Throw switches and couples.
What does a Brake Holder do?
Throws switches and couples, or attaches to cable, cars being hauled by locomotive or hoisted by cable or chain in mines, quarries, or industrial plants: Uncouples loaded cars at their destination or uncouples and distributes empty cars to sidings or to loading areas. Moves switches to route cars and signals DINKEY OPERATOR to start or stop cars. May open and close ventilation doors in mines. May open or close chute gates to load or unload cars. May crush oversize rock or ore on grizzly to prevent clogging, using sledgehammer. May remove and tag ore samples for laboratory analysis. May be designated according to type of hauling machine as Dinkey-Operator Helper.