Butterfly
Butterfly turns up in 2 fields: mining, shop slang. Here is what it means to the people in each one.
Butterfly in mining
A mechanical safety hook installed above a mine cage to prevent it from being pulled into the headframe sheaves.
This specialized safety device connects the winding rope to the conveyance in a vertical shaft. If the hoist operator fails to stop the cage at the surface landing, the device is drawn into a catch plate. The mechanism then shears a copper pin, releases the hoisting rope, and locks the cage safely in place to prevent a catastrophic fall or collision.
"Maintenance needs to inspect the butterfly and replace the shear pin before we resume manwinding operations on the main shaft."
Butterfly in shop slang
A quarter-turn valve that uses a rotating disc to control fluid flow.
A type of flow control device featuring a central disc mounted on a rod. When closed, the disc blocks the pipe completely, and when open, it turns sideways to let fluid pass. Mechanics and pipefitters favor them because they are compact, quick to operate, and cheaper than gate valves.
"Shut the main butterfly before you start unbolting that flange."