Still don't exactly understand how it works but the item was "finally" found... whew. Patent no. 739,901 Sept. 29,1903.
Hay Tool Among other links:https://patentimages.storage.googleapis.com/pages/US739901-3.png
"Merlyn Irlbeck, Manning, Iowa, says that this piece was used with a rope sling for hauling loose hay on a hayrack; this was used as the "trip" to release the sling on one end after the hay was in the barn. "