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Technical Data Sheet
PartsTable / COMPONENT / B21033C
B21033C ✓ Verified by PartsTable
— · TAPERED BEARING
WHAT YOU NEED TO KNOW
Cup and cone sold separately — confirm both needed Timken series numbers indicate dimensions
Cup and cone NOT sold as set — verify order
PRODUCT OVERVIEW

The BEARING,ROLLER,TAPERED is a the manufacturer tape media or drive component used in enterprise backup, archival, and disaster recovery environments. Key specifications include material: STEEL OVERALL, cup_width: 3.3125 INCHES NOMINAL IN, bore_diameter: 7.0000 INCHES NOMINAL IN, overall_width: 4.0625 INCHES NOMINAL IN, standout_width: 0.3750 INCHES NOMINAL IN, special_features: OIL HOLE AND GROOVE IN CUP. This product is currently in active production with full OEM support.

This part is cataloged in the Federal Logistics Information System (FLIS) under NSN 3110-00-120-1638, 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
B21033C
NSN: 3110-00-120-1638
FSC: 3110
CAGE: 24617 — GENERAL MOTORS CORP (USA)
SPECIFICATIONS
materialSTEEL OVERALL
cup_width3.3125 INCHES NOMINAL IN
bore_diameter7.0000 INCHES NOMINAL IN
overall_width4.0625 INCHES NOMINAL IN
standout_width0.3750 INCHES NOMINAL IN
special_featuresOIL HOLE AND GROOVE IN CUP
style_designatorSTRAIGHT BORE, DOUBLE CUP, SINGLE CONES, NON-ADJUSTABLE
cone_corner_radius0.1400 INCHES NOMINAL IN
backface_corner_radius0.0310 INCHES NOMINAL IN
overall_outside_diameter9.7500 INCHES NOMINAL IN
standard_tolerance_designationAFBMA CLASS 4
NSN3110-00-120-1638
COMPONENT DIAGRAM
TAPERED ROLLER BEARING — CUP & CONE ASSEMBLY CAGE CUP BORE CONE OD: — · BORE: — · WIDTH: — Single Row · PN: B21033C · OEM ⚠ VERIFY BEFORE ORDERING Cup and cone sold separately — verify you are ordering BOTH parts or the correct component. Always replace cup and cone together — mismatched wear = premature failure ✓ BROKER TIP Taper angle determines axial load capacity. Steeper angle = higher axial load rating. Timken series numbers indicate dimensions — cross-reference carefully PARTSTABLE TECHNICAL DRAWING — NOT TO SCALE
KEY FEATURES
•
CONE CORNER RADIUS: 0.1400 INCHES NOMINAL IN
•
CUP WIDTH: 3.3125 INCHES NOMINAL IN
•
STANDARD TOLERANCE DESIGNATION: AFBMA CLASS 4
•
STANDOUT WIDTH: 0.3750 INCHES NOMINAL IN
•
OVERALL OUTSIDE DIAMETER: 9.7500 INCHES NOMINAL IN
•
BACKFACE CORNER RADIUS: 0.0310 INCHES NOMINAL IN
TYPICAL APPLICATIONS
  • Long-term data archival and compliance retention
  • Offsite backup and disaster recovery
  • Air-gapped ransomware protection
  • Cold storage tier for infrequently accessed data
TECHNICAL CHARACTERISTICS (FLIS)
CONE CORNER RADIUS0.1400 INCHES NOMINAL IN
OVERALL WIDTH4.0625 INCHES NOMINAL IN
CUP WIDTH3.3125 INCHES NOMINAL IN
SPECIAL FEATURESOIL HOLE AND GROOVE IN CUP
STANDARD TOLERANCE DESIGNATIONAFBMA CLASS 4
STANDOUT WIDTH0.3750 INCHES NOMINAL IN
OVERALL OUTSIDE DIAMETER9.7500 INCHES NOMINAL IN
BACKFACE CORNER RADIUS0.0310 INCHES NOMINAL IN
MATERIALSTEEL OVERALL
BORE DIAMETER7.0000 INCHES NOMINAL IN
VERIFIED SUBSTITUTES & CROSS-REFERENCES 22
MIL-W-16878/4Interchangeable
interchangeable cross-reference
interchangeable
8-7-17Interchangeable
interchangeable cross-reference
interchangeable
MIL-S-16878/4Interchangeable
interchangeable cross-reference
interchangeable
MIL-DTL-81248Interchangeable
interchangeable cross-reference
interchangeable
GTP25Interchangeable
interchangeable cross-reference
interchangeable
4B4710Interchangeable
interchangeable cross-reference
interchangeable
LIFECYCLE
StatusACTIVE
AvailabilityOEM and secondary market
RoHS CompliantEAR99Not HAZMAT
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FREQUENTLY ASKED QUESTIONS
What is B21033C?
B21033C is a BEARING,ROLLER,TAPERED.
What parts can replace B21033C?
There are 22 known substitutes for B21033C: MIL-W-16878/4, 8-7-17, MIL-S-16878/4 and 19 more. Substitute compatibility should be verified for your specific system.
What is the NSN for B21033C?
B21033C is cataloged in the Federal Logistics Information System (FLIS) under NSN 3110-00-120-1638. 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