A factory manager once told me bearings are boring until one seizes and shuts down his line. Fair point. I spend most of my week sizing, sourcing, and troubleshooting bearings for plants across NCR, and the mistakes I see are almost always the same handful. Let me walk you through the main types the way I'd explain it to a new maintenance engineer on their first day.
Deep Groove Ball Bearings: the workhorse
If I had to stock just one type of bearing, it'd be deep groove balls. 6200, 6300, 6400 series cover most of what Indian industry needs. They handle radial loads (the main job) and moderate axial loads in both directions. Electric motors, pumps, fans, conveyor rollers, gearboxes — you'll find 6000-series bearings in all of them.
Here's a rule I use: if the catalogue doesn't make the application sound special, start with a deep groove ball bearing. You're probably right. Only deviate if something about the load, speed, or space forces you.
Angular Contact Ball Bearings: for combined loads
When you have radial load and significant axial load in the same direction, angular contact (7200, 7300 series) is the right call. The contact angle (usually 15°, 25°, or 40°) sets the axial-to-radial balance. Higher angle = more axial capacity.
You'll see them fitted in pairs, either face-to-face or back-to-back, because a single angular contact bearing only handles thrust in one direction. Machine tool spindles and high-speed pumps are the classic applications.
Cylindrical Roller Bearings: heavy radial duty
Replace the balls with cylinders and suddenly your bearing can carry a lot more radial load in the same envelope. NU, NJ, and NUP series are the common ones in India. Heavy motors, rolling mills, vibrating screens, and big gearboxes all use these. The ring design (NU, NJ, NUP, N) determines whether the bearing can also take a bit of axial load or none at all.
Key advantage for maintenance: the inner and outer rings separate, so you can press one ring onto the shaft and the other into the housing independently. Much easier to fit than a non-separable ball bearing.
Tapered Roller Bearings: radial plus axial, both directions
The rollers are cones. This lets one bearing take heavy radial load and heavy axial load in one direction. Fit them in opposing pairs and you've got a setup that handles thrust either way, which is why they're standard in wheel hubs, truck axles, and gearbox shafts.
Common series: 30200, 32200, 30300, 32300. The critical thing with tapered rollers is preload. Too loose and they fret; too tight and they heat up and fail early. Follow the manufacturer's clearance spec when you fit them.
| Bearing type | Radial load | Axial load | Speed | Where you'll see it |
|---|---|---|---|---|
| Deep groove ball (62-series) | Medium | Low-Med | High | Electric motors, fans, pumps |
| Angular contact (72-series) | Medium | High (1 way) | Very high | Machine spindles |
| Cylindrical roller (NU, NJ) | Very high | Low | High | Rolling mills, heavy motors |
| Tapered roller (302/322) | High | High (both w/ pair) | Medium | Wheel hubs, gearboxes |
| Thrust ball (511/512) | None | Medium | Medium | Crane hooks, jack screws |
| Needle | High (compact) | None | Medium | Rocker arms, universal joints |
| Pillow block (UCP) | Medium | Low | Medium | Conveyors, agricultural gear |
Thrust Bearings: pure axial
Two flat races and balls or rollers between them. They don't handle radial load at all, so they're always paired with radial bearings. You'll see thrust ball bearings (51100, 51200 series) in crane hooks, turntables, and light vertical-shaft applications; thrust roller bearings (81200, 89300 series) take heavier loads.
Needle Bearings: big load in a small space
Imagine a cylindrical roller bearing where the rollers have been stretched into long thin needles. The contact area goes up, the radial height stays tiny. Perfect for connecting rods, rocker arms, universal joints, gearbox countershafts — anywhere you have the shaft size but no room for a full roller bearing around it.
Pillow Block Bearings (UCP): the ready-to-bolt-on unit
A UC-series insert bearing (wide inner ring with set screws) sitting inside a cast iron housing with a flat mounting base. You bolt it down, tighten the set screws onto the shaft, done. Shaft sizes from 12mm to 100mm are standard. Conveyors and agricultural machinery run on these. Not the most precise mounting, but for 90% of general industrial work they're quick and reliable.
How I actually size a bearing for a customer
When someone brings me a failed bearing or a new application, I ask:
- What's the load look like? Mostly radial, mostly axial, or combined?
- What RPM? Higher than 3000 starts excluding some types.
- What's the envelope? Shaft OD, housing ID, mounting constraints.
- Environment? Wet, hot, dusty, or corrosive — all drive seal and material choices.
- Service life expectation? L10 life of 10,000 hours is a different bearing than 40,000.
Stuck on a size or a replacement? Bring the failed bearing to Shri Narayan Machinery LLP at Sector 9, Noida, or send me a photo of the markings on WhatsApp (+91-9811104037). Most of the time I can identify it and quote the equivalent in minutes — SKF, FAG, NSK, or the value alternatives.