Victorian Institute of Engineers.
BYDRO-PNEUMATIC DISAPPEARING GUNS AND CARRIAGES AS USED IN VICTORIA.
To be read at a meeting held on September, and, 1896.
BY CAPTAIN R. HARDING, I.O.M.
N1R, PRESIDENT AND GENTLEMEN,—In my paper on " Hydro-Pneumatic Disappearing Guns and Carriages as used in Victoria," I have confined my remarks to one type. We have guns working in calibre from 5'' to 10", and in weight from 2 to 26 tons. Some idea of the machinery and structure connected With a 10" gun and carriage of this nature may be gathered from the fact that when it is moved by traversing a total weight of 86 tons is set in motion, and this Work can be done by one man. Disappearing carriages are designed to protect the guns, machinery, and the detachments working them. This is attained by Placing the whole in a pit entirely out of sight except when the gun is raised for a brief space for firing. The gun pits are built of concrete, with the necessary recesses for projectiles, lamp passages, magazines, shell-rooms, etc. The sketches of the 9.2" 8" and 6" guns (Fig. 1,) will explain the nature of this work. and give some idea of the timber, moulds, etc., necessary to make the above-menti ned recesses. The magasines, shell-rooms, etc., of course, Fare under ground, being formed in concrete in a similar manner. The method of building the pits is about the same for all natures, and for our explanation I have sketched a 9.2" 20 ton
°reach Loading Gun (Fig. 1). After making the necessary excavations, the anchor plates and 60 holding-town bolts are placed in position, and over them supported on brick in cement piers. rests the roller path, set level to the required height.. The nuts on the holding-down bolts are now screwed up to give a full nut, and set the being about e13 dia. and 10' deep. forms a is filled and surrounded a
ended with concrete to the level of the gun floor and completion of the pit: I may state that the block of concrete forming the foundation for the gun is kept separate from the walls of the pit, the block of concrete can thus move or lift, on recoil without straining the pit. Proportions of concrete are-8 to 1 being 5 of 2i metal ; 1 of screenings ; 2 of sand ; and 1 of cement. A second pit (II, Fig. 1) and a passage round the carriage is to take the recoil cylinder and give access to the fittings. The
old
sections take and holding-down n bolts.The holding-down bolts are made ofwroughtron2i"da
. and 10, long, with spherical heads and "stops" to prevent the bolts turning. as Per sketch. Weight of bolts with anchor plates, 4 tons 16 cwt. The roller path is made of cast steel in sections ; each section is carefully fitted, bolted, and keyed together. In section the roller path is similar to rough sketch " A" (Fie. 2), being the path proper for the live rollers, " F " the clip ring, " G " the rack for the traversing gear. Clips " E." fitted to the carriage, fit over the ring and engage the clip ring at the moment of firing, and thus prevent the gun from tuning over.
and are the means for putting the holding-down bolts in tension. Weight, 3 tons 10 cwt. The live roller ring (C) and live rollers (B) are now placed in position.
The live roller ring is made of Last steel, with pockets for the live rollers ; the ring is in sections, and bolted together. The live rollers are made of cast steel very carefully coned and provided with two flanges (as per sketch). Each roller LB bushed with gun metal, and is attached to the live roller ring by means of axle pins fitted with nuts and split pins, the whole weighing about 2 tons 2 cwt. The only weight on the axle pins is that of the live roller ring, the ring and pins being only required to keep the rollers equi-distant. One inner ring and one flange
2 IYDRO-PNEUMATIC DISAPPEARING GUNS & CARRIAGES IN VIC. AS
he°Ps, tl would do the work equally as well. The advantages of placing the carriage °n
live rollers in place of an acute pivot are :—First, that the shifting of the goo from the loading to the firing position does not alter the amount of work to be done in traversing ; and, second, the work of traversing is extremely light—a for of about 1`llbs. being required for each ton moved. The live roller ring is now free to move on the roller path, and is ready to receive the carriage. The lower carriage is const: ucted of mild steel plates and angles, and is held in position so as to revolve about its centre by means of the double flanged live rollers previouslY mentioned, and the front (5) and rear (3) clips I (Fig. 1), which prevents more than a trifling lift when the gun is fired. The four transoms in the lower carriage; or platform, are of the usual box girder type, but curved to suit the roller path, TO the bottom of each transom is fitted and rivetted the upper roller path (D,) (Fig.
