title graphic



Note: Detail description begins in Paragraph 13.

1. See the functional schematic diagram, Plate I. In this diagram several differentials are indicated. Actually only one of these is a spider type differential. The others are mechan- isms which perform the same function, i.e. add two quantities algebraically.


2. Note that the director pointer's telescope can be moved in elevation by three separate inputs:

3. The roller path compensator, having been properly set, automatically introduces to the director telescope the proper tilt correction for the existing angle of train.

4. Assume that everything is set on zero, with director telescopes and guns parallel to the "plane of the deck" (reference plane). The director range dial is so. graduated that, when the range is set, the director telescope is depressed the proper angle below the guns, i.e. the sight depression plus vertical parallax correction. This is equivalent to setting the sights on a gun: the gun telescope is depressed. Normally the sight depression is so large that, if the guns were not elevated above the plane of the deck, the director telescope would be pointed down at the water close to the firing ship. To be able to fire, the director pointer elevates his telescope until his crosswires are on the target. In doing this he changes the gun elevation order, so that the guns elevate, thereby remaining at the same angle above the director telescope.

5. From a study of the diagram it will be seen that the director maintains the proper relationship between the various angles:

Gun elevation
(above plane of deck)
 =  sight depression + vertical parallax correction + roller path correction
+ director telescope's elevation from plane of the deck.


The last quantity is "director correction". Omitting minor corrections, the above formula reduces to:

Gun elevation = sight depression + director correction.

6. In operating the director it is not necessary to know what these quantities are, but they exist nevertheless.


7. Setting the deflection offsets the director telescopes without changing the gun train orders. When the director trainer trains back to the target the gun train order is therefore corrected for the deflection set on the telescopes.

8. If there are two directors on the same side, a horizontal parallax mechanism (set for the range) offsets the telescopes of the after director the proper amount for the existing target bearing and range setting.

9. There are two transmitters in train. The coarse transmitter has graduations for 360° and is called the slewing transmitter because in slewing the director it is the only one used. It also used in normal training. The fine transmitter is graduated for only 6° and is called the "training11 transmitter. It is not moved when slewing.


10. The gun elevation order drives a pair of red pointers: coarse and fine. (only the fine pointer is shown. in the schematic diagram.) As the gun is moved in elevation it drives a corresponding pair of white pointers. It is only necessary for the gun pointer to match pointers.

11. As indicated in the diagram, provision is made for correcting for:

The elevation indicator is described in detail beginning in paragraph 26.

GUN TRAIN INDICATOR (or "Receiver").

12. Two red pointers, coarse ("slewing") and fine ("training") show the gun train order as received from the director. Two corresponding white pointers are driven by the gun in train. These pointers are offset by a parallax mechanism (set for range at each


Plate 1


indicator). When the gun trainer matches pointers he thereby offsets the gun in train to compensate for horizontal parallax between director and gun for the existing gun train and the range which is set. Horizontal parallax is usually referred-to in Vickers literature as "convergence". The train indicator or "receiver" is described n detail beginning in paragraph 29.


13. The Gun Director. (See Plate XVII).

The gun director is carried on a revolving table on top of a fixed pedestal. The pedestal is bolted to a machined surface on the deck. The train rack is secured to the pedestal. This train rack also contains a ball race, the balls supporting the entire revolving structure. The "principal elements of the director are conveniently referred to as:

14. Revolving platform or ring frame (or lower plate):

This contains the upper ball race and rests on the ball race. Lateral movement is prevented by a central train pivot. Carried in this element is the training mechanism and the convergence mechanism (when required). The eccentric crank of the convergence gear operates in a slot located in the "fixed base" (or upper plate) which is the next element above the ring frame and imparts to this plate a slight angular, motion to compensate for horizontal parallax. (Note: the "fixed base" is not fixed).

