| Number | Name | Date | Kind |
|---|---|---|---|
| 1478805 | Tuttle | Dec 1923 | |
| 2575131 | Salkin | Nov 1951 | |
| 2651478 | Harris et al. | Sep 1953 | |
| 2690312 | Watson | Sep 1954 | |
| 3214112 | Sinquefield | Oct 1965 | |
| 3958776 | Torzo | May 1976 |
| Number | Date | Country |
|---|---|---|
| 1808945 | Sep 1970 | DEX |
| 1911348 | Sep 1970 | DEX |
| 2755915 | May 1979 | DEX |
| 1055402 | Oct 1953 | FRX |
| 1099627 | Jan 1968 | GBX |
| 1286583 | Aug 1972 | GBX |
| Entry |
|---|
| Merriman Ring Manual article, p. 10, "Winding Angles". |
| Saco-Lowell Twister Instruction Manual, p. 43, "Relation of Ring Diameter to Empty Bobbin Diameter for Good Running Work on Starting Up". |