2). beine in section similar and equal to the path portion of the roller path proper i the joints in this path " break-joint " with the joints in the four transoms forming the lower carriage, and at these points are bolted to the bottom of the transotn.
When this platform is connected it forms a circle, and is provided with sockets and footsteps for the shield pillars, and brackets for the pivot of the rocking carriage:
Two main girders span the space between the front and rear transoms ; these aye fitted over and under each transom, and securely bolted together; the whole form' ing a very solid and strong platform. Between the transoms, at each side, and the main girders there is room for the numbers (gunners) traversing and elevating the gun. Weight, 12 tons 10 cwt. The recoil cylinder (D,) (Fig. 3) is made of mild forged steel. The centre is bored out to take the ram, and is fittted at the top with a packing gland. Eleven small cylinders, 54'l dia., are bored concentric to the ram cylinder ; these contain the nec3ssary supply °f compressed air and liquid, The cylinder is fitted with a trunnion ring' and, of course, contains a number of cocks, connections, valves, pumps, etc' and with the ram weighs about 5 tons. As the recoil cylinder is the most iro"
portant part of the mechanism, I intend to return to the description of it after describing the mounting generally. The rocking carriage, or elevator (B Fig. l' A Fig. 3), consists of two cast steel beams of curved form, well fastened together wherever there is space clear of the gun by cast-steel cross transoms. At the bottom of these beams are holes bushed with gun metal for the rocking pins on which it pivots when the gun goes from the loading to the firing position °r vice versa. The top portion is formed into bearings for the gun trunnions, and are fitted with caps or cap squares. The form of the bearing is such that the thrust comes on the metal forming the beam. The cap squares are very securely fastened by means of projections, which slide into recesses formed in the beams, and are secured by means of dog-tailed pins made with a spring and keY' Lighter natures are fitted with one set-screw in each end. About the centre of the beam is fitted a cast-steel crosshead to take the recoil ram (B Fig. 3, A Fig:
4) ; the arms of this crosshead pass through bushed holes, and as it is solid it cannot be taken out of position when the beams and cross transoms of the rocking carriage are rivetted up. This part weighs about 3 tons. The overhead shield (C, Fig 1) is the next part placed in position, and it is made of mild steel about li" thick, being about 24' in diameter. This shield is made in sections, and well iffened on the underside by plate and angle beams, and is supported from the st circular platform of the lower carriage by eight pillars (G, Fig. 1) constructed of steel angle bars, each pillar being four angle bars rivetted together back to back.
In the centre of the shield there is an opening through which the gun rises' it is also provided with man-holes for the purpose of sighting, etc. All these opelting° are provided with cover-plates, which originally slipped into position from below the shield, but as they were very unsatisfactory in many ways, an did not keep out the wet, we have altered them by cutting the plates down tb' centre and jointing them up again 6' wider ; the plates are now placed on the outside of the shield and have a cover of 3" all round, and, as the shields and cover-plates have a " fall," all rain is now kept out of the gunpits, which is a great advantage to the men employed cleaning the machinery. The shield is only intended to keep out fragments of shell bursting overhead. Weight of shield and pillars, 13 tons. The gun is now mounted and completes the heavy ,gear..da is constructed of selected steel, being built up by means of a series of coils an
The r
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HYDRO-PNEUMATIC DISAPPEARING GUNS & CARRIAGES IN VIC. 3- hepps, the dimensions of the 9.2" B.L. (Breech-Loading) gun are :-
Calibre ... .... 9.2', Weight ... ... 20 tous Length of bore ... 19'-2.70•
Rifling ... ... 15 —3•47' Chamber
Total ..
Overall ... 22'-0.00"
No of grooves in rifling 38 RIFLING.
