Go-devil
Go-devil , noun
(a)
(Machinery) A weight which is dropped into a bore, as of an oil well, to explode a cartridge previously lowered.
(b)
(Machinery) A device, as a loosely fitted plug, which is driven through a pipe by the pressure of the contents behind the plug to clear away obstructions.
(c)
(Machinery) A rough sled or dray used for dragging logs, hauling stone, etc. [Local, United States]