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2M1778 — SEAT,HELICAL COMPRESSION SPRING

✓ Government record, cited
— · ORING SEAL
PRODUCT OVERVIEW

2M1778: SEAT,HELICAL COMPRESSION SPRING.

SEAT,HELICAL COMPRESSION SPRING. Key specifications include material: STEEL COMP 1213, design_type: SOLID, end_diameter: 0.8650 INCHES MINIMUM AND 0.8750 INCHES MAXIMUM IN, bore_diameter: 0.4920 INCHES NOMINAL IN, overall_height: 0.5000 INCHES NOMINAL IN, style_designator: SEAT. This part is cataloged in the U.S.

Government catalog under NSN 5340-00-853-6544, 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
2M1778
NSN: 5340-00-853-6544
FSC: 5340 — Hardware, Commercial
CAGE: 11083 — CATERPILLAR INC DIV CATERPILLAR DEFENSE (USA)
SPECIFICATIONS
materialSTEEL COMP 1213
design_typeSOLID
end_diameter0.8650 INCHES MINIMUM AND 0.8750 INCHES MAXIMUM IN
bore_diameter0.4920 INCHES NOMINAL IN
overall_height0.5000 INCHES NOMINAL IN
style_designatorSEAT
second_step_length0.5400 INCHES MINIMUM AND 0.5420 INCHES MAXIMUM IN
first_step_diameter1.2500 INCHES NOMINAL IN
chamfer_angle_in_deg45.0
countersink_diameter0.5410 INCHES NOMINAL IN
countersink_angle_in_deg45.0
distance_from_end_to_first_step0.4000 INCHES NOMINAL IN
NSN5340-00-853-6544
COMPONENT DIAGRAM
O-RING / SEAL — MATERIAL DETERMINES APPLICATION ID: — CROSS-SECTION CS: — SPECIFICATION Material: — Durometer: — Temp: — PN: 2M1778 MFR: OEM ⚠ VERIFY BEFORE ORDERING Wrong material = failure. Viton for oil/fuel, EPDM for water/steam, Buna-N for general purpose, Silicone for food-grade. Chemical incompatibility causes swelling, brittleness, or rapid degradation ✓ BROKER TIP Durometer (hardness) affects sealing pressure tolerance. Higher Shore A = harder = higher pressure. Standard durometer is 70A — verify if application requires different hardness PARTSTABLE TECHNICAL DRAWING — NOT TO SCALE
KEY FEATURES
•
COUNTERSINK ANGLE IN DEG: 45.0
•
FIRST STEP DIAMETER: 1.2500 INCHES NOMINAL IN
•
END DIAMETER: 0.8650 INCHES MINIMUM AND 0.8750 INCHES MAXIMUM IN
•
COUNTERSINK DIAMETER: 0.5410 INCHES NOMINAL IN
•
DISTANCE FROM END TO FIRST STEP: 0.4000 INCHES NOMINAL IN
•
DESIGN TYPE: SOLID
•
SECOND STEP LENGTH: 0.5400 INCHES MINIMUM AND 0.5420 INCHES MAXIMUM IN
TECHNICAL CHARACTERISTICS
OVERALL HEIGHT0.5000 INCHES NOMINAL IN
COUNTERSINK ANGLE IN DEG45.0
FIRST STEP DIAMETER1.2500 INCHES NOMINAL IN
END DIAMETER0.8650 INCHES MINIMUM AND 0.8750 INCHES MAXIMUM IN
COUNTERSINK DIAMETER0.5410 INCHES NOMINAL IN
DISTANCE FROM END TO FIRST STEP0.4000 INCHES NOMINAL IN
DESIGN TYPESOLID
SECOND STEP LENGTH0.5400 INCHES MINIMUM AND 0.5420 INCHES MAXIMUM IN
STYLE DESIGNATORSEAT
MATERIAL DOCUMENT AND CLASSIFICATIONQQ-S-637,COMP B1113 FED SPEC SINGLE MATERIAL RESPONSE
OTHER ITEMS IN FSC 5340 — Hardware, Commercial
Items in the same Federal Supply class. No interchangeability or substitution relationship is implied.
5340-00-000-0068 5340-00-000-0132 5340-00-000-8150 5340-00-001-1251 5340-00-001-1264 5340-00-001-1265 5340-00-001-1266 5340-00-001-1275
SUBSTITUTES & CROSS-REFERENCES 1
IPD2M1778Reference document
Same NSN cross-reference
Reference document — Secondary reference
LIFECYCLE
NSN statusActive· U.S. Government catalog
No demilitarization required
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FREQUENTLY ASKED QUESTIONS
What is 2M1778?
2M1778 is a SEAT,HELICAL COMPRESSION SPRING.
What parts can replace 2M1778?
There is 1 known substitute for 2M1778: IPD2M1778. Substitute compatibility should be verified for your specific system.
What is the NSN for 2M1778?
2M1778 is cataloged in the U.S. Government catalog under NSN 5340-00-853-6544. 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.