The rifling is spiral, increasing from one turn in 120 calibres at the breech to :tie turn in 30 calibres at 60.5" from the muzzle, the remainder of the twist being n1lform, viz., one turn in 30 calibres. The gun consists of the A tube around
is shrunk ew, and
the
the severalchoopsl exttend ng from rear
the breech to reception
the muzzlethe Over the breech piece is shrunk the jacket and trunnion ring. Each hoop' ié secured longitudinally by interlocking. The powder chamber is cylindrical, te,rminating in front with a curved slope. A wrought iron band for attaching the Berryin g thea shrunk over the
mechanism is secured near of the rgune by nfix ng news. g
BREECH MECHANISM.
The mechanism for closing the breech is on the interrupted screw system :011ibined with the De Bange method of obturation. The breech screw is made
I
steel, bored out to receive the axial vent bolt, etc., connected with the eee-e ghthof the circumference. The
the thread are
the gun at the longitudinally, being prepared in a similar manner, admits of the screw—when the raised portions are
b g est s breech ern and
the eighth of aurn. Thesew, when wtheawn fomhegun
t
eats c'ck can gunmetal of ethe bo a for load ing.The carrier is fitted with catches.
Which lock into recesses in the gun to hold it in either the firing or loading;
position. A Stanhope lever is fitted to the breech ring ; this is, actuated by a rachet lever provided with a reversible double pawl, the arms of which gear by means of a spring pin with the teeth of the ratchet wheel. The ratchet lever lii°ots on a fixed axis on the upper left side of the breech, and, in combination With the Stanhope lever, affords great mechanical power in turning the breech screw. To close the breech, the screw is pushed into the gun, and the locking ,ever is
tiirtted down, wne pulled
a projection or toe-piece enters taprecess The
n
in the gun, and pre-
°ents any movement of the breech screw when the gun is fired. When the breech
r
unscrewedd startedâ r f
!vewhihcauesthepofction on the lever to wedge outwards, by
face of the ß4G. Additional leverage can be obtained by applying a tube lever.
THE " DE BANGE " OBTURATOR.
The
ed in a strong canvases cover ; it with
reduced to shape proper
pressure n in a hydraulic machine, afterwards it is subjected to higher pressure in the gun by firing heavy charges. This pad is enclosed between two "protecting discs ;"
these are plates of tin, the outer angles of which are strengthened by rings of
steel, the inner part of the rear disc where it bears on the spindle, having a small:
s~ ew it pushed into the gun, ethe mubhroom head and obturator enter the chamber 48 Coned oned seat in the gun and pressed home by the tr vel bor n piitc
into of the contact
c ew.
The bore is then perfectly closed by a species of buffer in contact all round the esrenmference, while in front of it the mushroom head forms a loose end to receive he force of the gas on discharge = about 17 tons to the square inch. On firing
4 HYDRO-PNEUMATIC DISAPPEARING GUNS & CARRIAGES IN VIO.
the gun the pressure acts on the steel mushroom head, and this squeezes the pad against the breech screw causing it to expand laterally ; from symmetry of form and position this expansion must be radial to the axis and equal in every direction and experience has proved that it is sufficient tó' prevent escape of gas. The simplicity of the obturation is evident, and the system has been found perfectly effective in guns of every size. It involves little circumspection in use, and there is nothing in the gun which can ever require repair. As regards endurance the pads are almost indestructible, except perhaps from the wear of opening and closing the breech, which in time cuts the canvas covering ; spare pads are provided with every gun, and if necessary the old one can be easily changed by anyone who has seen the operation performed. Some pads have been known to last thousands of rounds, but if the firing is rapid the pad may get slightly conn pressed, when it must be led forward by means of the steel adjusting discs supplied ; or it may get softened by heat—in this case the pad should be changed and placed in cold water for a time, when it will soon be restored to good condition again. Only . field guns would be liable to each rapid fire.
FFIRING ARRANGEMENTS.
