"The Dewandre-Elco Power-Operated Machine Gun Turret," covers the PT boat power operated turret. This copy is marked PT-42.

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Richard Pekelney

Operating Instructions
The Dewandre-Elco Power-Operated Machine Gun Turret
Electric Boat Co.
Groton, Conn.


Description and Operating Instructions 1
General Description 2
Description of the Control 3
Description of the Training Mechanism 3
Description of the Elevating Arrangement of the Yoke 5
Description and Function of the Quick Release Valves 6
Compressed Air Supply 7
Working of the Turret - Relay Control 8
Rotation of the Turret 9
Elevating the Yoke 10
Vertical and Horizontal Simultaneous Operations 12
Adjustments - Shock Absorber and Mount 13
Adjustments - Training Mechanism 13
Adjustments - Lifting Valve 14
Piping 15
Piping - Filling the Hydraulic Side 16
Piping - Filling the Mechanism for the Relay Control 16
Piping - Filling the Reservoirs and the Training Cylinders 17
Piping - Filling the Power Cylinders and the Jacks 17
Locking and Securing the Turret 18
Maintenance 19


Title Sheet
General Arrangement 1
Schematic View - Operating Mechanism 2
Schematic Arrangement of Sheaves and Pulleys 3
Elevating Mechanism and Control Valves 4
Quick Release Valve 5
Piping - Compressed Air 6
Diagram showing Gun Ranges 7
Shock Absorbing Carrier 8
Piping - Air and Oil Training and Elevating 9
Piping - Relay Control and Filling Connections 10
Piping - Training Cylinders and Filling Connections 11
Piping - Elevating Cylinders and Filling Connections 12
Turret Locks 13


The turret is of the type in which a yoke carries a mount fitted for one or two machine guns, which yoke is suitably pivoted an a carriage of circular form. This carriage rotates on a circular track. With reference to the carriage and track the yoke with the mount may be bodily elevated in a vertical plane. In addition to this bodily elevation the guns are capable of a certain further amount of elevation end depression in any position in which the yoke may be. The carriage moving horizontally carries the guns irrespective of their positions in the vertical plane approximately 340 degrees, and also in any position of the carriage the guns themselves have a further movement to right and left. The main features of the turret are as follows:

1. Completely automatic. The gunner has only to manipulate the gun to aim at the target when the turret and the yoke follow all the movements of the gun sufficiently so that the aim can be kept on the target all the time.

2. The gun is connected to the mount on suitable rubber isolation fitting so that a certain amount of vibration is absorbed.

3. The pivots of the yoke on the circular carriage are so disposed that irrespective of its actual elevation the gunners head remains approximately in the position most suitable for sighting.

4. The motive power for operating the turret is compressed air at relatively low pressure needing small pipes and fittings. The air transmits pressure using oil as the hydraulic medium.

5. The turret is capable of being easily fitted on a suitable foundation as it is entirely self-contained excepting for the source of motive power. It can be removed and replaced on the foundation in a very short time.

6. The group of cylinders used for training the turret can be placed at any desired angle from the horizontal to the vertical depending on conditions to be met.

(Sheet I. Figure 1.)

On a stationary circular track 20 a carriage or ring 21 us operated by means of the hydraulic cylinders 22 acting through a system of wire ropes, pulleys, etc. A yoke 23 is pivoted at 24 on the carriage 21. The pivots form a horizontal axis. The hydraulic system of jacks 25 and 26 elevates this yoke. Gravity returns it to the lowest or any intermediate position.

The shock absorber system 30 pivots at 29 for elevation and is also capable of rotation horizontally though the medium of the vertical pivot supporting a Y-piece carrying the guns. The turret has weather protection in the shape of a cupola of semispherical form, built up of transparent plastic material on suitable frames. The cupola has an aperture through which the guns chase protrudes fitted with a sliding transparent closure moving with the gun during elevation.

The gun le fitted to a mount 30 by means of two shackles 33 and 34. The lower bolt of shackle 33 is rubber fitted and during

firing a certain amount of rotational movement against the resistance of the rubber is caused. This isolates shocks between the gun and the yoke.

(Sheet II. Figures 2 and 3)

To enable the movement of the gun to control the turret a hydraulic transmission is used between the moving and stationary parts of the turret and its foundation. A lever is attached to the fork carrying the gun which, when the gun is moved, displaces a piston 38 in relay cylinder 39. This assembly is on the movable part of the turret. Pipes 40 and 41 connect cylinder 39 to cylinder 42 mounted on the stationary or foundation part of the turret. In this cylinder a piston 43 follows the motion of piston 38 and in turn moves a camshaft 45 through lever 44. The cams operate the means governing the training action.

