive solution that could be applicable to almost any situation where line shafts are needed.

Craft's engineers simply made the drive shaft from standard pipe rather than solid machined steel. This was possible because the use of a Craft Split Bearing required machining only the area where the bearing was to be installed. The rough 2.8 in. outside diameter of the pipe was easily turned to 2.7 for about six-in. near the center of the 20-ft. pipe sections. Each end was bored to 2.3 inside diameter to accept Trantorque keyless bushings.

The pipe sections were installed on either side of the girder mounted, lowbacklash, parallel shaft gear reducer.

Short stub shafts at each end were fitted with drive sprockets. The standard Craft SI-212 BCH Split Roller Bearing was then installed around the shaft.

Due to the high lateral stiffness and lightweight of the pipe sections, only one Craft Bearing was required at the mid-span of each pipe drive shaft. When engineers compared the pipe drive shaft with a conventional 2-in. solid drive shaft, they found that the pipe shaft was: 28 percent lighter; 70 percent stronger; and 140 percent more rigid.

The ability of the Craft Split Roller Bearing to be assembled around the shaft saved hours of machining, reduced installation time, and made the concept feasible. This innovative approach should be considered by anyone using line shafts that need intermediate support.

This is particularly true in the marine industry where strength and weight are such important considerations.

Craft split bearings are designed to be easy to install because they eliminate the need to remove shafts and drive components.

In addition, to increased reliability and longevity, the Craft bearing has a host of other innovative features.

• Strong ductile iron casting, also available in stainless steel • Split triple labyrinth seals eliminate shaft wear and extend seal life; • Patented split integral locking roller cage with cylindrical pockets for positive roller alignment and retention; • Standard base-to-center height; • Approved by Lloyd's Register; • Powder coated for a durable finish; • Metric, large bore, special applications, unique sizes, special bore diameter, modified base to center heights and custom bearings are also available.

• Complete technical support. Craft's engineers in Hampton, Va. are eager to help with solutions for special problems and application questions.

• Rapid response to all orders. Same day shipping at no extra cost on all bearings in stock, including large bore bearings.

Circle 62 on Reader Service Card

Maritime Reporter Magazine, page 28, Mar 2001

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