To Dismount and to Assemble Parts of the Gun and Carriage.
To dismantle and to assemble the breech mechanism.—Grasp the operating lever and open the breech; when the block is open, force the block latch out of its seat in the block by gently pressing it into its seat in the carrier. Take hold of the block and revolve it to the left until it stops; then pull it to the rear, taking care not to drop it. The block latch can now be readily removed. After the firing-lock case has been removed the operating lever can be removed by forcing its pivot up from beneath by a gentle pressure from the palm of the hand. The lever latch can be removed by pressing in on the latch at a point near its lower end opposite its pivot; a hole in the latch is cut eccentric with reference to the pivot and a shoulder on the pivot prevents their displacement until the latch is forced in and the hole is concentric with the pivot. When this occurs, the pivot can be readily pulled out and the latch removed. To remove the block carrier force the hinge pin up by hand until it can be caught by the head, and by swinging the carrier back and forth, if the pin sticks, it can readily be removed, taking care not to drop the extractor lever. The extractor can now be removed from the gun.
To dismantle and to assemble the firing-lock case and mechanism.—Take hold of the milled headed locking bolt situated at the lower end of the firing-lock case, pull it to the rear; at the same time revolve the firing-lock case upward about 45° and pull it gently to the rear. This will remove the case with the firing mechanism complete from the gun. Press the trigger-shaft detent until it disengages from the notch in the firing-lock case. This will allow the trigger shaft with its detent, to be withdrawn. Then gently press on the front end of the firing pin, forcing it back into the casing. This will allow the trigger fork to fall out. Then, with one finger placed on the front end of the sear, force it outward; at the same time grasp the front end of the firing pin, which is roughened for the purpose. Give it a sharp pull. This will remove the firing-pin spring and sleeve from the casing. Then place the front end of the firing pin against a block of wood, bear down on the firing-spring sleeve until the spring is compressed sufficiently to disengage the slot in the rear end of the sleeve from the small lug on the rear end of the firing pin; slightly turn the sleeve, and then the sleeve can be separated from the spring and pin. By an unscrewing motion the spring can be removed from the pin. The sear can be removed by gently pressing it in toward the center of the casing.
To assemble, reverse these operations, taking care before driving too hard on the end of the trigger shaft that the square hole in the trigger fork is in position to receive the tapered end of the trigger shaft. No tools are required for assembling or dismantling this mechanism.
To remove the recoil indicator.—The ends of the clips of the recoil-indicator guide are bent down to form stops to hold the indicator in place. To remove the indicator, these parts are opened up sufficiently to permit sliding the indicator out of the guide. When the indicator is assembled, these clips should always be closed down to prevent its loss.
To dismount the gun.—Elevate the muzzle slightly. Remove the recoil indicator throw, unscrew the cylinder-end stud nut, and shove the gun to the rear until the clips are free from the guides. As the gun slides off the cradle, it must be properly supported. For this purpose, from 6 to 8 men working in pairs with lifting bars are required.
To mount the gun.—Depress the muzzle slightly. Shove the piece from the rear over the cradle guides with the clips engaging the guides. Assemble the cylinder-end stud nut, taking care that the locking stud on the recoil lug enters one of the recesses provided for it in the end of the cylinder. Assemble the recoil indicator throw. The dust guard should be assembled with the gun.
In moving the gun on or off of the cradle particular care must be taken to support the breech end so that the gun clips remain in line with the gun slides. The firing shaft is also quite liable to injury during this operation, and care should be taken to prevent its being struck by the nozzle of the gun or by implements in the hands of the cannoneers. The cradle should be placed at the desired elevation and azimuth before beginning either of these operations and not changed during its progress, since the working of either the elevating or traversing mechanisms when the gun is only part way in battery brings an excessive and unnecessary strain and wear upon those parts.
To dismount the cylinder.—Bring the gun to approximately zero degrees elevation; unscrew the cylinder-end stud nut and the piston-rod nut; remove the cradle head, front. The cylinder is now free and may be pulled out to the front.
To assemble the cylinder in the cradle.—The counter-recoil springs and the retaining ring being in assembled position, shove the cylinder (turned so that the drain plug in cylinder head comes on top) into its seat from the front, with the projecting stud on the recoil lug of the gun entering one of the recesses provided for it in the cylinder end; assemble the cradle head; screw in place the piston-rod nut and cylinder-end stud nut.
Be sure that the projecting stud on the gun enters one of the holes for it in the cylinder end before screwing the cylinder-end stud nut up all the way.
To assemble the parts of cylinder after cleaning.—The parts should be reassembled immediately after cleaning and inspection, and the cylinder filled with hydroline oil issued for that purpose. The piston should be moved back and forth in the cylinder by hand to make sure that all parts are correctly assembled and are without interference. The cylinder should then be assembled in the cradle and the gun pulled from battery by hand and permitted to counter recoil rapidly to insure that all parts are in proper position for firing. This should never be done, however, unless the cylinder is known to be filled with oil. In reassembling the parts the condition of the vulcanized-fibre washers between cylinder head and cylinder, and between cylinder-end stud and cylinder end should be noted; they should be replaced whenever necessary to prevent leakage. In removing and inserting the piston rod care should be taken to keep it central in the cylinder, so as not to bind, burr, or spring any parts. The dismounting and reassembling of the parts of the cylinder should in every case be supervised by a commissioned officer. Before firing an inspection should be made to ascertain that the different parts, especially the piston rod and the cylinder-end stud nuts, are correctly assembled.
