Those two (2) thingys are …. permanently mounted “quick-release” compression clamps.
They are mounted either in a vertical position with the hinged end at the top, … or at any angle down to a horizontal position. They are mounted by placing the “arm” with a hole in its center onto a steel “stud”, with the “stud” in the hole of the “arm”, and then the bolt was tightened which squeezed the “arm” tightly around the steel “stud”, thus firmly affixing the clamp in place.
To mount the clamp in any other position than describe above would make it extremely cumbersome to operate, …. like maybe the use of at least three (3) hands.
Whatever the clamp was meant to hold would be placed against or on the firmly affixed “arm” and then the hinged “arm” would be swung over top of it. Then the “quick release” handle would be swung up over the ends of the “arms” and snapped into place, thus firmly holding whatever was placed inside the clamp. Similar types of “quick-release” compression clamps were/are used on doors, lids, etc., such as the old “steamer” trunks.
And given the fact that those clamps are made of cast iron ….. then they have been around for quite a long time …… and whatever they were used on/for is most probably long gone. One might check old photographs of farming machines/equipment, old firefighting pumpers, wagons, engines, etc., ….. or etc., ….. for one of those clamps being used to hold an “item” in a handy place to get to.
