Industrial Ball & Roller Bearings

Industrial ball and roller bearings carry rotating shaft loads on rolling elements - balls, tapered rollers, spherical rollers, or needles - between hardened steel rings. Texas Belting stocks 6,500+ bearings and mounted units in Houston, TX, including 950+ radial ball bearings and 590+ tapered roller cups and cones.

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On this page: Decoder · Size chart · ZZ, 2RS & C3 · Interchange · Insert bores · Identify · Houston · Mistakes · FAQ

How do I read the number on my bearing?

The number stamped on a metric ball bearing encodes its size. In 6203, the 6 = single-row deep groove ball bearing, 2 = dimension series (light), and 03 = the bore code for 17 mm. For bore codes 04 and up, multiply the last two digits by 5: a 6208 has a 40 mm bore.

The second digit is the dimension series: 9 or 0 = extra light, 2 = light (6200), 3 = medium (6300) - same bore, bigger OD and width as it climbs. Suffixes (ZZ, 2RS, C3) are decoded below.

6200 and 6300 series bearing size chart

A 6203 bearing measures 17 mm bore x 40 mm OD x 12 mm width. The chart covers the two workhorse deep groove series: 6200 (light) and 6300 (medium). A 6300-series bearing shares the bore of its 6200 sibling but adds OD, width, and roughly 30-80% more dynamic capacity.

Dimensions are ISO standard. Cr values are typical published ratings for chrome steel bearings and vary by maker - confirm against the manufacturer's catalog.

What do Z, ZZ, RS, 2RS, and C3 mean?

The letters after a bearing number describe closures and clearance. Z means one metal shield, ZZ two; RS one rubber contact seal, 2RS two. Shields run faster with less protection; seals protect better at lower speed limits. C3 is not a closure - it marks extra internal clearance.

*Typical published speeds for a 6203-size bearing, grease lubricated; limits drop as size climbs and vary by brand. Standard nitrile seals are generally rated to about 100°C (212°F).

What C3 means: radial internal clearance one step looser than standard (CN). When the inner ring runs hotter than the outer - normal in electric motors - it expands and eats up clearance. C3 leaves room for that growth.

Bearing seal suffix interchange by brand

Major brands build metric ball bearings to the same ISO envelope, so the base number carries across brands - only the suffix language changes. A 6203-2RS crosses to SKF 6203-2RS1 (or 2RSH), NSK 6203DDU, NTN 6203LLU, FAG 6203-2RSR, Nachi 6203-2NSE, and Koyo 6203-2RS.

All of these brands mark extra clearance C3. Older Fafnir (Timken) numbers use PP for two contact seals: a 203PP crosses to a 6203-2RS.

Interchange references are based on manufacturer-published equivalents. Verify dimensions before ordering.

Insert bearing fractional bore chart

Insert bearings (UC series) are wide-inner-ring ball bearings with a spherical OD that fit pillow block and flange housings. The dash number is the bore in sixteenths of an inch: UC205-16 = 16/16 = 1 in. No dash means a metric bore by the same x5 rule (UC205 = 25 mm).

Identify your bearing with three measurements

Three caliper measurements identify almost any rolling bearing: bore, outside diameter, and width. Clean the old bearing, measure all three, and match the charts above. A 25 x 52 x 15 mm measurement is a 6205; a 1.0000 in bore with a wide inner ring and spherical OD is a UC205-16 insert.

1. Bore: inner ring ID. Clean metric (17, 20, 25 mm) points to the 6200/6300 chart; clean fractional (0.750, 1.000 in) to the insert chart or an inch R-series bearing.
2. OD: across the outer ring - this picks the series: 25 mm bore with 52 mm OD is a 6205, with 62 mm a 6305.
3. Width: across the rings. On inserts, record outer ring width, total width, and the locking style.

Copy every suffix from the old marking - closure (ZZ, 2RS), clearance (C3), snap ring groove. No match? Send the three measurements and a photo.

Industrial bearing supplier in Houston, TX

Texas Belting supplies ball and roller bearings from our Houston, TX warehouse. Most stocked sizes ship same day, and cross-reference quotes typically come back within one business day. We serve the Texas Gulf Coast and ship nationwide. Call (888) 203-2358 to confirm availability.

Common bearing selection mistakes

• Matching the base number and ignoring the suffixes. Replacing a 6205-2RS C3 with a plain 6205 gives up the sealing and clearance the application was built around.
• Assuming same bore means same bearing. A 6205 and 6305 share a 25 mm bore but differ in OD, width, and capacity. Measure all three dimensions.
• Putting a metric insert on a fractional shaft. 1 in = 25.4 mm; a 25 mm bore insert will spin and score a 1 in shaft. Use the dash-number bore (UC205-16).
• Replacing without asking why it failed. A bearing that ran hot may need C3; one that failed gritty may need contact seals or a better-sealed housing - not a fresh copy of the same part.

When to call instead of self-serve

The charts cover standard deep groove and insert sizes. Call when:

• You are sizing spherical or tapered roller bearings by load, speed, and life - not swapping a known number.
• The stamped number matches no chart (OEM specials, non-standard widths).
• The same position keeps eating bearings and needs root-cause help.
• The service is high-temperature, washdown, or chemical and the standard seal or grease may not survive.

Call (888) 203-2358 or send us what you have - a part number, three measurements, or a photo.

Frequently asked questions

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Last updated: July 2026