Pillow Block Bearing Sizes by Shaft Diameter

A pillow block is a mounted ball bearing in a cast iron base that bolts down beneath the shaft, and it is chosen by its bore first. The bore alone does not say whether a unit will drop into holes already drilled in a machine: that takes the height from the mounting surface to the shaft center, the distance between the mounting bolts, the overall length of the base and the bolt size. The tables below give those dimensions by shaft size for the standard-duty and medium-duty cast iron series from Sealmaster and Browning, followed by how to measure a block that is already installed, how a four-bolt base differs from a two-bolt one, and what separates medium duty from standard duty. All of these units are in the pillow blocks category.

What are the dimensions of a pillow block bearing?

Five dimensions decide whether a pillow block fits: the bore, which is the shaft diameter; the height from the base to the shaft center; the bolt spacing, between the centers of the two mounting holes; the overall length of the base; and the bolt size the mounting holes take. The bore selects the insert, and the other four decide whether the housing fits the frame and leaves the shaft where the machine expects it.

Bolt spacing is stated as a minimum and a maximum on every unit below because the mounting holes are slotted, which is what lets one block fit a spread of hole patterns. Base width, overall height and length through the bore complete the outline of a unit and matter where the block sits against a wall or a guard. Inch-series bores step in sixteenths, and the shaft size conversion chart converts a decimal or metric measurement to the fraction the tables use. The series in the tables run from a 1/2-inch bore to 4 inches. Metric bores carry a different number: on a Sealmaster block it is a 2 or 3 for the duty followed by the bore in millimeters divided by five, so NP-205 is the 25 mm standard-duty block and MP-305 the 25 mm medium-duty one.

What size pillow block fits a given shaft?

Find the shaft diameter in the first column of the series you are replacing, and the part number on that row is the unit. A 1-inch shaft takes a Sealmaster NP-16 or a Browning VPS-216, both 1-7/16 inches to center on a 5-1/2-inch base with 3/8-inch bolts; a 2-inch shaft takes an NP-32 or a VPS-232 at 2-1/2 inches to center. The Sealmaster and Browning standard-duty blocks share their height to center in every inch bore the NP and VPS 200 tables below both list except 1-1/2 inches, where the NP-24 sits at 1-15/16 and the VPS-224 at 2, but their bolt spacing and base length differ in most bores, so check all four dimensions before swapping one brand for the other on an existing frame.

All dimensions are in inches. Bolt spacing is the minimum and maximum the slotted holes accept. Part numbers link to the product page.

Sealmaster NP: two-bolt pillow block, high base, standard duty, setscrew lock

The NP is the standard-duty two-bolt block with a setscrew-locked insert. The number after the prefix is the bore in sixteenths of an inch, so NP-16 is a 1-inch bore and NP-32 a 2-inch bore.

Sealmaster MP: two-bolt pillow block, high base, medium duty, setscrew lock

The MP is the medium-duty two-bolt block. For the same shaft it sits higher, bolts further apart and takes a larger bolt than the NP, because it carries a heavier insert in a larger housing.

Browning VPS 200: two-bolt pillow block, high base, standard duty, setscrew lock

The VPS 200 series is Browning's standard-duty two-bolt block. The first digit after the prefix is the duty (2 for standard) and the last two are the bore in sixteenths of an inch, so VPS-216 is a 1-inch bore and VPS-232 a 2-inch bore.

Browning VPLS 200: two-bolt pillow block, low base, standard duty, setscrew lock

The VPLS 200 series is the low-base version of the VPS 200. In each bore it keeps the VPS bolt spacing and overall length and carries the shaft closer to the mounting surface.

Browning VPS 300: two-bolt pillow block, high base, medium duty, setscrew lock

The VPS 300 series is Browning's medium-duty two-bolt block; the 3 after the prefix is the duty digit. Like the Sealmaster MP against the NP, it is a larger housing for the same shaft.

How do you measure an existing pillow block?

Take four measurements with the unit still on the machine: the shaft diameter next to the block, the height from the mounting surface to the center of the shaft, the distance between the centers of the two mounting bolts, and the overall length of the base. Add the bolt diameter and the locking style, and those facts identify an equivalent from the tables even when the housing marking has worn away.