The 9.2" gun is fitted with a central firing arrangement, which is sa designed ae to prevent the gun from being fired before the breech screw is in its locked position. This consists of a steel bolt, "Axial Vent Bolt" or "Mushroom Head,' with a vent passing through its axis, and having securel to its outer end a box in which the percussion lock slides ; between this slide and the head of the bolt is a spring washer and nut ; this arrangement lessens the jar on firing. The look is pushed into position over the vent, when the breech is being closed, by a bolt gearing with a cam-groove in the breech end of the gun (the striker is not immediately over the vent sealing tube till the breech screw is locked). The lock can be lifted or lowered by hand by pulling the guide bolt out of the cam-groove- The guide bolt is attached to an extension piece ; this only on account of the large diameter of the gun (in the smaller natures the guide bolt is in the lock proper). The percussion lock as issued with the gun was most unsatisfactory and complicated, but it has been altered, and is now fairly simple and effective. The lock consists of a sliding piece containing a hammer actuated by a main' spring. It also contains a needle or striker retained in its backward position by a small spiral spring. A fork fitted with a roller and smaller fork is fitted to the top of the lock.
ACTION OF THE LociK.
A lanyard is passed through the opening in the main fork and attached to the hook on the end of the hammer ; a safety ring on the lanyard is placed on a hook fitted to the breech carrier ; the other end of the lanyard being long enough to remain in the pit when the gun is in the firing position. When the gun is ready to fire the gun captain jerks toe safety ring off and pulls the lanyard to him the hammer lifts and when in its highest position the lanyard is forced off b9 means of the small fork ; the hammer is then free to fall and strike the needle or striker which is driven forward and in its turn strikes the small piston in the head of the vent sealing tube thus firing the gun. Of course the action of the hammer is very quick, so much so, that it is impossible to see the hammer lift.
Electric firing gear was originally fitted to all guns, but at present it is not in use, RECOIL CYLINDER.
We will now return to the description of the recoil cyclinder. It will not be out of place to mention that all recoil cylinders are to pass through the Newport Locomotive shops for repair and alteration ; a work of some importance, the special tools to be made being a feature requiring great care and skill. The alter- ations are all in details ; and fittings that were originally inaccessible will be made accessible. Every joint will be faced up correctly, and all joints, except the pressure pipe joints from the air pump will be made with copper. The pressure pipe joints which are often in use, are made with square faces and joint up metal to metal. The new pattern recoil cylinder as I stated previously, is bored out from a solid ingot of mild forged steel. This method of construction is adopted to
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HYDRO PNEUMATIC DISAPPEARING DUES & CARRIA6fR8 IN VIC. 5
get rid of the uncertainty attendant upon the manufacture and employment of a castins. The cylinder rests in a cast steel trunnion ting (T., Fig. 3), the trunnions of which are supported in brackets fixed to the main girders of the platform. The centre of the cylinder is bored out for taking the recoil ram, and is fitted at the top with a packine gland. To prevent the ram from coming oat of the cylinder at the end of its stroke, it is provided with a divided piston (I and J, Fig. 4), and there is also a divided internal collar at the top end of the cylinder, the lands and grooves thus formed allow the ram to pass in or out, but when partially turned the ram is locked and prevented from coming out again. The gland for this gun is at present fitted with a cup leather and aa inner gland for packing. This inner gland was only intended to keep tight during theoperation of pumping when the pressure would not be sufficient to make the cup leather act. Experience has proved that this inner gland, at times, did all the work and the Imperial authorities state that the whole secret of packing glands for high pressures is to make the bottom of the stuffing box and the face o! the gland square. Glands are now being altered by bushing the inner glands and so making it solid, and cutting the cup-leather ring and face of gland square. Bennie's hydraulic hemp packing being used in place of the cup-leather and asbestos packing. The recoil ram is made of manganese_
bronze, and it is fitted at the top with a spring buffer. This is made up of 15 dished spring washers, and the draw bolt which connects the crosshead to the ram (B and C, Fig. 4). This arrangement allows the crosshead to be drawn off the ram about 2" against the action of the spring, if it should happen that the gun rises too violently into the firing position. The eleven air chambers (G, Fig. 3 ; B, Fig 5), which are about 5" diameter, are bored nearly to the top of the cylinders and closed at the bottom by plugs cut off flush. (These are being removed and the holes fitted with removable gun-metal plugs, to enable the cylinders to be cleaued and examined). These chambers are connected at the top by small holes and at the bottom by passages bored at an angle from a valve or air chamber ; the small chambers are thus in free communication, so that the air in each must be at the same pressure. Passages are cut from the air and valve chambers to the ram chambers (D, Fig. 5), these are fitted with four recoil valves, which permit liquid to pass from the inner or ram chamber, but not to pass back again, or, in other words non-return valves with a lift of 0.975". These valves can be reached by removing the end plugs. For the liquid to pass back again when the gun has to be raised, a bye-pass or rising valve is provided (P, Fig. 3), and this is opened by a rack and pinion moved by a rod, and hand lever. It is shut automatically as the gun rises by a chain attached to the crosshead and rocking carriage which also acts upon the rack and pinion through the rod, (S, Fig. 3). Near the middle of the cylinder on the top side, is a filling cock (N, Fig. 3), and a liquid level cock. (O, Fig. 3). An air cock (H, Fig. 4), giving a vent to the inner or ram chamber is fitted at the top of the cylinder.