15. Fixed Base (or upper plate):
(Note: "Fixed Base" is a misnomer. It is not fixed.)

This plate provides a vertical pivot bearing for the main frame. On it is mounted the deflection mechanism. A movement of deflection gear imparts an angular motion to the main frame, thereby offsetting the telescopes.

Note: (Where no convergence gear is provided the fixed base and the ring frame described in (14) are combined in a single element).

16. Main Frame

This element is supported in a vertical pivot in the fixed base plate. It receives an angular motion with respect to the fixed base plate by the deflection mechanism. Supported on the main -frame is a horizontal pivot or shaft which provides a bearing for the intermediate arm and the telescope carrier. Mounted on the main frame is the range setting gear, scale and handwheel. A shaft from the range setting mechanism is geared to the intermediate arm, and moves the intermediate arm in elevation with respect to the main frame.

17. Intermediate Arm.

This element is pivoted on the horizontal pivot fixed in. the main frame. On the intermediate arm is mounted the elevation handwheel, roller path compensator and their associated


mechanisms. This mechanism communicates by means of a horizontal shaft to the telescope carrier, providing the means of elevating the telescope carrier with respect to the intermediate arm, and raising or lowering the telescope carrier with the intermediate arm when the latter is moved by a range setting.

18. Telescope Carrier:

This element is pivoted on the horizontal pivot fixed in the main frame. It supports the pointer's and trainer's telescopes. It's vertical motion is imparted by rotation and/or translation of the shaft connection from the intermediate arm. Where a stabilized sight is to be provided the telescope carrier on the trainer's side is finished off in the shape of a plate on which the stabilized sight is mounted.

19. A study of the foregoing elements indicates the following:

20. Cross level Element:

This element provided on some directors is designed to compensate for the error which comes into deflection due to tilted trunnions. It does not correct for elevation errors. For a detailed description of this mechanism, refer to O.P. 392. The compensation generated by this element is introduced by a movement of the deflection worm bracket on the fixed base, the action producing a deflection of the sight about the vertical- axis of the director. This element is not generally used, due to lost motion in the mechanism.

21. Elevation repeat Indicator:

Mounted on the intermediate arm and geared to the elevation handwheel is the Elevation Repeat. It indicates by means of two white pointers, mechanically the elevation transmitted to the guns. The two red pointers are driven by a motor on the elevation circuit. If the red and white pointers remain together, it may be assumed that the transmission gear is working satisfactorily. Actually it only indicates that there has been no interruption in the output of the transmitter. This does not prove that the motors at the guns are following, although it is a fairly reliable indication that they are. Inside the elevation repeat are the stops for the red pointer drive.

22. Train repeat Indicator:

Mounted on the ring frame is the train repeat indicator. Two white pointers are geared to the train rack. Two red


pointers are driven respectively by motors in the train and slewing systems. If the red and white pointers remain together, it may be assumed that the transmission gear is working satisfactorily.

23. Inclination Compensator (Roller Path): (See Plate XVII).

The compensator is mounted on the intermediate arm. It is a conventional compensator of the disc and crank type. The disc is driven by a flexible shaft connecting to the train pinion of the director. The crank pin is set off by the amount of the inclination. The inclination compensator lever causes a longitudinal movement of the elevating worm, the latter being connected by a splined shaft to the elevation gear.

24. Convergence Gear:

For details refer to O.P. 392. This mechanism provides a means for converging the director to the forward director on the same side.

25. In addition to the above elements there is mounted on the director:

26. The Elevation Indicator (or Receiver): (See Plates XLV, XLVI and XLVII)."

See figures of elevation receiver herewith. The elevation receiver is mounted at the gun pointer's station. Its white pointers are connected to the auxiliary elevation rack on the gun through shafts and gearing. There is provided an adjustable coupling for setting the white pointers.

