from the GNU version of the Collaborative International Dictionary of English
- n. a contrivance by which miners ascend or descend in a shaft. It consists of a series of landings in the shaft and an equal number of shelves on a vertical rod which has an up and down motion equal to the distance between the successive landings. A man steps from a landing to a shelf and is lifted or lowered to the next landing, upon which he them steps, and so on, traveling by successive stages.
Sorry, no etymologies found.