TimkenRAK2-15/16Two-Bolt Pillow Block Ball Bearing Unit, 2-15/16 in Bore, Eccentric Locking Collar, Cast Iron Housing, Non-Expansion

Product Description

What this part is

A two-bolt base pillow block ball bearing unit for a 2-15/16 in shaft, from Timken’s Fafnir-legacy RA insert range. The insert is a wide inner ring ball bearing with contact seals, secured to the shaft by an eccentric locking collar, mounted in a nickel-plated cast iron housing.

In Fafnir nomenclature RA denotes the wide-inner-ring insert and K denotes a pillow block housing. Fafnir’s four-bolt flange codes are RCJ, RCJO and TCJ, and the two-bolt flange is RCJT. Timken catalogues RAK 2-15/16 under eccentric locking collar units.

Why an eccentric collar rather than setscrews

An eccentric collar locks by interference rather than by biting into the shaft. The collar has an eccentric counterbore that matches an eccentric register on the insert’s extended inner ring, and a quarter turn in the direction of shaft rotation cams the two eccentrics against each other to grip the shaft. A single setscrew in the collar holds it in position.

The result is no dimples punched into the shaft, so the shaft survives repeated bearing changes and remains reusable; a concentric grip that does not push the inner ring off-centre the way an unevenly tightened setscrew pair can; and reliable holding under load reversal. The collar grips only when turned in the direction of shaft rotation, so the arrangement is direction-dependent.

Published data

Bore: 2-15/16 in. Housing style: two-bolt base pillow block, cast iron, nickel plated. Locking: eccentric locking collar. Seals: contact seal. Expansion: non-expansion (fixed). Base to bore centreline: 3-5/16 in. Bolt centre to centre: 9-1/2 in. Overall L x W x H: 10-1/2 x 3-5/8 x 6-7/16 in. Dynamic load rating: 14,000 lb. Static load rating: 10,100 lb. Weight: 19.9 lb / 9.026 kg. Maximum temperature: 250 °F.

Mounting data

This is a non-expansion unit, so it locates the shaft axially. On a shaft carried by two or more bearings, only one is non-expansion and the others float, so that thermal growth does not load the bearings against each other.

Self-aligning inserts of this type tolerate a degree of initial misalignment between the two bearing seats, which is why pillow blocks dominate conveyor, fan and line-shaft work. That tolerance covers static mounting error rather than a permanently misaligned running shaft.

Interchange guidance

Cross-references: RAK2-15/16, RAK 2-15/16, RAK2 15/16, RAK-2-15/16, RAK2-15-16, Fafnir RAK2-15/16. Related Fafnir housing styles taking the same insert size: RCJ (four-bolt flange), RCJO, TCJ, RCJT (two-bolt flange), RCJC (cartridge). Obsolescence trail: Fafnir was acquired by Timken, so Fafnir RAK numbers are quoted and supplied by Timken.