Timken Fafnir Mounted Ball Bearings Pillow Blocks and Flanges

Wide inner ring mounted ball bearings in pillow block, flange and take-up housings

Timken Fafnir mounted ball bearings are ball bearing inserts with a wide inner ring that is clamped to the shaft, pressed into a cast-iron or polymer housing and aligned through a spherical outside diameter. The Fafnir name has been associated with the wide inner ring design since the early 1900s, and Timken builds the range today in four duty classes, six housing shapes and three shaft-locking methods. They are the typical choice for conveyors, fans, pumps and packaging lines where a split plummer block would be oversized.

Timken lists the features of the current block as a grease fitting offset to reduce impact damage, grade 10 balls for quieter running, Buna-N seals with cotton fibre that wicks oil, a 6/6 nylon heat-stabilised retainer with good misalignment capability, a black powder-coated epoxy finish, double-filtered polyurea grease, solid flat feet and a block that is wider along the shaft axis and 30 percent heavier than the earlier design.

Technical specifications

Duty classes printed in the brochure:

How to read the code and choose the locking style

A Fafnir unit code combines the series letter and the housing: R, V, S, Y, T or L for the series, then AK (low base pillow block), AS (high base), CJ (four-bolt flange), CJT (two-bolt flange), TB (tapped base) or TU (take-up). Heavy-series housings use AO and cylindrical cartridges use C. In the insert code a G prefix means relubricatable, 1 is the 200-series, L is the light series and N the heavy 300-series, K is a full-width inner ring and RR means two land-riding rubber seals. The last three digits give the bore: the first digit in inches and the last two in sixteenths, so 103 is 1 3/16 inch.

Use an eccentric collar where the shaft turns in one direction and the collar can self-tighten, a set screw or Shaft Guard where the direction reverses. Timken suggests grease GR220 for Fafnir ball units (except the Survivor Series) and GR231 food-safe grease for the PT, NT and PS Survivor units.

What to confirm before ordering

Confirm the shaft diameter in inches or millimetres, duty class, housing shape and base height, locking style, seal type, whether the unit must be relubricatable or food grade, and the direction of rotation. A mixed insert and housing is possible if the stocked unit does not match. Related items sit under Electric Motors, Pumps and Turbines.

Selecting a Fafnir unit step by step

Choosing a mounted ball bearing is easier when the decisions are taken in a fixed order. Begin with the shaft: its diameter and whether it is inch or metric decide which insert bores are possible. Next, consider the load and speed of the application to settle the duty class, remembering that the medium-duty Y series offers more capacity than the standard series for the same bore. Then pick the housing shape that matches the machine frame, whether a low or high base pillow block, a flange, a tapped base or a take-up unit for belt or chain tensioning.

• Choose the locking style from the direction of rotation: eccentric collar for one direction, set screw or Shaft Guard for reversing drives.
• Decide whether the unit should be relubricatable, and whether food-grade lubrication is required.
• Consider the Survivor Series polymer or nickel-plated housings where washdown or corrosive conditions apply.
• Use the nomenclature to build the full unit code before requesting prices.

Mounting and start-up guidance

Mount the housing on a flat, rigid surface and align the units on a common shaft before final tightening, using the spherical outside diameter of the insert to take up small initial misalignment rather than relying on it to correct a poorly prepared frame. Lock the insert to the shaft only after the housing bolts are tightened, and follow the brochure for the locking method used. Check that the shaft turns freely by hand before connecting the drive.

After start-up, listen for unusual noise and check the housing temperature during the first hours of operation, since a gradual rise followed by stabilisation is normal while the grease distributes. Recheck bolt and locking tightness after the initial run-in period.

Operating mounted bearings in GCC conditions

Conveyors, fans and pumps in Oman and the Gulf often run in sand-laden air, high summer temperatures and coastal humidity. Relubricatable G-prefix units allow fresh grease to purge contaminants, so set a relubrication interval that reflects dust and temperature at the site rather than a generic schedule, and use the grease Timken recommends for the unit type. Keep housings clean so heat can escape, and inspect units on exposed equipment more often during sandstorm seasons. In food and washdown areas, the Survivor Series and the food-grade grease option should be considered from the start.

What to include in your RFQ

Provide the complete unit code if known, or the shaft diameter, housing type, duty class, locking style, lubrication requirement, application and quantity. For replacements, a photo of the existing housing and insert markings helps confirm the correct match.

Documents and quotation

The attached Timken brochure lists the series features, the housing and insert combinations and the nomenclature. Send the complete unit code and quantity when requesting a quotation from Seven Star LLC, an independent supplier in Muscat.