Here is another small quick adjust vise. This time by the Athol Machine Co. of Athol, MA. This is the same company that manufactured Laroy Starrett's first patent, a food chopper. Ultimately he wound up owning the company, but that is another story.
Interestingly the quick adjust feature was for a wood working vise rather than a bench vise. If you look at the two patents you will see that the first one required the operator to push down on the front of the vise in order to disengage the screw from the half nut. In the redesign, Mr. Simpson finally got it right. He moved the hall nut to the front of the fixed jaw so that by lifting up on the the bottom of the moveable you could position it where you wanted. A quick turn of the lever would then tighten the part between the jaws.
I'm not sure how large these were made. My biggest is two inches, and my guess would be that 3-4 in. would be maximum, otherwise the front jaw would be cumbersome to move. Keep in mind that the rear of the adjustment screw is fixed so that it can't move, only rotate. Therefore you have to be a little careful when setting it into the half nut. Something that would be harder to do as the vise got bigger.
For what it's worth these vises depart from the norm in another way in that they used a buttress thread rather than the Acme thread that is used on most other vises.
http://www.datamp.org/patents/displayPatent.php?number=119658&typeCode=0http://www.datamp.org/patents/displayPatent.php?number=4637&typeCode=1Mike
