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8724978 — NUT,SELF-LOCKING,EXTENDED WASHER

✓ Government record, cited
— · NUT WASHER
PRODUCT OVERVIEW

8724978: NUT,SELF-LOCKING,EXTENDED WASHER.

NUT,SELF-LOCKING,EXTENDED WASHER. Key specifications include material: STEEL COMP 4140 OR STEEL COMP 8640 OR STEEL COMP 8740 OVERALL, nut_style: HEXAGON, thread_class: 3B, thread_series: UNF, overall_height: 0.680 INCHES MINIMUM AND 0.700 INCHES MAXIMUM IN, hardness_rating: 26.0 ROCKWELL C MINIMUM AND 32.0 ROCKWELL C MAXIMUM. This part is cataloged in the U.S.

Government catalog under NSN 5310-00-655-9937, 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
8724978
NSN: 5310-00-655-9937
FSC: 5310 — Nuts and Washers
CAGE: 19207 — U S ARMY TANK AUTOMOTIVE COMMAND AMSTA-IM-MM (USA)
SPECIFICATIONS
materialSTEEL COMP 4140 OR STEEL COMP 8640 OR STEEL COMP 8740 OVERALL
nut_styleHEXAGON
thread_class3B
thread_seriesUNF
overall_height0.680 INCHES MINIMUM AND 0.700 INCHES MAXIMUM IN
hardness_rating26.0 ROCKWELL C MINIMUM AND 32.0 ROCKWELL C MAXIMUM
locking_featurePREVAILING TORQUE ALL METAL DESIGN
special_features125 MICROINCHES RMS ALL OVER EXCEPT 32 MICROINCHES RMS ON WASHER FACE
thread_directionRIGHT-HAND
washer_thickness0.110 INCHES MINIMUM AND 0.130 INCHES MAXIMUM IN
features_providedCASEHARDENED
width_across_flats0.865 INCHES MINIMUM AND 0.875 INCHES MAXIMUM IN
NSN5310-00-655-9937
COMPONENT DIAGRAM
NUT & WASHER — GRADE MATCHING REQUIRED Hex NUT CROSS-SECTION WASHER OD: — SIZE: — MATERIAL: — PN: 8724978 · OEM ⚠ VERIFY BEFORE ORDERING Grade matters for torque spec — don't mix grades. A Grade 5 nut on a Grade 8 bolt weakens the joint. Lock nuts, wing nuts, and castle nuts are NOT interchangeable with standard hex ✓ BROKER TIP Match nut to bolt thread class and material. Stainless bolt + zinc nut = galvanic corrosion. Always verify finish matches (plain, zinc, hot-dip galvanized) PARTSTABLE TECHNICAL DRAWING — NOT TO SCALE
KEY FEATURES
•
WASHER OUTSIDE DIAMETER: 0.990 INCHES MINIMUM AND 1.010 INCHES MAXIMUM IN
•
WIDTH ACROSS FLATS: 0.865 INCHES MINIMUM AND 0.875 INCHES MAXIMUM IN
•
THREAD SERIES: UNF
•
HARDNESS RATING: 26.0 ROCKWELL C MINIMUM AND 32.0 ROCKWELL C MAXIMUM
•
WASHER THICKNESS: 0.110 INCHES MINIMUM AND 0.130 INCHES MAXIMUM IN
•
MATERIAL DOCUMENT AND CLASSIFICATION: QQ-S-624 FED SPEC 1ST MATERIAL RESPONSE OR QQ-S-624 FED SPEC 2ND MATERIAL RESPONSE OR QQ-S-624 FED SPEC 3RD MATERIAL RESPONSE OVERALL
•
NUT COUNTERBORE DEPTH: 0.010 INCHES MINIMUM AND 0.030 INCHES MAXIMUM NUT IN
TECHNICAL CHARACTERISTICS
OVERALL HEIGHT0.680 INCHES MINIMUM AND 0.700 INCHES MAXIMUM IN
WASHER OUTSIDE DIAMETER0.990 INCHES MINIMUM AND 1.010 INCHES MAXIMUM IN
WIDTH ACROSS FLATS0.865 INCHES MINIMUM AND 0.875 INCHES MAXIMUM IN
THREAD SERIESUNF
HARDNESS RATING26.0 ROCKWELL C MINIMUM AND 32.0 ROCKWELL C MAXIMUM
WASHER THICKNESS0.110 INCHES MINIMUM AND 0.130 INCHES MAXIMUM IN
MATERIAL DOCUMENT AND CLASSIFICATIONQQ-S-624 FED SPEC 1ST MATERIAL RESPONSE OR QQ-S-624 FED SPEC 2ND MATERIAL RESPONSE OR QQ-S-624 FED SPEC 3RD MATERIAL RESPONSE OVERALL
NUT COUNTERBORE DEPTH0.010 INCHES MINIMUM AND 0.030 INCHES MAXIMUM NUT IN
FEATURES PROVIDEDCASEHARDENED
THREAD DIRECTIONRIGHT-HAND
OTHER ITEMS IN FSC 5310 — Nuts and Washers
Items in the same Federal Supply class. No interchangeability or substitution relationship is implied.
5310-00-000-0040 5310-00-000-0077 5310-00-000-0079 5310-00-000-1146 5310-00-000-3815 5310-00-000-4532 5310-00-000-4540
SUBSTITUTES & CROSS-REFERENCES 2
5310006559937Reference document
Same NSN cross-reference
Reference document — Secondary reference
CS-2300-0001Reference document
Same NSN cross-reference
Reference document — Drawing number reference only
LIFECYCLE
NSN statusActive· U.S. Government catalog
Acquisition advice: Normally procured from the manufacturer (OEM)No demilitarization required
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FREQUENTLY ASKED QUESTIONS
What is 8724978?
8724978 is a NUT,SELF-LOCKING,EXTENDED WASHER.
What parts can replace 8724978?
There are 2 known substitutes for 8724978: 5310006559937, CS-2300-0001. Substitute compatibility should be verified for your specific system.
What is the NSN for 8724978?
8724978 is cataloged in the U.S. Government catalog under NSN 5310-00-655-9937. This indicates validated use in U.S. government and defense supply chains.
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PartsTable Design LLC · partstable.com
U.S. Government catalog: edition PUBLOGDVD v12.0.0 (OCT 2026), edition date 2026-10-01, retrieved 2026-10-18.
PartsTable commercial catalog: edition Unified commercial catalog snapshot through 2026-09-28, edition date not on file, retrieved 2026-09-28.