R188 Inch Bearing Dimensions and Identification
NSK R188 open-bearing dimensions: 6.35 mm bore × 12.7 mm outside diameter × 3.175 mm width. This inch-series single-row deep groove bearing has a separate shielded designation, R188ZZ, with a different width. This page compares those two NSK catalogue records; it does not establish another manufacturer’s equivalent.
NSK open-bearing dimensions
| Measurement | Millimetres | Converted inches |
|---|---|---|
| Bore | 6.35 mm | 0.25000 in |
| Outside diameter | 12.7 mm | 0.50000 in |
| Width | 3.175 mm | 0.12500 in |
The decimal inch values above are conversions of the recorded metric values, not independently verified nominal inch dimensions or manufacturing tolerances.
Open and shielded versions
| NSK designation | Closure | Bore × OD × width (mm) |
|---|---|---|
| R188 | Open | 6.35 × 12.7 × 3.175 |
| R188ZZ | Shields on both sides | 6.35 × 12.7 × 4.762 |
The bore and outside diameter agree, but the shielded bearing is wider. Check housing space, shaft shoulders and the full equipment specification before changing versions. ZZ describes the NSK shields in these cited records; it does not specify clearance or establish a universal seal-suffix translation.
Before ordering
Compare the full original marking, bore, outside diameter and width with the exact manufacturer record. Check closure, clearance, cage, lubrication and equipment requirements. Load and speed values are not reproduced here. Consult the exact NSK product record for its ratings, lubrication conditions and configuration. This page does not establish cross-brand interchange or current supplier stock.
Manufacturer sources and verification scope
NSK online product records reviewed on 15 October 2026: NSK R188 open bearing and NSK R188ZZ shielded bearing. The dimensions and closure descriptions above are supported by these records. Select the full clearance and tolerance designation for the application; these series-level sources do not approve a replacement or guarantee stock. Converted inches in the table derive from the recorded, rounded millimetre values and are not manufacturing tolerances.
Find and compare this size
Find R188 open-size dimension candidates or find R188ZZ shielded-size candidates. Check width as well as bore and outside diameter. Read bearing marking guidance and the seal and shield guide before comparing configurations.
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