To pack the stuffing box.—The stuffing box is packed with five rings of Garlock’s hydraulic waterproof packing, 0.25 inch square. The packing is issued cut into rings of such size that the ends meet around the piston rod. The latter being assembled, each ring, placed so as to break joints with the preceding one, is forced in succession into its seat by a packing tool of copper or hard wood, one end of which is shaped like a carpenter’s gouge and the other end forms a handle strong enough to stand light taps from a hammer. Such a tool may be readily improvised by one of the battery mechanics. After the five rings are firmly seated in the box, screw the gland down on the packing.
In assembling the glands be sure that at least four of its threads are engaged with the threads of the cylinder head; otherwise the threads of the gland may be stripped in firing. With new packing it may be found difficult to insert more than four rings and secure sufficient engagement of the gland. In such a case the box should be packed with four rings and the piece fired a few rounds, after which the fifth ring should be inserted.
Adjustment of the gland.—The adjustment of the gland will require the exercise of some judgment. If screwed up too tight, the frictional resistance of the packing on the piston rod will be increased so much that the counter-recoil springs may fail to return the gun to battery, especially at high angles of elevation. It should be screwed up just tight enough to prevent the leakage of oil through the stuffing box. Ordinarily this can be done by hand, but in cases where hand power is not sufficient the wrench provided for the purpose should be used. When its proper adjustment is determined, the gland should be lashed with copper wire to prevent it from screwing up or unscrewing.
To remove the piston rod.—Unscrew the gland sufficiently to release the pressure of the packing upon the rod; unscrew and remove the cylinder head. The rod may then be withdrawn from the cylinder. In dismounting and assembling the cylinder head (and also the cylinder-end stud), the cylinder should be held from turning by a spanner applied to the head retainer or flange on the front end of the cylinder. It should never he clamped in a vise, as its walls are thin and not intended to withstand such usage.
To remove the counter-recoil buffer.—Remove the cylinder-end stud screw; unscrew and remove the cylinder-end stud; the counter-recoil buffer is attached to the latter.
To dismount the springs.—Bring the gun to approximately zero degrees elevation; unscrew the cylinder-end stud nut and the piston-rod nut; shove the gun about 1 inch from the battery; attach the sleeve end of the spring compressor to the cylinder-end stud and put sufficient strain on the compressor to relieve the retaining ring from spring pressure; then remove retaining ring (and cradle head) by loosening and swinging aside the retaining-ring bolts; ease off slowly on the spring compressor until the springs are free.
To assemble the double counter-recoil springs.—With the cradle at maximum elevation and the trail horizontal, place one outer and one inner spring in the cradle until the front ends are about 2 inches in; set up a separator against the forward end of these sections and enter the second outer and inner springs, keeping the separator upheld between the sections; similarly when the outer end of the second section is 2 inches inside the cradle set up the second separator; place the third outer and inner sections on the recoil cylinder. Screw the spring centering tool onto the cylinder-end stud, the small end pointing rearward; pass the sleeve end of the spring compressor through the gun lug and the inner springs and attach it to the cylinder-end stud. Enter the rear end of the cylinder in the spring at the front end of the cradle and push the cylinder back until the springs are at free height, keeping the spring compressor taut. Attach the block and fall carried in the battery wagon to the spade of the carriage or to some improvised support and connect it to the spring compressor; put sufficient strain on the spring compressor to bring the spring column to its assembled height.
As the spring column approaches its assembled height the spring support must be turned so that its guide lugs properly enter in the spring-support guide grooves in the cradle; assemble the retaining ring, disconnect the spring compressor and the spring centering tool from the cylinder-end stud; push the gun back into battery and assemble the cylinder-end stud nut. When the retaining ring is assembled the nuts for the retaining ring bolts should be screwed up until they just come into contact with the retaining ring. If these nuts are screwed up too tight they will deform the retaining ring, with the result that it becomes difficult to assemble and dismount the cradle head. A wrench is provided for turning the spring support to its proper position.
To assemble the single counter recoil spring.—The same method is followed except that no separators are used. The spring compressor is provided with a second eye at its large end which may be used in case the sleeve end should become broken; in case this end is used, however, it will be necessary to pass the compressor through the cradle from front to rear, through the gun lug. For disconnecting the compressor the method used is identical to that previously described.
The cylinder-end stud nut should never be removed when the gun is at an elevation, and the gun should not be elevated when the cylinder-end stud nut is not in place. To prevent the cylinder-end stud from rotating a screw for the cylinder end is provided. This screw for the cylinder end must be removed before attempting to unscrew the cylinder-end stud.
Since the springs are assembled under an initial load of over 750 pounds, a pull of more than 750 pounds must be exerted upon the spring compressor in assembling them. This can be done by passing a handspike through the loop at the rear end of the compressor and making use of the service of the entire gun squad, or the block and tackle may be used as described above. To avoid the possibility of injury to the gun squad in compressing or releasing the springs, all should be required to keep arms and bodies away from the front of the spring column during these operations.