27. The dip strip and dip setting mechanism are in the front part of the elevation receiver. See Plate XLV. The dip strip makes it possible to correct for velocity loss and for "dip", which is the vertical parallax between the gun and the standard gun (or mean gun level). Vertical parallax between director and mean gun level is corrected for in the graduations of the direc- tor range scale. To apply the correction the dip-setting handle is moved until the desired range on the strip is opposite the fixed index. This offsets the red pointer the required amount, so that when pointers are matched the correction will be applied. For detailed explanation see paragraph 30.


28. In the back of the instrument (See Plate XLVl) is the inclination, compensation gear. This gear is of the conventional disc and eccentric pin type. The disc is not oriented mechanically by attachments to the gun as might be supposed, but is operated by a motor on the "slewing" circuit. The movement of the eccentric pin is communicated through a cross head and differential gear to the white pointers. It should be carefully noted here that the inclination compensator is controlled by the slewing transmitter in the director.

29. The Train Indicator (or Receiver):

The train receiver is shown in Plate XLIX. It is mounted at the trainer's station (gun or searchlight), and is connected to the auxiliary training rack through shafts and gearing. An adjustable coupling, is provided for setting the white pointers, which are controlled by these attachments. The upper central dial is graduated in degrees (for 360°). The lower central dial is graduated in minutes (for 360'). The red pointer on the upper dial is driven by a slewing motor and tire red pointer on the lower dial is driven by the train motor. The motors are housed in compartments on the right side of the instrument case. A red cross is engraved at the zero point of each graduated dial. these are the points to which the red-pointers must be synchronized. Synchronizing is done by removing the caps on the motor chamber pushing in and turning the knobs. A scale of feet is graduated on the lower train dial. The angular (minute) graduation opposite this scale are the angles subtended at 10000 yards by the number of feet indicated on the scale. It is used for testing purposes.

30. To introduce convergence, i.e., to converge the gun on the forward director on same side, a correction is superimposed on the position of the white pointers. A convergence range scale appears in a small window on the upper left of the instrument. The scale is set by means of the Convergence handle. This scale is calibrated or graduated for each particular gun, depending upon its position with respect to the reference point in train. The details of this convergence mechanism may be obtained in O.P. 392. When the convergence range is set, the white pointers are offset. The training of the gun to again match the white pointers with the red electrical pointers will introduce the convergence in the gun.

31. Searchlight Deflection

The searchlight deflection eliminator is interposed in the mechanical drive between searchlight train rack and the train receiver. Since the train angle transmitted by the director is affected by gun deflection and since the searchlight should be directed without such deflection, the deflection eliminator provides the means for taking out such deflection and for introducing any other desired angular offset. Two scales appear in the


deflection eliminator, the upper is an arbitrary scale graduated from 0 to 9. The lower scale is a true deflection scale graduated from 0 to 99. Between the two scales is a double pointed index pointer reading to both scales and controlled by a knob. The deflection scale is moved by another knob. Normally the index pointer is set opposite 5 on the arbitrary scale and the deflection scale is moved so that the other pointer of the index is reading the actual deflection set on the director. With this set up, the deflection is entirely eliminated. The arbitrary scale permits of spotting the light right or left of the Director line of sight to produce the most effective illumination.



32. By synchronizing, we simply align the transmission system, that is, the motors are aligned with the transmitters, so that the quantities transmitted and the quantities registered by the motors are alike. To synchronize, proceed as follows:

33. At director.

Train director until the director clicks into the centering catch on zero. Director operator then reports "on zero train" and the order is given for guns to synchronize. The director pointer elevates with his handwheel to the stop in elevation, then depresses with his handwheel to the stop in depression. Then he brings his elevation to zero. This operation by virtue of the stop gears in each elevation indicator will synchronize the red elevation pointers in all elevation receivers and in the elevation repeat. When the director is back on zero elevation the red elevation pointers throughout the system should read zero The trainer having put his director on zero, sets the red pointers of the train repeat on zero by means of the knobs provided.


