9 min read · 9 Jul 2026 · SLS Bearings India
Pillow Block Bearing Maintenance: Greasing and Alignment
A practical field guide to greasing pillow block bearings, calculating re-lube intervals and volumes, and aligning the housing to the shaft — so your UCP, UCF and UCT units reach their full service life.
Pillow block bearings (UCP, UCF, UCFL, UCT, UCC series) are the workhorses of conveyor lines, fans, agitators, harvesters and pumps across Indian industry. They are simple to fit — but nearly every premature failure we see traces back to one of two things: wrong greasing or poor alignment. This guide walks through both, with numbers you can use on the shop floor.
What a pillow block bearing actually is
A pillow block is an insert bearing (a wide-inner-ring deep groove ball bearing, usually UC-series with setscrew or eccentric collar locking) mounted inside a cast iron or pressed steel housing with a grease nipple, an integrated seal and — on most sizes — a re-greasable cavity. The housing is what does the aligning; the bearing insert is what does the rotating.
Because the bearing insert is spherical on its outside, the housing can accommodate a small amount of initial misalignment during mounting — but not continuous shaft deflection or a bent shaft.
Greasing: how often, how much
Why it matters
Grease in a pillow block does two jobs: it lubricates the raceways and it keeps water, dust and abrasives out through the seal lip. Over-greasing blows the seal. Under-greasing starves the rolling elements. Both fail the bearing in weeks, not years.
Frequency (re-lubrication interval)
Use this table as a starting point for standard UC inserts, 25–60 mm bore, in normal ambient conditions:
| Shaft speed | Clean, dry environment | Dusty / wet / high-vibration |
|---|---|---|
| Up to 500 rpm | Every 3 months | Every 4–6 weeks |
| 500–1500 rpm | Every 4–6 weeks | Every 1–2 weeks |
| 1500–3000 rpm | Every 1–2 weeks | Weekly |
| Above 3000 rpm | Weekly | Daily inspection, re-grease as needed |
Halve the interval if the ambient temperature is above 70 °C at the housing, or if the unit is washed down.
How much grease per shot
A common failure is "one full stroke of a grease gun per week" regardless of size — that is far too much for a small housing and far too little for a large one. Use bore diameter as the guide:
| Bore (d) | Grease per re-lube (grams) |
|---|---|
| 20 mm (UCP 204) | 1.5 g |
| 25 mm (UCP 205) | 2 g |
| 30 mm (UCP 206) | 2.5 g |
| 35 mm (UCP 207) | 3 g |
| 40 mm (UCP 208) | 4 g |
| 50 mm (UCP 210) | 6 g |
| 60 mm (UCP 212) | 8 g |
A standard hand grease gun delivers roughly 1 gram per stroke — so a UCP 208 needs about four strokes, not a full trigger pull. If in doubt, remove the drain plug (on housings that have one) before greasing so excess purges instead of pushing past the seal.
Which grease
For general industrial pillow blocks, use a lithium-complex NLGI 2 grease with an EP additive package. Do not mix greases with different thickener chemistries — lithium and polyurea, for example, can react and lose consistency. For hot service (>100 °C at the housing), step up to a polyurea or synthetic grease rated for the operating temperature.
Alignment: the failure mode nobody photographs
Even correctly greased pillow blocks fail early when the two housings on a shaft are not co-planar. Misalignment shows up as one raceway wearing more than the other, a running temperature 10–20 °C above the second bearing, and — eventually — a cracked outer ring.
Mounting sequence for a two-bearing shaft
- Set the fixed bearing (the one taking axial load) on the machined pad first. Snug the hold-down bolts, do not fully tighten.
- Slide the shaft through both housings without engaging the setscrews.
- Rotate the shaft by hand. Both housings should self-align on their spherical seats without any force.
- Set a straight edge or laser across the top of both housings. They must be parallel within 0.05 mm per 100 mm of shaft length.
- Fully torque the fixed bearing hold-down bolts to the manufacturer's spec (typically 25–30 Nm for M10, 50–60 Nm for M12).
- Tighten the setscrews (or eccentric collar) on the fixed bearing first, then the floating bearing. On setscrew locking, tighten in the direction of shaft rotation.
- Fully torque the floating bearing hold-down bolts last, so the housing can settle on its spherical seat without preloading the raceways.
The one thing to check monthly
Put your palm on each housing during the first ten minutes of operation. If one runs warmer than the other by more than about 15 °C, stop and re-check alignment before you re-grease. Extra grease on a misaligned bearing accelerates the failure, it does not fix it.
Common questions we get
How do I know if a pillow block bearing is failing? Rising temperature at the housing, a new grinding or ticking sound at shaft speed, visible grease weeping past both seals, and shaft end-float that was not there when it was installed. Any two of these together mean replace, not re-grease.
Can I replace only the insert and reuse the housing? Yes, for UC-series inserts, as long as the housing bore is undamaged and the spherical seat is not scored. Match the insert size code (e.g. UC 208) exactly.
What causes a pillow block bearing to keep failing in the same position? Almost always shaft deflection or a soft foot on the housing pad — not a bearing quality issue. Shim the housing pad flat and re-measure alignment.
Need pillow block bearings?
We import Chinese housing units (UCP, UCF, UCFL, UCT, UCC series) from 20 mm to 100 mm bore and stock the standard sizes. Send the shaft diameter, mounting type and quantity — we quote same day.
Talk to SLS Bearings India
Have a real bearing problem we should write about — or one we should solve? Reach our team.