| Number | Name | Date | Kind |
|---|---|---|---|
| 4110575 | Meisenheimer | Aug 1978 | |
| 4695686 | Merchant | Sep 1987 |
| Entry |
|---|
| Brochure-"Federal Supervisory Switches PIV/OSY", Federal Signal Corp.; Nov., 1986; 11 pages. |
| Bulletin No. 719; "PIVSU--A Post Indicator Valve Switch"; Potter Electric Signal Co.; Jul., 1984; 4 pages. |
| Bulletin No. 20E-16-1; "Supervisory Switches for OS & Y Gate Valves (Series NGV) and Indicator Post Valves (Series NIP)"; Notifier Company; Nov. 1978, 2 pages. |
| Bulletin No. 20E-16-3, "Supervisory Switch for Post Indicator Valves (PIV)"; Notifier Company; Aug. 1981, 2 pages. |