Section 77.1904 - Communications between slope and shaft bottoms and hoist operators(a) Two independent means of signaling shall be provided between the hoistman and all points in a slope or shaft where men are required to work. At least one of these means shall be audible to the hoistman. Signal codes used in any communication system shall be posted conspicuously at each slope and shaft.(b) Signaling systems used for communication between slopes and shafts and the hoistman shall be tested daily.