(Sheet II. Figures 2, 3 and 4)

NOTE: In figure 2, sheet II, the various parts are shown schematically for simplification. In fact the lever 44 Is located between the cam 46 and 47 as shown in figure 4. By means of the lever 50, carrying rollers, the cam 46 actuates one or the other of the valves 48 and 49 according to its direction of rotation. Each valve is composed of a release valve 51 and an admission valve 52. both fitted with return springs. The passage 53 is connected with the atmosphere.

Passages 54 and 55 are connected to the source of compressed air. The pipes 56 and 57 ere respectively connected with the reservoirs 58 and 59 by means of a quick release valve 60 - 60. The latter is described on page 6 and shown on sheet V. The opening of valve 46 or 49 respectively places under pressure the oil contained in the reservoirs 58 end 59. It is to be noted that the valves 48 and 49 are always in an opposite condition i.e., when one is admitting compressed air, the other one is open to the atmosphere.

By means of the levers 63, carrying rollers, the cam 47 simultaneously actuates the progressively opening valves 61 and 62, adjusted alike. For the valve 61, circuit 126 lead to and from the reservoir 58 and circuit 128 to and from cylinder 65. This cylinder trains the turret in one direction. In the valve 62 circuit 127 leads to and from the reservoir 59, and circuit 129 to and from the cylinder 66. This cylinder trains the turret in the opposite direction. Both valves 61 and 62 have a conical end 64. This conical or taper end of valve 61 opens or closes the passage of the oil from the reservoir 58 to the cylinder 65, and similarly the valve 62 opens or clones the passage or the oil between the reservoir 59 and the cylinder 66. The taper of these valves controls the flow of the oil and therefore the speed of the turret's rotation.

The motion of the pistons 67 and 68 is transmitted to the movable ring 21 through cables 69 and 70 running over pulleys (sheet III). The cables 69 and 70 are symmetrically placed in relation to the longitudinal axis AB.

In order to simplify the description let us consider the cable 69 alone. Its travel is six times greater at the pulleys attached to the movable carrier 71 than at the pulleys 76 and 78 secured

to the fixed portion of the cylinder assembly. Its tension is adjusted by 73. The pulley 80 is secured to the cylinder assembly. The pulleys 81 and 82 are located on the stationary ring. The arrangement of those 3 pulleys permits the training cylinder assembly to be mounted at any angle between the horizontal and the vertical position.

The path of the cables is easily followed in figure 5. For instance, the cable 69, anchored at 74, successively passes over the pulleys 75, 76, 77, 78, 79, 80 and 81 finally being secured to the movable ring 21.

The arrangement of the cable 70 is similar to that of the cable 69. A cable 83, passing over the pulley 84, connects the pistons 67 and 68. When the turret is rotating, the cable 83 is not under tension.

(Sheet IV. Figures 6, 7 end 8)

Cams 85 and 86 moving with the gun have their center of rotation at 29 which is the axis on which the gun rotates in fork 27.

The cam 85, by means of the lever 88, carrying a roller, operates the push rod 90 which slides in the body of the fork 27. The fork can rotate on a vertical axis in the support 28. The push rod 90 actuates the valve 91. The latter is composed of a member 92 in direct contact with a release valve 93 and an inlet valve 94. Both valves have return springs. The aperture 95 leads to the atmosphere. The passage 96 is connected with the source of compressed air. The passage 97 communicates, by means of the quick action valves

60 with the power cylinders 98 and 99 whose action is to compress the oil contained in the cylinders 100 and 101. The latter are connected together through a pipe 102. The cam 86 by means of lever 89, carrying a roller, operates the push rod 103 which slides in the fork 27. The push rod 103 actuates the progressively opening valve 105. The latter has a conical end which opens or interrupts the flow or the oil between the passages 106 and 107. The passage 106 receives the oil from thy cylinders 100 and 101. The passage 107 is connected to the jacks 25 and 26 causing the rise of the yoke.

The angle of the conical and 105 controls the flow of the oil between the cylinders 100 and 101 and the jacks 25 and 26, and thus controls the speed of elevation of the yoke.

NOTE: (a) Moving in either direction, the cam 86 actuates the push rod 103 and operates the conical and 105 for the rise as well as for the fall of the ring; whilst the cam 85 actuates the push rod 90 only to operate the rise. Cam 85 does not operate the release valve to lower the yoke.

b) The cylinders 98 and 100 and 99 and 101 constitute the arms of the yoke.

