Plummer Block Bearing Housings

A standard pillow block (UCP200, UCP300) is a solid one-piece housing. The bearing must be removed by sliding it off the shaft end, which requires dismantling the drive at the shaft end and is impractical for large bore sizes or inaccessible shaft positions. A plummer block (SN500, SAF500) is a two-piece split housing with the split line at the shaft centreline. The top cap is unbolted and lifted off, the bearing insert is replaced, and the cap is rebolted — the shaft never moves. Plummer blocks are the standard for heavy industrial shaft support positions where shaft removal is impractical, typically from around 50 mm bore upwards and wherever fast bearing replacement without machine shutdown is required.

Plummer block housings are designed to accept spherical roller bearing inserts. For SN500, SNU500, and SNG500 (cylindrical bore housings), the bearing is either interference-fitted directly into the housing bore or mounted via an adapter sleeve that sits in the cylindrical housing bore. SYNT-series or equivalent spherical roller bearing inserts are the standard choice. For SAF500 (tapered bore housing), the housing bore is tapered to match the adapter sleeve OD, and the spherical roller bearing mounts on the adapter sleeve. Self-aligning ball bearings can also be used in the smaller bore sizes of SN500 housings.

Use SAF500 when the shaft is rough-turned or as-machined (not ground to a close tolerance), when the shaft will be reused between bearing replacements and shaft surface damage must be avoided, or when the bearing will be removed and reinstalled multiple times over the machine service life. SAF500 is designed for adapter sleeve or withdrawal sleeve mounted bearings: the sleeve distributes clamping load over its full contact length without marking the shaft, and the withdrawal sleeve allows the bearing to be removed by driving the sleeve off the shaft with a withdrawal nut rather than pulling the bearing itself. SN500 with direct interference fit requires a ground shaft to correct tolerance and the bearing must be pressed or driven on and off.

All three are cylindrical bore split plummer block housings accepting the same bearing inserts and mounting methods. The difference is housing body width. SN500 is the standard width, covering the widest bore range (25–340 mm) and the most common bearing widths. SNU500 has a wider housing body than SN500 at the same bore — used when the bearing insert is wider than SN500 can accommodate, such as wide spherical roller bearings or double-row inserts. SNG500 has a narrower housing body than SN500 at the same bore — used where the axial spacing between bearing positions is constrained and the shorter SNG500 body fits within the available shaft span. SNG500 is also lighter than SN500 at equivalent bore, reducing dead weight in overhead or elevated mounting structures.

Within the same series and size designation, plummer block housings follow standard dimensions that allow the top cap from one compliant manufacturer to be fitted with the base from another compliant manufacturer of the same designation. This interchangeability is valuable in the field when only one half of a housing is damaged and needs replacing. Always verify the split-line dimensions and bolt pattern before mixing caps and bases in service, as some manufacturers use proprietary dimensions for larger sizes outside the standard range.

Standard parts: quantity-based MOQ per model number. New-client samples: 1–5 pcs at sample price for first-time buyers. Multi-model orders: aggregate orders of USD 1,500 or more across models accepted. Retail (1–2 pcs): not accepted. Engineering drawings required before order confirmation — catalogue dimensions for reference only.