A Training Receiver is a F.T.P. instrument mounted near a trainer's (or turret director trainer's) position which receives and indicates (usually by several red pointers) an angle of training transmitted by a director. The operator then works his controls to train the gun mount to bring the black pointers into alignment with the red.
A training receiver was required in each gun mounting or turret which would be fired under control of a director. Similarly, each separate gun generally required an elevation receiver to guide its gunlayer in matching the director.
British training receivers actually contained 2 receivers, as they were usually provided indication of the desired training angle through two circuits: a training circuit and a slewing circuit which supported much faster rates of training to find a target. The training receiver then might include a mechanism to correct the training angle for convergence in training to counter the distance between this gun mounting and the firing ship's datum point (the operator would enter the range to the target by a hand-wheel to permit this correction to be applied).
An Admiralty Order of late 1913 asks all British ships with turret F.T.P. gear (except Princess Royal) to report how often they've had to replace cabling to their receivers and whether they'd like to switch to having a junction box near the equipment so that the length of cables to the receivers that might wear out under motion could be reduced to simplify its replacement.
The British Director Firing Handbook, 1917 documents three types of training receivers.
Turret Type (Single Dial)
The single dial turret type had a spiral of 15 inches, allowing convergence angles of up to 1.5 degrees. In the Revenge class, this would permit the "B" turret to converge at 500 yards, but only permit the "Y" turret to converge at 3,000 yards, owing to their different distances from the convergence datum point. In earlier ships, the convergence scales were only marked down to 3,000 yards, but note was made that the scale was reciprocal and ships were welcome to mark them to closer ranges.
Turret Type (Double Dial)
To simplify the display, this design separated the minutes onto a large upper dial and the degrees to a small lower dial. Convergence range was set as on the single dial instrument, and lining up knobs on the right side placed the training knob above the slewing one, in accordance with the dial arrangement.
These were for guns 9.2-in and smaller, and had 2 dials for degrees (upper, smaller dial) and minutes (lower, larger dial). They were supplied with 2 spirals.
|Spiral Size||Pattern No.||Max Convergence|
The spiral in use could vary between various mounts on a ship, depending on their distance from datum point. This was the type used for flotilla leaders and destroyers, and were also adapted to use as searchlight bearing receivers.
Convergence range was set by a small handle on the face, reading against a small range scale seen to the left of the upper dial. On the right side, a pair of screw-caps covered the small knobs used to line up slewing and training receiver pointers (upper and lower).
The German director system must have had training receivers.
- Admiralty Weekly Order No. 653 of 21 Nov 1913.
- Director Firing Handbook, 1917, p. 11, Plates 47-49.
- Director Firing Handbook, 1917, Plates 50-52.
- Director Firing for Destroyers and Flotilla Leaders
- The Director Firing Handbook. Plates 53-55.
- Admiralty, Gunnery Branch (1917). The Director Firing Handbook. O.U. 6125 (late C.B. 1259). Copy No. 322 at The National Archives. ADM 186/227.
- Admiralty, Gunnery Branch (1918). Director Firing For Flotilla Leaders and Destroyers. Pub. No. B.R. 934 (late O.U. 6127 and C.B. 1461 and 1461(A). The National Archives. ADM 186/234.
- Admiralty, Gunnery Branch (1945). The Gunnery Pocket Book. B.R. 224/45. The National Archives. ADM 234/545.