Check the housing first: a Sealmaster unit carries a metal nameplate riveted to the housing, and a legible part number on either brand decodes with the mounted bearing nomenclature guide. Otherwise measure the shaft and read its fraction from the conversion chart, then measure from the mounting surface to the top of the shaft and subtract half the shaft diameter to get the height to center. Compare the bolt center distance as fitted with the minimum-to-maximum range in the table: a replacement only has to cover the spacing in use, not the whole slot. When the height to center matches a row but the bolt spacing or base length does not, the unit is likely the other brand, the other duty or a low-base variant, and each of those has its own table above.

What is the difference between a 2-bolt and a 4-bolt pillow block?

A two-bolt pillow block has one slotted mounting hole at each end of the base; a four-bolt block has two holes at each end, side by side across a wider base. In the Sealmaster line the four-bolt base is a medium-duty housing, the MFP, offered from a 1-15/16-inch bore to 4 inches, while the standard-duty NP and NPL and the medium-duty MP are all two-bolt. In each bore the MFP sits at the same height to center as the MP, so the shaft height does not change between them; what changes is the base and the hole pattern.

On a 2-15/16-inch shaft the MFP-47 and the MP-47 are both 3-1/2 inches to center on a 13-inch base, but the four-bolt base is 5 inches wide against 3-1/2, its holes are spaced 9 to 10-1/2 inches along the base and 2-3/4 inches across it, and it takes 3/4-inch bolts where the two-bolt block takes 7/8. A four-bolt unit cannot replace a two-bolt one on the same holes, or the reverse, without re-drilling the frame.

What is the difference between standard duty and medium duty?

Standard duty and medium duty are two insert series in housings sized to suit them: a medium-duty block carries a heavier insert with a higher load rating in a larger housing for the same shaft. Sealmaster marks the duty in the insert number, 2 for standard and 3 for medium, and Browning in the first digit after the prefix, 2 for the 200 series and 3 for the 300 series. The housing prefix changes with it on the Sealmaster side, NP to MP, and stays the same on the Browning side, VPS 200 to VPS 300.

On a 1-inch shaft the standard-duty NP-16 and VPS-216 carry a basic dynamic rating of 2,801 lb; the medium-duty MP-16 and VPS-316 carry 4,381 lb. The housing grows with the rating: the MP-16 is 1-3/4 inches to center on a 6-1/4-inch base with 1/2-inch bolts, against 1-7/16 inches, 5-1/2 inches and 3/8-inch bolts on the NP-16. The standard-duty NP and VPS 200 cover bores from 1/2 inch to 2-15/16 inches, the Sealmaster MP from 15/16 inch to 4 inches and the Browning VPS 300 from 1 inch to 2-1/4 inches.

Which pillow block housings and bores do we stock?

We list 302 units numbered by a housing prefix and a bore alone, in the 14 housings below, every number a link to that unit. It is part of what we hold in the category, not all of it. Read the row for the base and the shaft lock the machine needs, then the number for the shaft: the prefix names the housing and the number after it names the bore. It reaches what the dimension tables do not — the low-base and collar-locked housings the sections above name without sizing, the tapped-base housings, whose mounting holes are threaded rather than slotted, and the metric bore numbers alongside the inch ones.

Every number here is a housing prefix and a bore and nothing else. Two sets of units sit alongside these in the pillow blocks category rather than in this table: a number carrying something further after the bore, which is the same housing in the same bore with an option added, and the further Sealmaster and Browning housings these tables do not describe — SP, EMP, CRPS, MPD and ENP among them.

Which pillow block series should you choose?

Choose the duty by the load rating the shaft needs, the base by the holes the frame offers, and the height by where the shaft has to sit. A standard-duty two-bolt block is the usual replacement; a medium-duty block answers a higher load in the same bore; a four-bolt base answers a frame drilled for four holes; and a low-base unit puts the shaft closer to the mounting surface, the Browning VPLS 200 at 1-5/16 inches to center on a 1-inch shaft against 1-7/16 on the VPS 200, and the Sealmaster NPL on the Sealmaster side.

Within a series the remaining choice is the shaft lock. Every unit in the tables locks with setscrews; the same housings are also offered with a concentric locking collar, the Sealmaster NP-T with the Skwezloc collar and the Browning VPB with the BOA collar, and Browning offers an eccentric collar, the VPE such as the VPE-220, which is designed for a single direction of rotation and is not for a shaft that reverses. Ball-bearing pillow blocks in these series end at a 4-inch bore; a larger shaft, or a load beyond a ball insert, moves to a tapered roller pillow block. Browse mounted ball bearings for the flange, take-up and hanger housings that share these inserts, or all mounted bearings by housing type. When the measurements do not land on a row above, send them through the support form and we will confirm the unit before you order.