The Piston,valve-Selector, cataloged under National Stock Number 2520-01-239-1175, is classified within Federal Supply Class 2520 (Vehicular Power Transmission Components) of the Vehicular Equipment Components group. The manufacturer of record is Twin Disc, Incorporated Dba Twin Disc Mid-Atlantic. Government technical data includes 3 specifications, cited from the U.S. Government catalog. The record lists 2 manufacturer part numbers 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through both NSN and commercial part number lookups. 1 additional reference document (drawings, advisory and superseded references) is recorded in the U.S. Government catalog. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 2520-01-239-1175 |
| Primary Part Number | B-1399-A |
| Item Name | Piston,valve-Selector |
| FSC / FSG | 2520 / 25 — Vehicular Power Transmission Components |
| Manufacturer | Twin Disc, Incorporated Dba Twin Disc Mid-Atlantic |
| Status | ACTIVE |
| Relationship to Similar Equipment | SIMILAR TO NSN 2520-00-902-1917 P/N B1399 |
| General Characteristics Item Description | STEEL AISI C1117; CASEHARDENED; 1.375 IN. O/A LG; 1.166 IN. MIN 1.176 IN. MAX INSIDE LG; 1.340 IN. MIN 1.350 IN. MAX STEP OD; 1.3726 IN. MIN 1.3730 IN. MAX SLEEVE OD; 1.0625 SLEEVE ID IN |
| Functional Description | PRESSURE RATE CONTROL PISTON |
| Acquisition Status | ACTIVE |
| DEMIL Code | DEMIL A — No Demilitarization Required |
| Hazard | Possible hazard — SDS may be required (DLA HMIC P) |
| Criticality Code | X |
NSN 2520-01-239-1175 is a Piston,valve-Selector, manufactured by Twin Disc, Incorporated Dba Twin Disc Mid-Atlantic, classified under FSC 2520, Vehicular Power Transmission Components. Status: active.
NSN 2520-01-239-1175 has 2 manufacturer part numbers on file: B1399A (Marine & Industrial Transmissions Ltd), B-1399-A (Twin Disc, Incorporated Dba Twin Disc Mid-Atlantic).
Key specifications for B-1399-A: Relationship to Similar Equipment: SIMILAR TO NSN 2520-00-902-1917 P/N B1399; General Characteristics Item Description: STEEL AISI C1117; CASEHARDENED; 1.375 IN. O/A LG; 1.166 IN. MIN 1.176 IN. MAX INSIDE LG; 1.340 IN. MIN 1.350 IN. MAX STEP OD; 1.3726 IN. MIN 1.3730 IN. MAX SLEEVE OD; 1.0625 SLEEVE ID IN; Functional Description: PRESSURE RATE CONTROL PISTON; End Item Identification: TWIN DISC HYDRAULIC TRANSMISSION MODEL TDC-20-2800. 3 specifications are documented in the U.S. Government catalog.
Possible hazard — SDS may be required (DLA HMIC P). 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.