This conk allows the air which finds its way into the ram chamber (every time the bye-pass valve is opened) to escape. The lowering pump (L, Fig. 3) is made of gut metal, and is a double acting force pump. The pump is fixed to the recoil cylinder. It has a constant stroke of 4in., but to obtain this under the varying positions it is thrown into by the oscillations of the recoil cylinder, it is made 2"
longer, or the amount of the oscillation. This pump transfers the liquid from the inner cylinder to the air chambers. The weight of the gun assists this action, so that the work of the pump is only to reduce the pressure under the ram till the gun can descend by its own weight. The pump is actuated by a series of levers (K, Fig. 3), the hand-lever (J, Fig. 3) being placed in a convenient position on the platform. It takes about 20 minutes to pump the gun down. The pump is the weak point in the mounting. It is really a drill attachment, and Yet its failure would put the gun out of action. To remedy this, cut-off cocks (AIM, Fig. 3) are being fitted close to the pump. It can thus be cut out and the gun remain in.
action, With the gun in the loading position all joints are subjected to hydraulic pressure. The compressed air pressure only comes on the water lever and filling cocks when the gun is in the firing position. After the gun is mounted the most important work is the charging of the recoil cylinder with the proper quantity of liquid and requisite pressure of air. The cocks and bye-pass valve are.
opened and liquid poured in to the level of the test or water level cock. This cock is now shut, and the pressure pipes from the air pump attached and pressure
6 HYDRO-PNEpä4.T,IO DISAPPEARING GUNS & CARRIAGES IN VIC..
pumped in until water appears at the air cock, which is then shut and the pump- ing continued until the firing pressure is reached (viz., 13501bs. to the square inch), and the water level cock shows a spray. If the pressure and water level is correct the gun will ;recoil when firing full charges to about 3'( from the buffers.
Firing reduced charges it only comes about f of the way down, and it will have to ne pumped down to the loading position. All disappearing guns work better when firing full charges than when firing reduced or at drill.
Lifting Pressure ... ... 1200 lbs.
Firing „ ... ... ... 1350 .,
Gun up , r,~M ... 670 ,,
Quantity of liquid .... 40 gals.
Speed of rising ... ... ... 20 seconds.
16401bs. to the square inch is the highest pressure used, viz., in 8!' guns. The action of the cylinder is (the gun being in the loading position) :—The bye-pass valve Is opened and the compressed air is free to expand and force the ram out, thus raising the gun to the firing position. The bye-pass valve is now clossd, and the liquid behind the ram has no way of return into the air chamber except through the recoil valves. When the gun is fired, the force of recoil presses back the ram, expelling the liquid through the recoil valves at such a velocity as to.
partly absorb the_recoil energy ; the remaining portion of the energy being taken up in compressing the air to its original volume.
AIR PUMP (FICA. 6).
This pump is made with four cylinders, Nos, 1, 2, 3, and 4, of different diameters, each fitted with a plunger, and placed vertically, in a tank of liquid This serves to keep them cool, and supplies the small quantity of liquid required to be drawn in with the air, to make sure that all the air is delivered at the end of each stroke. The liquid improves the gland and valve joints by keeping them moist. The arrangement of the cylinders is shown on the drawings or Fig. 6.