(Sheet V.)

As will be seen from sheets XI and IV, the reservoirs 58 and 59 as well as the cylinders 98 and 99, which are respectively the motive means for the rotation of the ring and the pivoting of the yoke, are both fitted with a quick release valve 60. This valve permits a rapid venting of the compressed air and thus an immediate

stoppage or reversal of the ring's rotation as well as of the movements of the yoke.

The valves are composed of a short stroke piston 108 on the head of which a valve 109 is fitted whose stem 110, guided in the piston, carries at the bottom end a second valve 111. A spring 112 normally holds the valve 109 on it seat. The aperture 113 leads to the atmosphere. The passage 114 is connected to the compressed air. This passage 115 leads to the chamber 116 of the oil cylinder (figure 9).

When the distributor is opened, the compressed air entering passage 114 actuates piston end valves. When the valve 111 is seated, the piston 108, moving further leaves the vale 109 and establishes communication between the distributor and the chamber 116. The reservoir is thus subjected to air pressure (figure 10).

When, by the action of the distributor, the pressure is vented through the passage 114, the piston 108 is instantaneously forced back under the action of the compressed air from the reservoir and carries with it the valves 109 and 111. The compressed air can then directly and rapidly vent through the aperture 113 without passing thorough the pipe connecting the reservoir with the distributor.

(Sheet VI )
(Not Furnished with Turret)

The motive power for operating the Turret consists of compressed air. Two methods of providing air are shown on the above sheet.

First Method - Fig 11-a

An air flask, 119, having a capacity of 1 to 2 cubic feet

(1 cubic foot gives about 120 and 60 complete elevations and training cycles respectively) is charged from the parent vessel or shore supply to a pressure of 2100 pounds per square inch. A reducing valve 87, is placed in the line between the flask and the service to reduce the air pressure to 150 pounds per square inch.

Second Method - Fig. 11-b.

An air compressor, 117, electrically or engine driven, having capacity of 10 cubic feet of free air per minute supplies air to a flask, 119, of 1 cubic foot capacity at maximum pressure of about 240 pounds per square inch. When the air pressure in the flask falls to 150 pounds per square inch, the air compressor automatically starts and recharges it.

(Sheet II.)

Neutral Position- The constituents as shown on figures 2 and 3 are in the neutral position, that is, when the longitudinal axle of the gun coincides with the center line of the yoke. Then the lever 36, part of the gun carrier, does not exert any action on the controlling piston 36. Thus the piston 43 maintains the earn lever 45 in the neutral position.

Working. If the gun is moved to the right (arrow C) the lever 36 moves the piston 38. The oil is pushed from chamber 121 to the pipe 40 into chamber 122 against the piston 43 which causes lever 44 to rotate the camshaft 45 to the right (arrow D).

While this action is taking place, the oil contained in the chamber 124 of the cylinder 42 passes to the chamber 123 of the controlling cylinder 39. The action is reversed if the gun is moved to the left.


(Sheet II.)

In figures 2 and 3 the control is shown in neutral position in which the cams 46 and 47 are operating neither of the valves 48 end 49 nor the valves 61 and 62. Therefore the reservoirs 58 and 59 are open to the atmosphere. The circuits 126 to cylinder 65, and 127 to cylinder 66 are closed by the valves 64.

Working. It has been explained previously (Relay Control) that when the gun is moved to the right, the camshaft 45 receives a similar motion. The result is first - the cam 46 moves the release valve 51 against the admission valve 52 closing the connection of the reservoir 58 with the atmosphere; second - the valve 52 is opened and the reservoir receives from passage 54 compressed air through pipe 56. The oil in the reservoir is thus subjected to air pressure. At this stage the oil passage between the reservoir 58 and the training cylinder 65 is still closed, the profile of the cam 47 being such that the valve 64 is operated only after the inlet valve 52 has been opened. When this opening has taken place the cam 47 allows the conical end 64 to leave its seat and to establish through the conduit 126 the flow of the compressed oil from the reservoir 58 to the cylinder 65.

The piston 67 can thus move and by means of the cable system shown on sheet III cause the turret to rotate to the right.

In the course of the description of the training mechanism it was stated that the adjustment of the valves 61 and 62 were exactly similar and that they were simultaneously actuated by the cam 47. Thus when the turret is revolving to the right, the oil

passing through the valve, is pushed from the reservoir into the cylinder 65 whilst the oil, which is in cylinder 66, travels to the reservoir 59, passing through the valve 62. Air which is on top of the oil in reservoir 59 vents to the atmosphere via the quick acting valve 60.

