SKFSYH1 3/4 FMTwo-Bolt Cast Iron Pillow Block Bearing Unit, 1-3/4 in Shaft, Eccentric Locking Collar, Contact Seals

Product Description

What this part is

An SKF SYH1-3/4-FM mounted ball bearing unit: a two-bolt cast iron pillow block housing with a pre-lubricated, contact-sealed insert bearing for a 1-3/4 in shaft. The housing bore is sphered and mates with the sphered outer diameter of the insert, so the bearing swivels in its seat to take up initial misalignment between the shaft and the mounting face.

Decoding the designation

SY — SKF Y-bearing (insert bearing) mounted unit
H — pillow block, or plummer block, housing in the inch series
1-3/4 — nominal shaft size in inches
FM — grey cast iron housing fitted with a YET-series insert, locked by an eccentric locking collar

Housing style and bolt pattern

Two-bolt pillow block. The bolt holes are slotted along the shaft axis, which lets the unit be shifted for belt or chain tensioning before the bolts are drawn down. Base and bore are on the same casting, so centre height is fixed by the housing size.

What these specs mean in practice

An eccentric locking collar grips by driving the collar against the offset counterbore of the extended inner ring, then setting a screw against the shaft. It resists rotation in the direction of shaft rotation better than a plain setscrew and needs no shaft shoulder, keyway or machining — a drawn or cold-rolled shaft is enough. The trade-off against a concentric collar or an adapter sleeve is concentricity: an eccentric collar leaves a small amount of runout, which is why these units suit conveyors, fans and general line shafting rather than precision spindles.

Contact seals on both faces hold grease in and keep dust and washdown out, at the cost of a little more running friction and a lower speed ceiling than a shielded insert.

Published specifications

Shaft size: 1-3/4 in (44.45 mm)
Housing style: two-bolt pillow block, inch series
Housing material: grey cast iron
Insert bearing: SKF YET 209-112, single-row deep groove ball
Locking method: eccentric locking collar
Seals: contact seals, both faces
Alignment: self-aligning, sphered housing seat
Relubrication: grease fitting in the housing
Expansion: non-expansion

Quantity and configuration

1 Pc. Complete unit: housing, insert bearing and locking collar assembled together.

Fitting notes

The unit seats on a flat rigid face, shimmed where the surface is uneven, with the bolts left loose until the shaft is through both bearings so the sphered seats can find their own alignment. The collar is then driven in the direction of shaft rotation and the collar setscrew tightened.

Interchange guidance

Dimensionally equivalent inch-series two-bolt pillow blocks with an eccentric collar include the Dodge P2B-SXVB-112. The insert alone is the SKF YET 209-112. A unit of the same bore with a setscrew insert (SKF YAR series) or a concentric collar is a related size rather than an interchange, because the locking method and the inner-ring geometry differ.