No I is the largest in diameter, and No. 4 the smallest. In working, the plungers of Nos. 1 and 3 are withdrawn, while the plungers of Nos. 2 and 4 are being forced into their respective cylinders and vice versa. No. 1 cylinder alone draws in a charge of air at a pressure of 1 atmosphere. The air is taken from the cup A at the side of the tank. A cock B close to the cup will allow some of the liquid from the tank to flow into the cup. A small quantity of liquid is thus drawn in by this cylinder, and when its plunger rises it delivers its charge of air to No. 2 cylinder in which the plunger is falling, and therefore the work to be done in making the stroke is distributed equally from beginning to end. No. 1 cylinder having delivered all the air will at the extreme end of the stroke deliver the small quantity of liquid which was also drawn in. This will ensure that there is no air left undelivered. In the same way No. 2 cylinder delivers its charge on the return stroke to No. 3 cylinder and the process of compression is carried a step further.
Then No. 3 cylinder delivers its charge to No. 4 cylinder, and No. 4 completes the compression up to the highest pressure required in the recoil cylinder. By these means the work to be done is more equally distributed over both the up and the down strokes, instead of being concentrated into the final portion of the stroke as it would have to be if only one cylinder were employed. When the pump is got ready for use the tank must, of course, he filled with liquid. The liquid used is a mixture of soap and water, made with soap crystals, half pound to one gallon of water. This mixture does not rust iron or steel. The liquid is poured into the pump tanks through a sieve, and should stand above the level of the tops of the pumps, so as to take up the heat which is developed in compressing the air.
To set the pump for pumping liquid the valve must be screwed up as far as it will go. • This gives an opening downwards to let away the air delivered by Nos. 1 and 2 cylinders, because the valve has been lifted off its bottom seat ; and it also closes the passage between Nos. 2 and 3 cylinders, by being screwed up against its top seat, which prevents air being sucked in by No. 3 cylinder, in place of the liquid which ought to enter by the valve J which has to be opened for the purpose.
The pump is made with folding handles so that it may take up less space.
Intakes several hours to charge a 9.2 (' cylinder and requires 8 men to work the Pump'.
Th are for t each moti secoi beve plats hand
T1 rods on tl eleva carri hrak noce by t is su Pens drut tolti the dire, The prod Pow deps clriv and mov the app: stra. rout mot desc The cart
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HYDRO-PNEl11l[ATIC DISAPPEARING GUNS & CAltRIA-GIAV IN lYIl1:
7
),
is s.
to
TRAVERSING GEAR. Fig. 1 and 2.
The rack fixed to the lower path is made of steel in short lengths. The teeth are placed vertically, so as not to get choked with dirt. The rest of the Bear used for training the gun is carried on and therefore revolves with the platform. On each side is a pinion gearing into the training rack, and driven through the third motion shaft by a spur wheel. Into this spur wheel a pinion on the second motion shaft is geared. The second motion shaft is driven from a bevel wheel and pinion contained in the box guard, on the top of the circular platform. The first motion shaft, on which the last pinion is fixed has a 3-feet hand wheel.
e ss d o.
u
1 1
ELEVATING GEAR, FIG. 7.
The elevating gear gives elevation or depression to the gun by means of two long rods (D, Fig. 1), which are pivoted at their upper ends to an elevating hoop, shrunk on the breech end of the gun, and are hinged at their lower ends to the toothed elevating arcs actuated by a train of toothed gear and hand wheels fitted to the carriage. This gear has an elevating shaft provided with an automatic regulating brake for the following reasons :—When the gun is in the firing position and it is necessary to depress it, the elevating rods (weighing about 6601bs.) have to be lifted by the elevating gear ; but if the gun has to be elevated, the weight of these arms is sufficient to make the gear run away when once put into motion. This is com- pensated for by the brake, which is made with a friction pawl which grips the drum when the gear revolves in the direction required for elevating the gun, so as tosturn the drum on its cone, and set up enough friction to more than counteract the weight of the arms. When, however, the gear is turned in the opposite direction the pawl slides freely over the drum so as to avoid turning the brake.