It must be noted that the speed of rotation of the turret depends on the lift of the valves 61 and 62.

A motion of the gun to the left produces the action described in a reversed manner.

Stopping the turret. When the rotation of the turret has brought the gun in the direction of the target, the gunner maintains the gun in that direction; the turret pursuing its rotation causes the valves to be returned to the neutral position and the turret automatically stops.

(Sheet IV.)

Neutral Position. The control as shown in figures 6, 7 and 8 is in the inoperative position, that is, when the guns axis E.F. is at right angle to the pivoting axis G.H. of the fork 27, the cam 85 has then no action on the valve 91; the cam 86 is also not operating the valve 104.

The power cylinders 98 and 99 are then in communication with the atmosphere and the passages 106 and 107 connecting the oil cylinders 100 and 101 to the jacks 25 and 26 ere closed by the valve 105.

Action of Lifting. When the gun is pivoted at 29 in the direction of the arrow M in order to aim at a target, the cam 85 being all one with the gun, the lever 88 actuates the rod 90 which lowers the member 92 against the release valve 93.

The result of this operation is: First - to press the release valve 93 on the inlet valve 94 and close the communication with the atmosphere of the cylinders 98 and 99 controlling the lifting of the yoke. Second - to open the inlet valve 94 which connects the cylinders with the source of compressed air. At this stage the communication between the oil cylinders 100 and 101 and the jacks 25 and 26 is not yet established, as the shape of the cam 86 is such that it operates the rod 103 end the conical end of valve 105 only after the inlet valve 94 has been opened. It is only then that the cam 86 allows the valve 105 to leave its seat, permitting the passage of oil from the cylinders 100 and 101 to the jacks 25 and 26 and the lifting of the yoke.

The speed of elevation depends upon the amount of oil passing. The size of the passage opened by the conical end of valve 105 controls the speed of the lift.

Operation of Lowering the Yoke. When the yoke is at a standstill in any elevated position, if the gun is being pivoted downward at 29 in the direction of the arrow N, in order to aim at an object, the cam 85 does not act upon the push rod 90 end thus does not effect the inlet valve 91.

Consequently when the yoke is being lowered the power cylinders 98 and 99 remain In communication with the atmosphere. The

weight of the yoke together with the gun's weight causes the lowering as soon as the cam 86, through the push rod 103, permits the conical end of valve 105 to leave its seat and open the passages 107 and 106. The oil, which is in the jacks 25 and 26 is then pushed back into the cylinders 100 and 101. The speed of the fall is a function of the degree at opening of the cone.

To Stop the Yoke. When the gun by means of the movement of the yoke is pointed towards the target it is necessary to hold the gun in that direction. The yoke continuing its downward movement brings the controlling mechanism back in the neutral position, both in the rising or falling action, and the yoke is thus automatically stopped

(Sheet VII.)

In the preceding description the movements of the turret and the yoke have been explained separately.

It will be readily understood that the two actions can take plans at the same time, as the control of one does not interfere with the other. Thus an oblique movement imparted to the gun will simultaneously operate both controls for the training and elevation. The yoke can be elevated through an angle of 53° from the horizontal. The gun can be elevated in the yoke through an angle of 32° which makes a total lift of 85°. On the other hand the gun can be depressed 16° from the horizontal (figure 12).

The turret can rotate 170° each side from the boat's transversal axis O.P. Moreover the gun has also a free movement of 20° either side of its pivot. (figure 13.)

Figure 13 indicates the position of the two turrets on the boat. At 22 and 22' are shown the places of the training cylinders and their reservoirs. On the other hand O'P' represents the longitudinal axis, the front being shown by the arrow.

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
(Sheet VIII)
Figure 14

Shock absorber 33 consists of an outer and inner cylinder 33a connected through a shock-absorbing medium 33b. Arms on the outer cylinder are attached to the gun while an arm of the inner cylinder is secured to the gun mount 30. Vibrations due to recoil when firing, are thus absorbed.

No adjustments are necessary on this shock absorber or mount.

(Sheet II.)

In the description of the training of the turret it has been explained that the cam 46, according to direction actuates one or the other of the valves 48 and 49 by means of the lever 50.

It will be seen that the release valve 51 of each control carries a screw 135 and lock nut 136. This arrangement serves to adjust he valves while assembling. The operation is made as follows: 1st - Fix the cam shaft 45 in its neutral potion by means of the peg 137 pushed into the bearer 133 and the hole 139 of the lever 44 (figure 4).

