https://www.datamp.org/ Recently added patents en-us https://www.datamp.org/patents/displayPatent.php?id=59809&pn=2,391,143 Wrench Patentee: August C. Ertner - Seattle WA Granted:1945-12-18

Quick adjust nut wrench with spring-tensioned latch of two or more plates to hold adjustment. Marketed as the ERTNER SPEED WRENCH. Lawsuits relating to the production of this wrench provide background details. Ertner was the inventor, and partnered with Frank Thorn to form Federal Trading Company to produce the wrench. They had forging and machining work done by contractors, and difficulties led to lawsuits. Corresponding Canadian patent CA-448,026 was granted April 20, 1948.
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