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04-20657 — WASHER,FLAT

✓ Government record, cited
— · NUT WASHER
PRODUCT OVERVIEW

04-20657: WASHER,FLAT.

The WASHER,FLAT is a the manufacturer industrial component. Key specifications include material: STEEL OVERALL, thread_class: 3A A, hole_diameter: 12.5 MILLIMETERS NOMINAL MM, thread_direction: RIGHT-HAND, end_item_identification: 6115-01-561-7455 GENERATOR SET, DIESEL ENGINE, nominal_thread_diameter: 0.375 INCHES IN. This part is cataloged in the U.S.

Government catalog under NSN 5310-01-586-0557, 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
04-20657
NSN: 5310-01-586-0557
NIINs: 015860557, 015916658
FSC: 5310 — Nuts and Washers
CAGE: 30554 — DEPARTMENT OF DEFENSE PROJECT MANAGER-MOBILE ELECTRIC POWER (USA)
SPECIFICATIONS
materialSTEEL OVERALL
thread_class3A A
hole_diameter12.5 MILLIMETERS NOMINAL MM
thread_directionRIGHT-HAND
end_item_identification6115-01-561-7455 GENERATOR SET, DIESEL ENGINE
nominal_thread_diameter0.375 INCHES IN
thread_quantity_per_inch16
thread_series_designatorUNIFIED NATIONAL COARSE (UNC)
part_name_assigned_by_controlling_agencyBOLT, PLACE
NSN5310-01-586-0557
COMPONENT DIAGRAM
NUT & WASHER — GRADE MATCHING REQUIRED Hex NUT CROSS-SECTION WASHER OD: — SIZE: — MATERIAL: — PN: 04-20657 · 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
•
HOLE DIAMETER: 12.5 MILLIMETERS NOMINAL MM
TECHNICAL CHARACTERISTICS
PART NAME ASSIGNED BY CONTROLLING AGENCYWASHER (SNUBBING,HARDENED,12.5MM ID) MM
END ITEM IDENTIFICATION6115-01-561-7329 GENERATOR SET,DIESEL ENGINE,5.0 KW
HOLE DIAMETER12.5 MILLIMETERS NOMINAL MM
SUBSTITUTES & CROSS-REFERENCES 2
A026L575Same NSN cross-reference
Same NSN cross-reference
Also cataloged under this NSN
04-20655Reference document
Same NSN cross-reference
Reference document — Drawing number reference only
LIFECYCLE
NSN statusActive· U.S. Government catalog
No demilitarization required
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FREQUENTLY ASKED QUESTIONS
What is 04-20657?
04-20657 is a WASHER,FLAT.
What parts can replace 04-20657?
There are 2 known substitutes for 04-20657: A026L575, 04-20655. Substitute compatibility should be verified for your specific system.
What is the NSN for 04-20657?
04-20657 is cataloged in the U.S. Government catalog under NSN 5310-01-586-0557. This indicates validated use in U.S. government and defense supply chains.
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✓ PartsTable — the parts reference. Every fact cited to its source.
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.