Link Belt3231PT3Two-Bolt Pillow Block with Self-Lubricating Carbon-Graphite Sleeve Bearing, 1-15/16 in Bore, Rated to 700 °F, No Grease Required

Product Description

What this part is

A Link-Belt Flex-Block 3200-series two-bolt pillow block fitted with a self-lubricating carbon-graphite sleeve bearing for a 1-15/16 in shaft. Cast iron housing, powder coated, with an alignable insert.

Correcting the source data — this is not a ball bearing:
The previous listing described this as a flange mount pillow block ball bearing. Two things are wrong and the second one matters enormously.

The P in 3231PT3 denotes a two-bolt base pillow block, not a flange — Link-Belt’s Flex-Block flange versions carry F or FX codes, so the flange unit at this size is 3231FXT3. And the T3 denotes a carbon-graphite sleeve: this is a plain bearing. There are no balls, no rollers, no cage, no seals and no locking collar anywhere in it.

Anyone expecting a rolling-element bearing will return it, so it is worth being blunt: this is a bushing in a housing. That is not a shortcoming — it is the entire point of the product, for the reasons below — but it has to be understood before ordering.

Decoding the designation

3200 — Link-Belt Flex-Block sleeve bearing series, alignable insert32 — series; 31 — size/shaft code, here 1-15/16 inP — Pillow block, two-bolt base. F and FX are the flange codesT3 — carbon-graphite self-lubricating sleeve, rated to 700 °F. The alternative is T1, an oil-impregnated sintered bronze sleeve rated to 200 °F

Note also that PT here has nothing to do with take-up units, which is an easy misreading. Link-Belt take-ups use T, TU and T3Y prefixes. And the ball-bearing pillow block family is P3U, an entirely different product.

Why choose a carbon-graphite sleeve — the 700 °F answer:
This is a specialist product with one dominant selling argument: temperature. Carbon-graphite is a solid, dry lubricant. It does not depend on grease or oil, so there is nothing in the bearing to cook off, carbonise, drain away or need replenishing.

That matters because a conventional greased ball bearing is finished well below 700 °F — most lithium-complex greases are done by around 300 to 350 °F, and above that the grease oxidises to a varnish, the bearing runs dry and it seizes. At 700 °F the T3 sleeve is still working. The applications follow directly: kiln and oven conveyor shafts, furnace and dryer fans, bakery ovens, foundry equipment, heat-treat lines, smoke and flue-gas dampers.

There is a second, quieter advantage. Because there is no grease, there is nothing to leak or to attract dust, and no relubrication schedule at all — genuinely maintenance-free. That is valuable in food and clean applications and in positions that are difficult to reach.

The trade you accept is real. A plain bearing has far higher running friction than a rolling-element bearing, tolerates much lower speeds, wants a hardened and ground shaft to run against, and wears progressively rather than failing by fatigue. If your position is cool and fast, a ball bearing is the correct and cheaper choice. If it is hot, this is one of the few things that works.

Published dimensions

Bore / shaft size: 1-15/16 inA, base to centreline: 2-1/4 inB, bolt hole spacing: 6-3/16 inC, overall length: 7-7/8 inL: 4-1/2 in; F, bolt size: 5/8 inWeight: approximately 7.2 lbHousing: cast iron, powder coated, alignable insertReplacement insert: 3231T3 (drop the housing suffix)

Load ratings and speed limits are not published in the Flex-Block dimension table — Regal Rexnord places them in a separate load ratings and speed limits section, and they are deliberately omitted here rather than estimated. On a plain bearing this is more than a formality: sleeve bearings are sized on bearing pressure and on the PV (pressure times velocity) product rather than on an L10 fatigue life, so the selection method is genuinely different from a ball bearing’s. Ask if you need the figures.

Fitting notes

The insert is alignable, so it accommodates a degree of initial misalignment between bearing seats. Because there is no locking collar or setscrew, the shaft runs directly in the sleeve bore — so shaft surface finish and hardness matter far more than they would on a ball bearing, and a rough or soft shaft will wear the sleeve quickly. There is nothing to grease; do not attempt to lubricate it, as adding grease or oil to a carbon-graphite bearing does not help and can trap abrasive debris against the running surface.

Interchange guidance

Cross-references: 3231PT3, 3231-PT3, 3231 PT3, 3231PT-3, LB 3231PT3. Insert only: 3231T3. Lower-temperature sleeve variant: 3231PT1 (sintered bronze, 200 °F). Flange version: 3231FXT3. Ball-bearing pillow block at similar size, a different product entirely: P3U231.

Obsolescence trail: Link-Belt mounted bearings are now part of Regal Rexnord, so current equivalents cross to Rexnord numbers. Four units are on hand — enough to fit both ends of two hot shafts from one batch.