| SELECT DISTINCT patent.*, YEAR(date) as year FROM patent LEFT JOIN category ON category.patent = patent.patent AND category.type = patent.type WHERE (category.class = '501') AND (category.subclass = '21') ORDER BY date ASC, patent, type |
Total of 3 patents found where: Class is '501'; Subclass is '21';
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| T / S | Patent | Date | Description | Patentee | Category | Assigned To |
| 1896 | ||||||
| U | 566,045 | August 18, 1896 | Insulator for Electrical Purposes Protective shield of metal with non-conducting enameled coating |
WHITAKER, Alfred J. P. TREHARNE, Frederick G. |
Protective Shield | |
| 1945 | ||||||
| U | 2,389,386 | November 20, 1945 | Glazed Ceramic Compression glaze |
RUSSELL, JR., Ralston |
Glaze | Westinghouse Electric Corp. |
| 1988 | ||||||
| U | 4,782,199 | November 1, 1988 | Insulators Having Improved Steep Wave Front Characteristics Suspension, head treated with special glaze to strengthen cap/cement |
SEIKE, Shoji TOTOKI, Takao MIMA, Toshiyuki |
Suspension | NGK Insulators, Ltd. |
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