The springs should be adjusted to hold the drum and cone together till the friction produced is the right amount. This may be very fairly judged by making the Power required on the hand wheel for elevating the gun the same as that for depressing it. The main elevating shaft is not rigidly keyed to the cog-wheel, but is driven by a friction cone. This cone should be tightened into the wheel by the spring and the nut sufficiently to ensure that the cog-wheel does not slip round without moving the shaft under ordinary circumstances. but that it shall so slip whenever the firing of the gun jerks the shaft violently round. This frictional driving apparatus is -introduced to prevent the teeth of the wheels from being over- strained. It is of importance that the spring should be properly tightened. Every round the elevating gear slips about 3°, due to the fact that the gun recoils for a moment parallel to its axis, and at the same time it is falling due to the elevators describing an arc, so the gear must slip to allow the gun, as it were, to depress.
The 9.2" gun fires a full charge of 1641bs. of prism brown powder, made up in 4 cartridges, and a reduced charge of 821bs,
Weight of Projectile . ... 3801bs.
Muzzle velocity, full charge ... 1920 feet per second.
)1 reduced charge 1720 „
„
The gun is capable of piercing an unbacked wrought iron plate 18.8" in thickness.
In conclusion; the work of mounting 'these guns was no light undertaking considering that provision had to be made for both land and water transit ; the stores used being a fair amount of skidding and rope, two 5-ton winches, and four 20-ton hydraulic jacks. The total weight of machinery connected with the new armament being about 1000 tons, to say nothing of machine guns and the work of dismounting, moving, and again mounting the old armament, The whole of the work was carried out without accident to man or machinery.
For example, to mount a 10" 26-ton gnu at Nepean, the gun and fittings (9 tons) were forwarded to Swan Island in large mud punts.
The gun, in a case, and the large cases containing the fittings were " packed up ' and placed on skidding high enough to clear the side of the punt. The gun being stripped of its case ready to parbuckle off without loss of time. A fine day with smooth water being selected to take the punt over to Nepean—about five or six miles. At Nepean a convenient part of the beach was selected and the punt run
8
HYDRO-PNEUMATIC DISAPPEARING GUNS & CARRIAGES IN VIC.in at high tide. A bridge of skidding was quickly constructed and the gun parbuckled from the punt to the shore. Holdfasts for the winches were difficult to obtain on account of the sandy nature of the ground. The gun was then parbuckled from the bridge to tha top of the cliff ; from this point to the gun-pit is about three-quarters of a mile with several very sharp inclines. The gun was then placed ou rollers and taken some distance, but, at the pinches, it had to be parbuckled. The gun is now over 163 feet above the sea level. It was taken over
he original bank and lowered by means of jacks into the pit.
A CA D CA C R P C e ✓ n e r
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VICTORIAN INSTITUTE OF ENGINEERS.
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JDiagrams Illustrating Paper by Captain RI Harding, I.O.M.
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Discussion on Hydro-Pneumatic Guns and Carriages as used in Victoria.
Captain Harding, in reply to a question by Hr. Coane, stated that while a ship was passing from " range " to the South Channel one gun (91 2i') would be:able to fire about 15 shots at it—one every three minutes,
Mr. Turner asked if there was not danger in getting a shot at a vessel at night time.
Captain Harding said there was more danger to the vessel, as it was very risky travelling through the heads at night time ; it was a very awkward place to come through. It was quite a frequent occurrence to see a vessel in the Rip stationary with her engines going full speed ahead.
Mr. Turner would like to offer a little tribute of thanks to Captain Harding for the very able description of the guns he gave at the School the other evening. He had no doubt that it was a very great satisfaction to them to know that this part of the coast was protected by arms of such precision and power, and that they were in charge of an officer of such personal characteristics as Captain Harding.
He would would quote words that had been used on another occasion. and say : Were he a youngster again he would be proud to serve under him." The military part of our defences was, perhaps, the most interesting and important. If it could be arranged, he thought a visit to the forts at the Heads would be, indeed, profit- able and instructive.
Mr. Fyire said that this subject was a little beyond the ordinary mechanica engineer. 21,752,050ft lbs. of work were performed in Y26 sec. Length of gun 15*ft. 1920 = Th of one sec. ;. 21,752,050 X 126 550 = 4,983,300, roughly 5,0)0,000 H.Y. This would take a 10 H.P. engine about 66 min. to perform the same amount of work.
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