2nd - Bring the roller of the lever 50 In contact with the cam 46, by means of the adjusting screw 135 carefully avoiding exerting any pressure on the release valve 51. The latter must remain against the inner face of flange 140.

3rd- When the roller touches the cam 46, tighten the lock nut 136.

The cam 47 actuates together the valves 61 and 62 by means of the levers 63. The head of the valve 64 carries a screw 141 with a lock nut 142. When assembling, use is made of these screws for the adjustment as follow:

1st - Fix the cam 47 in its neutral position in using the peg 137 (figure 4).

2nd - Adjust the screws 141 until the roller of lever 63 contacts with cam 47 and the conical end is seated. This adjustment must be made without exerting any pressure on the conical end of the valve.

3rd - Tighten the lock nut 142.

(Sheet IV. Figure 6.)

In the description covering the pivoting of the yoke It has been explained that the cam 85 actuates the valve 91 by means of a lever 88. This lever is provided with a screw 143 and a lock nut 144.

The adjustment is as follows:

1st - Place the longitudinal axis EF at right angles to the axis OF, of the fork 27 in order to place the cam 85 in its neutral position.

2nd - By means of screw 143, bring the roller of lever 88 in contact with cam 85 while avoiding to exert any pressure on the push rod 90 which operates the member 92. The latter must remain against the face 166.

3rd - When the roller touches the cam 65, fasten the look nut 144.

Cam 86 acts upon valve 104 through the medium of lever 89 and push rod 103. The lever 89 is provided with a screw 145 and look nut 146.

When assembling, the adjustment of the valve is made as follows:

1st - Place the longitudinal axis EF at right angles with the training center G.H. of fork 27 in order to bring cam 86 to its neutral position.

2nd - Turn adjusting screw 145 until the roller of lever contacts with cam 86 and valve 105 is seated. No pressure must be exerted on the conical end of valve 105.

3rd - Fasten the lock nut 146.

(Sheet IX.)

The layout of the piping is shown on Sheet IX. Valve 120 is the service valve and opens or closes the compressed air supply. A manifold 148, attached to the fixed ring, serves as a liaison between the flexible pipes for the moving part of the turret and the

rigid pipes attached to the stationary part. The flexible pipes are numbered 40, 41 and 149, all other pipes are rigid.


The filling up of the various oil circuits is made by means of a pump which is supplied with the turret. See Sheets X & XII.

General Precautions, The bleeder valves mentioned hereafter must be slacked off; generally one quarter of a turn will be sufficient. Work the pump slowly in order to avoid introduction of air. Maintain a light pressure on the pump while tightening the bleeder valves.

(Sheet X.)

Place the system in neutral position, To obtain this: 1st - Make the axis of the gun coincide with the center line R.S. of the yoke.

2nd - Place cam shaft 45 in its central position and insert peg 137.

Remove the screw caps at 152 and 153 and screw emptying nipples (supplied with pump) into bleeder valves 152 and 153 and open the valves. Remove the screw caps at 154 and 155 and loosen bleeder valves 154 and 155. Connect the pump discharge with the filling valve 156 and attach the return pipes at 152 and 153. Manipulate the pump until complete disappearance of the air bubbles escaping from the pumps tank. Tighten bleeder valves 152, 153, 154 and 155, and replace screw caps. Remove peg 137 to free cam shaft 45.

NOTE. If the camshaft 45 does not rotate its full travel, a loss of oil is indicated and the system should be refilled.


(Sheet XI)

Rotating the turret, bring the pulley carriers 71 and 72 at the same level. Fully rotate the gun in either direction in order to keep open valves 61 and 62. Fill up the reservoirs 58 and 59 up to the level T.

Seal the reservoirs by means of stoppers 156. Using compressed air, slowly revolve the turret a few times in each direction in order to obtain a progressive and complete evacuation of the air from the training cylinders.

NOTE: The operations above described concern a first filling. In order to periodically refill the reservoirs, it is necessary to bring the pulley carriers 71 and 72 to the same level. Remove stoppers 156 and 157 and add oil up to the level U. Close stoppers tightly.

(Sheet XII.)

Elevate or depress the gun in order to keep the valve 104 open.

Screw the emptying nipples supplied with the pump, in bleeders 158 and 159, after having removed the plug screws.

Attach the pump's discharge pipe to the filling valve 160, also attach the return pipes at 158 and 159. Open the bleeder valves 158 and 159.

