Chadburn's Turbine and Telegraph Tell-Tale
Chadburn's Turbine and Telegraph Tell-Tale was an electrical data system used to augment a mechanical engine room telegraph with an electrical indication of roughly what the turbine was actually doing: was it essentially stopped, was it moving ahead, or was it moving back?
At the telegraph end in the lower conning tower was a dial (Box "C" in the diagram) with sectors for "Ahead", "Stop" and "Astern". The dial had a red pointer and black pointer mounted concentrically: the red one was electrically driven to mimic the output signalling shaft of the mechanical engine room telegraph transmitter, and the black one (mounted atop the red one) was remotely driven by a transmitter connected to the turbine shaft through the mean speed gear. In this way, the red pointer would only be visible when a new order (at least when considered in terms of directionality) had not yet been matched by the turbine.
At the turbine end, the turbine itself was wired up with a transmitter which would send "Stop" (denoted by an open circuit) when the turbine were at lower than 10% maximum revolutions, and otherwise "Ahead" or "Astern" depending on its direction. A nearby lamp would indicate when the circuit was active (not sending "Stop"). The turbine also had a single dial with a black pointer indicating just as the black pointer dial at the telegraph end did: the turbine's indicated state.
- Annual Report of the Torpedo School, 1915. Plate 124.
- H.M.S. Vernon. (Jan 1916) Annual Report of the Torpedo School, 1915. C.B. 1166. Copy 1025 at The National Archives. ADM 189/35.