This topic comes up from time to time. Some time back I conducted extensive research into the JH Williams Co after it was acquired by United Greenfield in 1958. I've forgotten some of the details since, but to the best of my recollection and records:
Sometime in the early 1960s, UG decided to start a truck tool line, and registered the VULCAN trademark in 1965. From the examples I've seen, Vulcan were essentially re-branded JHW tools, though I'm sure there were some tools unique to either line. The end wrenches I've seen all appeared identical to the JHW wrenches current at the time but just marked differently.
TRW acquired UG 1968 and was assigned the Vulcan trademark in 1969. It appears that the Vulcan truck tool line continued through that time.
I think that TRW ended the Vulcan brand tools and the tool truck distribution sometime in the late 1970s at the same time it had decided to re-position JHW as an industrial tool line and stop actively pursuing the auto mechanics trade. This was the end of the JHW Vulcan line.
TRW assigned the Vulcan trademark back to JHW when it divested itself of that company in 1984. There's no evidence that production/distribution of Vulcan branded tools ever re-commenced.
JHW changed to Williams Hand Tools in 1986, The Vulcan trademark was acquired from it by a DEEARBY CORP., a foreign company that appears to have registered in the USA specifically for this acquisition. Other assets may have been transferred at this time too. This is where Williams and Vulcan diverged from one another.
Williams went bankrupt in 1988 and was acquired by MLIF Acquisition, which then changed its name to JH Williams Industrial Products. It was under this company that the remaining JHW assets were liquidated. Snap-on acquired the remaining intellectual property (brand names, trademarks, patents, etc) from this entity in 1993.
Meanwhile, the Vulcan trademark was transferred by Deearby to a finance company Fleet Factors Corp in 1989. Reason for this is unclear but may have been part of a settlement for a defaulted loan. FFC sold the rights in 1990 to a TSC company that soon after changed its name to Post Tool. An importer based in Calif., from what I recall, Post intended to revive the Vulcan brand with imported product.
Apparently in another financial settlement, Post Tool transferred ownership of all its assets and intellectual property (including the Vulcan trademark) to BankAmerica Business Credit in 1996, no doubt from a business loan default. Then in 1999, BABC transferred the trademark from its Post Tool holding to BABC proper. That is where the trademark registration finally died as it was never renewed. It's free and clear today for anyone to claim it if they wanted to.