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Technical Data Sheet
PartsTable / COMPONENT / MS21231-4
MS21231-4 ✓ Verified by PartsTable
— · BALL BEARING
WHAT YOU NEED TO KNOW
2RS = sealed for life, ZZ = shielded re-greaseable ABEC grade: higher = tighter tolerance
ABEC-1 standard, ABEC-7+ for precision spindles
PRODUCT OVERVIEW

The BEARING,PLAIN,SELF-ALIGNING is a the manufacturer industrial component. Key specifications include material: STEEL COMP 440C INNER MEMBER, bore_diameter: 0.2495 INCHES MINIMUM AND 0.2500 INCHES MAXIMUM IN, hardness_rating: 23.0 ROCKWELL C MINIMUM AND 35.0 ROCKWELL C MAXIMUM OUTER RACE MEMBER, style_designator: WITH INSERT AND/OR LINER, inner_member_width: 0.4350 INCHES MINIMUM AND 0.4370 INCHES MAXIMUM IN, outer_member_width: 0.3220 INCHES MINIMUM AND 0.3320 INCHES MAXIMUM IN. This product is currently in active production with full OEM support.

This part is cataloged in the Federal Logistics Information System (FLIS) under NSN 3120-00-937-9186, indicating validated use in U.S. government and defense logistics supply chains. Available through authorized enterprise resellers and TPM (Third Party Maintenance) channels.

Verify compatibility with your specific system configuration before ordering.

WHERE IT FITS
MS21231-4
NSN: 3120-00-937-9186
FSC: 3120
CAGE: 96906 — MILITARY STANDARDS PROMULGATED BY MILITARY DEPARTMENTS UNDER AUTHORITY OF DEFENSE STANDARDIZATION MANUAL 4120 3-M
SPECIFICATIONS
materialSTEEL COMP 440C INNER MEMBER
bore_diameter0.2495 INCHES MINIMUM AND 0.2500 INCHES MAXIMUM IN
hardness_rating23.0 ROCKWELL C MINIMUM AND 35.0 ROCKWELL C MAXIMUM OUTER RACE MEMBER
style_designatorWITH INSERT AND/OR LINER
inner_member_width0.4350 INCHES MINIMUM AND 0.4370 INCHES MAXIMUM IN
outer_member_width0.3220 INCHES MINIMUM AND 0.3320 INCHES MAXIMUM IN
static_radial_load_rating9000 POUNDS LBS
outer_member_outside_diameter0.6245 INCHES MINIMUM AND 0.6250 INCHES MAXIMUM IN
NSN3120-00-937-9186
COMPONENT DIAGRAM
BALL BEARING — SEAL TYPE DETERMINES MAINTENANCE OD: — · BORE: — · WIDTH: — SEAL: Open · PN: MS21231-4 · OEM ⚠ VERIFY BEFORE ORDERING ABEC grade: higher = tighter tolerance = higher cost. ABEC-1 is standard, ABEC-7+ for precision spindles. Open, shielded (ZZ), and sealed (2RS) versions have different max RPM ratings ✓ BROKER TIP 2RS = sealed for life (no maintenance). ZZ = shielded, re-greaseable. Open = must lubricate on install. Common interchange: 6205-2RS = 6205-2RSR = 6205-DDU (same bearing, different suffix) PARTSTABLE TECHNICAL DRAWING — NOT TO SCALE
KEY FEATURES
•
BORE DIAMETER: 0.2495 INCHES MINIMUM AND 0.2500 INCHES MAXIMUM IN
•
HARDNESS RATING: 55.0 ROCKWELL C MINIMUM INNER MEMBER
•
STYLE DESIGNATOR: WITH INSERT AND/OR LINER
•
MATERIAL: PLASTIC POLYTETRAFLUOROETHYLENE OR GLASS RACE LINER
•
OUTER MEMBER OUTSIDE DIAMETER: 0.6245 INCHES MINIMUM AND 0.6250 INCHES MAXIMUM IN
•
STATIC RADIAL LOAD RATING: 9000 POUNDS LBS
•
OUTER MEMBER WIDTH: 0.3220 INCHES MINIMUM AND 0.3320 INCHES MAXIMUM IN
TECHNICAL CHARACTERISTICS (FLIS)
BORE DIAMETER0.2495 INCHES MINIMUM AND 0.2500 INCHES MAXIMUM IN
HARDNESS RATING55.0 ROCKWELL C MINIMUM INNER MEMBER
STYLE DESIGNATORWITH INSERT AND/OR LINER
MATERIALPLASTIC POLYTETRAFLUOROETHYLENE OR GLASS RACE LINER
MATERIALSTEEL COMP 440C INNER MEMBER
OUTER MEMBER OUTSIDE DIAMETER0.6245 INCHES MINIMUM AND 0.6250 INCHES MAXIMUM IN
STATIC RADIAL LOAD RATING9000 POUNDS LBS
OUTER MEMBER WIDTH0.3220 INCHES MINIMUM AND 0.3320 INCHES MAXIMUM IN
MATERIALSTEEL CORROSION RESISTING OUTER RACE MEMBER
HARDNESS RATING23.0 ROCKWELL C MINIMUM OUTER RACE MEMBER
VERIFIED SUBSTITUTES & CROSS-REFERENCES 3
KR4-CWBInterchangeable
interchangeable cross-reference
interchangeable
MS21231-4Interchangeable
interchangeable cross-reference
interchangeable
AS14102Interchangeable
interchangeable cross-reference
interchangeable
LIFECYCLE
StatusACTIVE
AvailabilityOEM and secondary market
RoHS CompliantEAR99Not HAZMAT
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FREQUENTLY ASKED QUESTIONS
What is MS21231-4?
MS21231-4 is a BEARING,PLAIN,SELF-ALIGNING.
What parts can replace MS21231-4?
There are 3 known substitutes for MS21231-4: KR4-CWB, MS21231-4, AS14102. Substitute compatibility should be verified for your specific system.
What is the NSN for MS21231-4?
MS21231-4 is cataloged in the Federal Logistics Information System (FLIS) under NSN 3120-00-937-9186. This indicates validated use in U.S. government and defense supply chains.
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✓ Validated with multiple authoritative sources, including Government, OEM, and Certified sources.
PartsTable Design LLC · partstable.com
Last verified: July 2026