Mounted Bearing & Pillow Block Interchange Guide

How a mounted bearing unit is built

A "mounted bearing" or "pillow block" is a cast iron, cast steel, or thermoplastic housing holding a spherical-OD insert bearing (also called a Y-bearing) that self-aligns inside it. The housing determines how the unit bolts to a machine frame; the insert determines the shaft bore and does the actual load-carrying. Because the insert's bore and spherical outside diameter are built to a shared industry convention, most brands' inserts fit the equivalent housing size from another brand — but the two parts of the part number (housing style + insert bore code) need to be read separately.

Reading the bore code (the reliable part)

For inch-bore mounted units, the number at the end of the part number is the bore expressed in sixteenths of an inch — divide it by 16 to get the bore diameter. This holds across brands: a part ending in -16 is a 1.000″ bore (16 ÷ 16), -20 is 1.250″ (20 ÷ 16), -24 is 1.500″ (24 ÷ 16), and -28 is 1.750″ (28 ÷ 16). You can check this against any inch-bore mounted bearing we list: the bore called out in the description always resolves to that suffix divided by 16. Metric-bore units use their own standard bore-series code instead of the inch suffix — the exact bore in mm for a metric part is always stated directly in its listing, so confirm it there rather than assuming a conversion.

Housing style prefixes

The letters before the bore code describe the housing, and the same short-hand is used industry-wide, though individual manufacturers add their own extra letters for material, coating, or lubrication options:

Locking style — the detail that is not interchangeable

The insert locks onto the shaft one of two ways: a set screw (usually two, offset 120°) or an eccentric/concentric locking collar. These are not interchangeable with each other at the same bore — a housing bored for a set-screw insert will not correctly seat a locking-collar insert, and vice versa. Every mounted bearing we list states its locking style directly in the description; match it along with the bore and housing style.

This guide covers the widely-used bore-suffix and housing-prefix conventions used by SKF, FYH, IPTCI, Sealmaster, and similar mounted-unit lines. Specialty and spherical-roller replacement insert kits from some manufacturers use their own model-specific numbering outside this convention — always confirm bore, housing footprint (bolt-hole spacing), and locking style against the exact listing or datasheet before ordering a substitute for a critical application.

Finding the equivalent for a part you already have

Take the bore code and housing letters off the part you have, convert the bore using the rule above, and search that bore/housing combination in our catalog — or search the exact part number if you already have it.

Live examples from our catalog

Currently listed mounted bearings, pillow blocks, flange units, and inserts across the brands we carry — open one to see its full spec sheet.

• P2B 208-SRB-SRE — SKF — P2B 208-SRB-SRE Pillow block roller bearing unit, inch series
• PFT 47 — SKF — PFT 47 Oval flanged pressed steel housing for insert bearings
• P2B 015-TF-AH — SKF — P2B 015-TF-AH Pillow block ball bearing unit with extended inner ring and set screw locking, cast iron, North American standards
• SDAF 244 — SKF — SDAF 244 Split plummer (pillow) block housing without included bearing
• SAF 511 — SKF — SAF 511 Split plummer (pillow) block housing without bearing
• 22220LBC0 — Link-Belt — Link-Belt 22220LBC0 Bearing Inserts (Unmounted Replacements)
• SYNT 35 LTS — SKF — SYNT 35 LTS Pillow block roller bearing unit, metric series
• F2B 25M-TF — SKF — F2B 25M-TF Oval flanged ball bearing unit with set screw locking, cast iron housing, North American standards

Frequently asked questions

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