Common Bearings + Lubricants Reference
Why this matters
Bearing failure + lubrication issue are the most-common motor failures across HVAC, garage doors, appliances, + small engines. The tech who can identify a worn bearing by sound + replace lubricant correctly extends equipment life by years. This is the field card.
Bearing types
Ball bearings: balls between inner + outer races. Low friction, high speed, moderate load. Most common in motors + appliances.
Roller bearings: cylindrical rollers; higher load capacity than ball. Used in heavier equipment, wheel bearings.
Tapered roller bearings: cone-shaped rollers; handle radial + axial loads. Vehicle wheels, gearboxes.
Thrust bearings: handle axial (along shaft) load. Vertical shaft applications.
Sleeve / bushing bearings: simple cylindrical sleeve; oil-impregnated bronze (Oilite) OR plain brass. Older + lower-speed applications. Includes shaded-pole motor common in HVAC blowers.
Needle bearings: small-diameter rollers; high load in tight space. Universal joints, small motors.
Self-aligning bearings: tolerate slight misalignment; double-row.
Bearing sealing
Open: exposed; must be lubricated externally + protected from contamination.
Shielded (Z): metal shield reduces ingress; lubrication retained.
Sealed (2RS, 2NS): rubber/elastomer seal; lifetime lubricated; can't re-grease.
Most appliance + HVAC motors use sealed-for-life bearings: no maintenance possible; failure = motor replacement.
Common bearing sizes (ABEC system)
ABEC = Annular Bearing Engineering Committee.
ABEC 1: standard precision (most appliances).
ABEC 3: medium precision.
ABEC 5: precision (skateboard, RC).
ABEC 7+: high-precision (instrument, aerospace).
For service work, ABEC 1 OR 3 covers 99% of replacement.
Bearing size designation
Common 4-digit ID (last digits = bore size mm):
- 6200: bore 10 mm
- 6201: 12 mm
- 6202: 15 mm
- 6203: 17 mm
- 6204: 20 mm
- 6205: 25 mm
- 6206: 30 mm
- 6306: 30 mm with thicker section
First digit indicates series (load capacity): 6xxx = standard; 1xxx = self-aligning; 7xxx = angular contact.
Bearing failure signs
Sound: grinding, growling, squealing, knocking.
Vibration: feel motor housing; excess vibration during operation.
Heat: motor case warm-to-hot beyond normal.
Smoke: severe overheating; bearing seizing.
Visible damage on disassembly: pitting, discoloration, flat spots, missing balls/rollers.
Replacement procedure (general)
- Power off + lock out
- Remove motor / appliance to access bearing
- Mark orientation + photograph
- Pull bearing off shaft (puller required; never hammer on bearing race)
- Match new bearing exactly (number, sealing, fit)
- Press new bearing on (press on INNER race for shaft fit; OUTER race for housing fit; never load through balls)
- Reassemble + lubricate per spec
Bearing press / arbor press: critical for clean installation. Hammer + drift = damaged new bearing.
Common lubricants for service
Grease (thick, stays in place):
- NLGI 2 (most common): multi-purpose; lithium OR synthetic base
- NLGI 1: softer; cold weather
- NLGI 3: stiffer; high-temp
- Lithium complex: high-temp + water-resistant
- Calcium sulfonate: extreme conditions
- Polyurea: factory-fill bearings; high-temp
Common brands: Mobilith SHC, Lucas Red 'N' Tacky, Lubriplate, Mobil Grease XHP.
Oil (flows, lubricates moving parts):
- SAE 10W-30 motor oil: small engines (lawn mower, generator)
- SAE 30 non-detergent: older small engines
- 2-stroke pre-mix oil: chainsaws, 2-stroke engines
- Sewing machine oil: small precision mechanisms
- Light machine oil (3-in-1): door hinges, small mechanisms
- Penetrating oil (PB Blaster, Liquid Wrench): free seized fasteners; light lube
Specialty:
- Lithium spray (WD-40 specialist): clean lubrication, no drips
- Silicone spray: rubber + plastic compatible; non-staining
- Dry graphite lock-lube: door locks + cylinders
- Chain lube (motorcycle, garage door): clings + penetrates
- Heat sink compound: thermal transfer, not lubrication
- Dielectric grease: connector protection, not lubrication
NLGI grease grades
| NLGI | Penetration (1/10 mm) | Use |
|---|---|---|
| 000 | 445 - 475 | Pourable; gear case |
| 00 | 400 - 430 | Soft; lubrication |
| 0 | 355 - 385 | Multi-purpose extremely cold |
| 1 | 310 - 340 | Cold weather |
| 2 | 265 - 295 | Most common multi-purpose |
| 3 | 220 - 250 | Stiff; high temp |
| 4 | 175 - 205 | Very stiff; rare |
| 5 | 130 - 160 | Block grease |
| 6 | 85 - 115 | Hard grease |
For ball bearings: NLGI 2 standard.
Cold climate: NLGI 1 OR 0.
High-temp (oven motors, etc.): NLGI 2 with high-temp base (synthetic, polyurea).
Garage door lubricants
Spring (torsion): silicone OR lithium spray on coils.
Hinges + rollers: lithium spray.
Tracks: NO lubricant on inner track surface (dirt accumulates); only on roller bearings.
Chain drive opener: chain lube on chain only.
Belt drive: no lubrication needed.
HVAC motor lubrication
Sealed bearings: no lubrication possible.
Oilport (rare on newer): SAE 10W-30 non-detergent OR specific motor oil from manufacturer. 5 - 10 drops annually.
Most newer motors: sealed for life; lubrication issue = motor replacement.
Common lubrication mistakes
Wrong grease for application (mineral grease in food-grade equipment; petroleum in hydraulics where mineral required). Over-greasing (forces seal out; spreads inside motor). Under-greasing (dry running; bearing damage). Mixing grease types (incompatible bases congeal). Lithium + calcium-sulfonate sometimes incompatible. Silicone spray in friction reduction (deposits silicone film). WD-40 as lubricant (it's a solvent + light penetrant; not a long-term lube). Gear oil where chain oil required.
Bearing diagnostics
Spin freely with finger: no resistance, no grinding = good.
Audible: nothing = good; clicking = damaged; grinding = bad.
Side-to-side play: minimal = good; excessive = worn.
Heat after operation: bearing warm normal; very hot = bearing failing.
Vibration test: motor running, place stethoscope OR screwdriver tip to housing - clean hum = good; rough = bearing wear.
Truck stock for lubrication work
NLGI 2 grease tube (white lithium OR red lithium complex), grease gun (lever-style), oil cans (small can SAE 30 + light machine oil), silicone spray (lubrication + rubber), lithium spray (general bearing lube), penetrating oil (PB Blaster OR Kroil), 2-stroke oil (small engine), graphite lock lube.
When to grease vs replace
Re-greaseable (Zerk fitting, open OR shielded bearing): 1 - 3 pumps grease at service interval.
Sealed (most modern motors): replace bearing OR motor when noisy.
Grease nipple OR oil port present: maintain per OEM.
References
- NLGI Grease Education Center
- Manufacturer technical data (SKF, NSK, Timken, NTN, Mobil)
- Society of Tribologists + Lubrication Engineers (STLE)
- Manuall internal: Diagnostic Test Procedures, Common Pump Types