NTNUKFS309D1Four-Bolt Square Flange Mounted Ball Bearing Unit, Cast Iron, 45 mm Tapered-Bore Insert for 40 mm Shaft, Adapter Sleeve Mount

Product Description

What this part is

An NTN UKFS309D1 mounted ball bearing unit: a cast iron four-bolt square flange housing carrying a UK309 wide inner ring insert with a 1:12 tapered bore. The insert’s spherical outer surface seats in the housing’s matching spherical bore, so the bearing self-aligns to shaft-to-housing angular error as the unit is bolted down. The unit bolts to a machine face perpendicular to the shaft, with the shaft passing through the flange.

Housing style and bolt pattern

Four-bolt square flange, cast iron, in NTN’s heavy-section FS housing series. The four bolt holes sit at the corners of a square, so the unit resists moment load in every direction and is the usual choice where a shaft passes through a bulkhead or gearbox face. NTN’s other flange styles are separate parts on the same insert: FL is the two-bolt oval flange, FC is the piloted cartridge flange with a register spigot, and the pillow block styles bolt to a base parallel to the shaft.

Bore, shaft size and mounting hardware

The UK insert has a 1:12 tapered bore of 45 mm nominal, and it mounts on an adapter sleeve rather than directly on the shaft. The sleeve for a UK309 is an H2309X, and its shaft seat is 40 mm — one bore-code step below the insert bore. So the tapered bore figure is 45 mm and the shaft the unit fits is 40 mm. Adapter sleeve H2309X, with its locknut and lockwasher, is not included. Drive-up along the sleeve taper both clamps the insert to the shaft and sets its internal clearance, which is why the adapter type grips a plain shaft harder than a setscrew insert and holds concentricity better.

What these specs mean in practice

An adapter sleeve mount is the choice for reversing duty, heavy shock and higher speed, because the clamp is a full 360° interference rather than two point loads from setscrews. It also allows the unit to be positioned anywhere along a plain shaft with no machined step, keyway or flat. The trade is assembly time and the extra part: setting the drive-up correctly is a measured operation rather than tightening two screws.

Quantity and configuration

1 Pc. Cast iron four-bolt square flange housing with its UK309 tapered-bore insert and seals. Supplied without adapter sleeve H2309X, without locknut and without lockwasher.

Fitting notes

The sleeve goes onto the plain shaft first, the insert is driven up the taper to its set position and locked, and the housing is then bolted to a flat rigid face, shimmed where the face is uneven. The bolts are brought up evenly so the spherical seat can find its alignment before final torque. Relubrication is through the grease fitting in the housing.

Interchange guidance

The interchange is another maker’s four-bolt square flange unit taking a UK309-pattern adapter-sleeve insert on a 40 mm shaft: NSK UKFS309 or the equivalent Asahi, FYH and SNR adapter-sleeve flange units at matching flange bolt centres. UCFS309 is a related size, not a substitution, because its insert has a straight 45 mm bore and setscrew locking, so it fits a 45 mm shaft directly. UKFL309 and UKF309 are the same insert in two-bolt oval and standard square flange housings, and UKP309 is the pillow block form — each a different housing.