34. At Guns.

At the elevation receiver - the pointer synchronizes the inclination compensator train scale to zero reading by means of the knob on the slewing motor chamber. At the train receiver the trainer sets by means of the knobs the two red pointers to match the red synchronizing crosses on the degree and minute dials. The gun may be trained on any angle when synchronizing.


35. The range dial of the director is graduated down to 100 yards. As the range decreases, the graduations are more and more affected by dip until a range is reached at which the elevation correction due to dip becomes greater than the angular correction due to decrease in range; and the range graduations instead of approaching the zero mark, recede from it. Thus for the forward director on a certain ship the range at the forward director at which the elevation is a minimum is 1100 yards, and the least range for which the dial is graduated, 100 yards, coincides approximately with 7200 yards. The "zero" mark (i.e., the mark where zero would be on the scale were there no dip) is usually engraved on the dial.

36. The following table indicates how the scale graduations are arrived at for a director 70 feet above the mean gun level, with full charge.

Range Table
Dip Correction
for 70' base
Range Scale
from "zero"
2000 38'.5 42'.0 1° - 20'.5
1800 34'.2 44'.5 1° - 18'.7
1400 25'.9 57'.3 1° - 23'.2
1000 18'.0 1° - 20'.3 1° - 38'.3
600 10'.5 2° - 13'.6 2° - 24'.1
200 3'.4 5° - 50'.0 5° - 53'.4

37. Dip Strips on Guns:

Guns are supplied with a number of dip strips, which compensate for every 5 foot/second drop in muzzle velocity down to minus 200 f/s for full charge, and minus 150 f/s for reduced charge, Calibration of the dip strip is calculated as follows taking the strip which is to correct a 5 inch gun situated 20 feet below the mean gun level, and for a 50 f/s loss in M.V. The strips are in the form of a ring, and can only be assembled in one definite position. A white line (infinity mark) engraved on the rings is always in the same position relative to the pins which secure the strips. The index mark for reading this scale which is graduated


Range Additional Elevation
required to
overcome erosion,
Dip for
20 feet,
Required increase in
gun elevation,
5000 4.1 4.6 8.7
10000 13.6 2.3 15.9

in yards, is on the cover plate. One degree of the circumference of the strip is equivalent to one minute gun elevation and this is the scale by which the data of the last column is calibrated to the strips. On each side of the elevation receiver there is a dip-setting handwneel, which, by means of a mechanism .in the, receiver enables the dial to be revolved so as to bring the graduated range on the strip in line with the index mark. By making this adjustment the red pointers are moved with respect' to the white pointers through an amount necessary to correct for the difference between the muzzle velocity marked on the strip and. the standard muzzle velocity; also for the dip for the range set. When the gun is again laid to match the white pointers with the red, the required alteration to the gun elevation is effected.

38. Action cut out switchboard.

The switchboard provides for cutting out the instrument of any gun by opening a switch. It also provides means for throwing the guns of each broadside to either the forward or after directors.

39. Alignment of the System:

Alignment of the system is necessary in order that the director will be boresighted to the same target as the guns and the transmission system aligned so that when a director is pointed on a target at a selected range, and the pointers are matched at the guns, the gun sights will also check on the target, the sights having been properly set, both on the director and the guns. The alignment is affected as follows:


40. Test of Convergence Mechanism in Train Receiver.

Train the gun (searchlight) until it points directly toward or away from the director. This is the angle, of no convergence, and there should be no movement of the white train pointer while the convergence range scale is turned from infinity to the lowest indicated range. Next train the gun (searchlight) 90° from the above angle which will be the angle of maximum convergence. While on this angle of train turn the convergence range scale from infinity to 10000 yards and note the amount of movement of the train white pointer as Indicated on the scale of feet. This reading in feed should be equal to the horizontal distance in feet from the director to the gun (searchlight). Among the Ordnance blue prints aboard ship will be found prints which give the "broadside Battery Dip and Convergence Data". This data includes the distance from forward director to each gun on the same side, the bearing of maximum convergence, and the bearing of no convergence.


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