The Ring,piston, cataloged under National Stock Number 2805-00-147-8651, is classified within Federal Supply Class 2805 (Gasoline Reciprocating Engines, Except Aircraft; and Components) of the Engines, Turbines, and Components group. The manufacturer of record is Twin Disc, Incorporated Dba Twin Disc Mid-Atlantic. Government technical data includes 7 specifications, cited from the U.S. Government catalog. The record lists 1 manufacturer part number for this item, enabling identification through both NSN and commercial part number lookups. 1 additional reference document (drawings, advisory and superseded references) is recorded in the U.S. Government catalog. 1 item shares a part number with this NSN in the catalog (possible match — not a government interchangeability claim). Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 2805-00-147-8651 |
| Primary Part Number | M1904AQ |
| Item Name | Ring,piston |
| FSC / FSG | 2805 / 28 — Gasoline Reciprocating Engines, Except Aircraft; and Components |
| Manufacturer | Twin Disc, Incorporated Dba Twin Disc Mid-Atlantic |
| Status | ACTIVE |
| Cross-Sectional Shape Style | PLAIN RECTANGULAR, STRAIGHT FACE |
| Joint Style | INTERLOCKING JOINT |
| Radial Wall Thickness | 0.0940 INCHES MINIMUM AND 0.1040 INCHES MAXIMUM IN |
| Ring Style | CONCENTRIC |
| Surface Treatment | TIN OVERALL |
| Standard Bore Diameter | 2.250 INCHES IN |
| Material | IRON OVERALL |
| Acquisition Status | ACTIVE |
| DEMIL Code | DEMIL A — No Demilitarization Required |
| Hazard | No hazard code in the DLA record (HMIC N) |
| Criticality Code | X |
| Part Number | Manufacturer |
|---|---|
| M1904AQ PRIMARY | Twin Disc, Incorporated Dba Twin Disc Mid-Atlantic (USA) |
| Reference | Meaning |
|---|---|
| M1904AA TO 1904AZ | D/9 Drawing number reference only Twin Disc, Incorporated Dba Twin Disc Mid-Atlantic |
NSN 2805-00-147-8651 is a Ring,piston, manufactured by Twin Disc, Incorporated Dba Twin Disc Mid-Atlantic, classified under FSC 2805, Gasoline Reciprocating Engines, Except Aircraft; and Components. Status: active.
NSN 2805-00-147-8651 has 1 manufacturer part number on file: M1904AQ (Twin Disc, Incorporated Dba Twin Disc Mid-Atlantic).
1 possible match (shared part number, not a government interchangeability claim): 3040-00-363-5439. Verify interchangeability with system specifications before substitution.
Key specifications for M1904AQ: Overall Width: 0.0925 INCHES MINIMUM AND 0.0935 INCHES MAXIMUM IN; Cross-Sectional Shape Style: PLAIN RECTANGULAR, STRAIGHT FACE; Joint Style: INTERLOCKING JOINT; Radial Wall Thickness: 0.0940 INCHES MINIMUM AND 0.1040 INCHES MAXIMUM IN. 7 specifications are documented in the U.S. Government catalog.
No hazard code in the DLA record (HMIC N). Hazard information on this page is shown exactly as it appears in the DLA record.
U.S. Government catalog: edition PUBLOGDVD v12.0.0 (OCT 2026), edition date 2026-10-01, retrieved 2026-10-16.
U.S. Government catalog: edition PUBLOGDVD v12.0.0 (OCT 2026), edition date 2026-10-01, retrieved 2026-10-18.