SealMasterST-54Wide Slot Take-Up Bearing Unit, 3-3/8 in Bore, Setscrew-Lock Ball Insert, Cast Iron, Non-Expansion

Product Description

What this part is

A Gold Line wide-slot take-up bearing unit: a one-piece cast iron take-up block with a self-aligning, setscrew-locking wide-inner-ring ball bearing insert already fitted. It is the moving element of a screw take-up assembly — the block slides in the guide rails of a take-up frame and an adjusting screw pushes it along to tension a conveyor belt or drive chain.

Decoding the order code

ST = standard-duty wide slot take-up unit, setscrew locking. 54 = the bore size code, here 3-3/8 in (85.725 mm). The insert on its own is catalogued as ER-54 (SealMaster 701095); SealMaster also calls it insert size code 2-36. The same 3-3/8 in insert appears in the SP-54 two-bolt pillow block, so if you are cross-shopping a rebuild, the bearing element is common between them and only the housing differs.

What decides whether it fits

Three things, in order. Bore: 3-3/8 in straight, tolerance -0.0015 to +0.0000 in, so the shaft must be to size and clean. Slot geometry: 1.813 in (46.05 mm) slot width on 6.813 in (173.05 mm) slot-to-slot centres — this is what has to match your frame rails, and it is the number people get wrong. SealMaster’s own STH-series wide slot frames are the designed partner. Adjusting screw: the boss on the bottom of the block takes the take-up screw and its square nut; check your screw diameter against the boss.

Non-expansion, and why that matters on a take-up

This is a fixed (non-expansion) unit — the insert is held axially in the housing, so it carries thrust and locates the shaft. On a two-bearing shaft you want one locating bearing and one that can float, or thermal growth in the shaft will preload the pair and cook them. On take-ups the usual practice is a fixed unit at each end of a pulley shaft that is short enough not to grow appreciably; on long shafts, plan the float somewhere else.

Sealing and lubrication

Felt labyrinth contact seals with a slinger at each end, plus a grease fitting for relubrication. The insert uses a brass land-riding retainer with generous pocket clearance, which lets grease circulate 360° around the balls rather than being scraped to one side — the practical benefit is a longer relube interval in dirty, dusty service. Factory charge is SealMaster GoldPlex-HP lithium complex EP NLGI 2. Setscrews are 7/16-20 UNF, diamond-faceted, spaced 120° apart; torque them 350-450 in-lb, alternately and in stages, and re-check after the first day of running.

Published ratings and mounting data

The ER-54 / 2-36 insert is rated 18,681 lbf (83.1 kN) dynamic and 14,496 lbf (64.5 kN) static, limiting speed 2,125 rpm. Ball inserts of this class carry lighter load than a spherical roller unit of the same bore but spin faster and cost far less — the trade is capacity and shock tolerance for speed and price. Misalignment capability is static only (±2°): the insert self-aligns as you bolt it up to take out mounting error, but it will not absorb a continuously misaligned or whipping shaft. If your take-up sees heavy shock or is a bulk-material head pulley, a spherical roller take-up is the right part instead.

Quantity and configuration

One take-up block with the insert installed. No take-up frame, no adjusting screw, no end caps.

Interchange guidance

SealMaster is a Regal Rexnord brand (SealMaster → Emerson Power Transmission → Regal Beloit → Regal Rexnord), so buyers searching Emerson or Regal Beloit SealMaster part numbers land on the same product. Also written ST54, ST 54, SealMaster ST-54. Adjacent bores in the same series are ST-51 (3-3/16 in), ST-52 (3-1/4 in) and ST-55 (3-7/16 in) — worth checking if your shaft is not 3-3/8 in.