Operate the pump until air bubbles stop escaping from the pump's tank, tighten bleeder valves 156 and 159 whilst still operating the pump until the yoke tends to rise.

NOTE: The amount of oil contained in cylinders 100 end 101 to operate the jacks is ample for a long period. However, should the yoke not have full travel, a refilling is indicated as some oil has escaped.

(Sheet XII)

A locking mechanism shown in figures 16 and 17, has been provided in order to lock the turret at practically any position. Figure 16 represents the pin 163 which is part of the moving ring 21, entered in one of the holes 164 of the stationary ring 20. The turret is thus locked. To free the turret, it is necessary only to withdrew the pin 163 and to turn it 1/4 of a turn. Figure 17 shows the lock so withdrawn and so the turret can be moved. To again lock it, the pin is lifted slightly, and turned 1/4 of a turn, when the pin will enter a hole in stationery ring 20 under spring action. Figure 18 shows an arrangement for the more permanent scouring of the turret. This is intended to avoid damage to parts which might take place owing to vibrations or movement of the boat in a sea way.

This securing is obtained by means of 3 wing screws 165. To locate the tapped block on the stationary ring 20 in the position for engagement of the wing screws, a guiding mark on the moving ring must be brought in line with a guiding mark on the stationary ring.

In that position, the longitudinal axis of the gun in each turret parallel to the boat axis (Sheet VII, Figure 13. where 168 and 169 show the guns position.)

Before operating the turret, one must ensure that the pin 163 is withdrawn from its hole and the three wing screws 165 are removed.


An air leak can take place at one of the valves, one of which is shown in figure 6, sheet IV.

The leakage is generally due to some dirt which lies on the seat 167 of the inlet valve 94. To remedy unscrew plug 161, remove the inlet valve 94 and clean the faces carefully. Replace valve and spring 162.

In order to avoid oil as well as air leakage the union of the couplings should he examined periodically. The parts constituting the working components of the turret are designed to work without maintenance. Only the visible parts, submitted to friction, eliding and rolling (as cams, push rods, rollers, piston rods, etc...,) must be kept well lubricated. To refill with oil, see the notes on refilling.

Yoke will not fall when gun is depressed.
Refer to Page 5 and Sheet IV

Oil valve 105 is not opening to permit release of oil from elevating cylinders. Turn back adjusting screw 145 just sufficient to permit the yoke to fall with gun depressed, then check to ascertain



that the yoke will remain stationary with gun in neutral position, i.e. neither depressed nor elevated, Lock adjusting screw.

Turret will not train
Refer to Page 3 and Sheet II

Check air pressure and if this is within the limits given on Page 8, screw in the two adjusting screws 135 until turret turns, then check to ascertain that the air is vented through holes 53 when to guns are brought to central position. If venting does not occur, the Neoprene facing of valve 52 may have become loose or worn and the valve should be removed and replaced. Lock adjusting screws.

Replacement of training wires.
Refer to Page 4 and Sheet III

First place the movable ring 21 and pulleys 75, 77 & 79 in mid training position and proceed as follows:

To replace cable 83

Hook the ends of cable through slots in arms on pulley brackets 71 and 72 and feed cable around pulley 84. This cable cut to correct length. If, however it becomes necessary through breakage to fabricate a new one, the length should be such that it is taut when assembled.

To replace cables 69 and 70

Set the tension adjusting screws 73 to maximum loose position, then hook lower end of cable into the slotted pins at 74. Next feed the cables through the pulleys and around the movable ring 21 in the order shown on Sheet III and listed on Page 5 of instructions.



Then place the sockets at upper end of cables into recesses provided in movable ring and insert split pin to secure in place.

Tighten up adjustable screws 73 until the tension of wires is such that the wires 69 end 70 can be just brought together by using the second and third fingers in a scissor like motion.

NOTE: It will be necessary to remove the skirt pieces placed around the dome which prevent cartridge cases and links from falling into cable track before feeding cables around the movable ring.

It may also be necessary to disconnect the training cylinder assembly from the fixed ring to permit lowering of same to provide access to pulleys 80, 81 & 82. This can be readily done by removing the nuts from the three screws which secure the training cylinder assembly to the fixed ring. The clips supporting the air piping should also be removed to permit the piping to move the required amount without breaking the pipe joints.

After feeding the cables over the pulleys 80, 81 & 82, the training cylinder assembly is to be rebolted in place and after the cables have been adjusted for tension, the skirt pieces are to be reassembled.

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