Per ICON insulator patent reference library this patent was assigned to JD March 27,1934 for a post insulator or stacker for assembling a switchgear mechanism.

Here is a photo of one of mine. It came off a large switch that I picked up in Montana some years ago. I had to disassemble it for the trip back to Oregon. Additional photos will show the switch as acquired and later disassembled.

These are uncommon in my experience but I have seen pieces here and there from Montana collectors/dealers at swap meets.