from The Century Dictionary.
- noun A lever having a drop or an offset to pass an obstacle or to bring the end to any desired point.
- noun A lever that drops or swings on a pivot, used to disengage the feed or stop any part of a machine.
Sorry, no etymologies found.
By the time he reached the fifth, there was no possibility of going back; the click of the drop-lever seemed to settle that.
A Collection of Stories, Reviews and Essays Willa Sibert Cather 1910