SealMasterMRP-24Two-Bolt Pillow Block Ball Bearing Unit, 1-1/2 in Bore, Setscrew Lock, Cast Iron, Relubricatable, Non-Expansion

Product Description

What this part is

A SealMaster mounted ball bearing unit for a 1-1/2 in shaft: a cast iron two-bolt pillow block. The insert is a self-aligning ball bearing with a spherical outer diameter and an extended (wide) inner ring, locked to the shaft by setscrews. The spherical seat lets the insert swivel in the housing to take up initial shaft misalignment at installation, so the housings bolt down to an imperfect frame and the bearings find the shaft.

Decoding the designation

SealMaster (now Regal Rexnord) codes the housing style in the prefix and the shaft size in the number. The number is sixteenths of an inch, so 24 = 24/16 = 1-1/2 in bore. NP-16 is a 1 in bore, NPL-23 is 1-7/16, NPL-39 is 2-7/16. In the prefix, a trailing P is the pillow-block family: MP medium duty, NP normal/standard duty, NPL low base, MPD/NPD double-lock, SP standard duty heavy housing. Flange units carry an F: SF and SFT are standard-duty four- and two-bolt flanges, MSF is the medium-duty four-bolt flange, MFC and SFC are flange cartridges. Take-ups are ST, MST and STU. There is no pillow block with an F and no flange with a bare P.

A flange block bolts through a vertical face or bulkhead with the shaft passing through it, while a pillow block bolts down onto a horizontal base beside the shaft. The published 1-1/2 in bore two-bolt pillow blocks in this family are MP-24 (medium duty), NP-24 (normal/standard duty, high base) and NPL-24 (low base).

What these specs mean in practice

Setscrew locking: two hardened setscrews at 120° clamp the extended inner ring to the shaft. It is simple, field-serviceable and tolerant of a commercial shaft tolerance, and it is less concentric than an eccentric collar or concentric-lock design.

Non-expansion: the insert is axially fixed in the housing. On a two-bearing shaft one bearing is the fixed unit and the other floats, so that thermal growth in the shaft does not load both bearings axially.

Relubricatable: SealMaster inserts carry a lubrication hole and dimple in the outer ring, so grease reaches the raceway through the housing fitting rather than only at assembly.

The cast iron housing with a self-aligning spherical seat is a general industrial machine element. For food or wet duty the stainless and coated equivalents are the CRPS and PN families.

Published mounting data

Bore / shaft size: 1-1/2 in (24/16 in). Housing style: two-bolt pillow block, base mount. Housing material: cast iron. Insert type: single-row self-aligning ball bearing, spherical OD, extended inner ring. Locking method: setscrew. Expansion type: non-expansion. Relubrication: through housing fitting.

Quantity and configuration

Price is per unit. Each unit ships as housing plus insert, complete, with setscrews fitted. Mounting bolts, shims and take-up frames are separate items.

Interchange guidance

SealMaster is now part of Regal Rexnord, so current literature and stock appear under that name; older paperwork will say SealMaster, Stephens-Adamson or Gold Line. Two-bolt pillow blocks for a 1-1/2 in shaft are a widely duplicated envelope: Dodge/Baldor P2B-SC-108 and P2B-SCM-108, Link-Belt P3U224, Browning VPS-224, Timken VPB-224, Sealmaster NP-24 and MP-24, NTN UCP-1.1/2 and SKF SYH 1.1/2 all serve the same shaft size. Base-to-bore centreline and bolt centres differ between series.