| Number | Name | Date | Kind |
|---|---|---|---|
| 2846226 | Reynolds | Aug 1958 | |
| 3333851 | Rosen | Aug 1967 | |
| 3539188 | Salverda | Nov 1970 | |
| 3934881 | Gordfarb et al. | Jan 1976 | |
| 4343465 | Allen | Aug 1982 | |
| 4463949 | McCoy, Sr. et al. | Aug 1984 | |
| 4564191 | Atkin | Jan 1986 | |
| 4846468 | McCoy, Sr. et al. | Jul 1989 | |
| 5078031 | Hoff | Jan 1992 |
| Number | Date | Country |
|---|---|---|
| 0149562A2 | Jul 1985 | EPX |
| 2406463 | Jun 1979 | FRX |
| 444713 | May 1927 | DEX |
| 2200542 | Jul 1973 | DEX |
| 142556 | May 1920 | GBX |
| 2152826 | Aug 1985 | GBX |
| Entry |
|---|
| Popular Mechanics, Jan. 1963, pp. 162-163. |
| PCT International Search Report dated Jul. 29, 1996. |