| Number | Name | Date | Kind |
|---|---|---|---|
| 3071123 | Gromme | Jan 1963 | |
| 3505983 | Hartel | Apr 1970 | |
| 4262639 | Motosugi et al. | Apr 1981 | |
| 4441464 | Toyoda et al. | Apr 1984 | |
| 4450793 | Sumiyoshi et al. | May 1984 | |
| 4674450 | Krajacich | Jun 1987 | |
| 4827882 | Paul et al. | May 1989 | |
| 5503124 | Wallis | Apr 1996 | |
| 5941206 | Smith et al. | Aug 1999 |
| Number | Date | Country |
|---|---|---|
| 719 510 | Apr 1942 | DE |
| 31 08 813 | Sep 1982 | DE |
| 31 42 891 | May 1983 | DE |
| 2 223 800 | Apr 1990 | GB |
| 9836158 | Aug 1998 | WO |
| Entry |
|---|
| Valkenburgh, “Electric Valves,” Road & Track, Jun. 1998, pp. 170-174. |