THE CARRIAGE.
For the purpose of description, the carriage is considered as composed of the following groups: Sleigh (including recoil mechanism), cradle, trail, traveling lock, elevating mechanism, traversing mechanism, wheels, road brake, and shield.
The sleigh contains the recoil and counter-recoil mechanism and serves as a support for the howitzer, being secured to it by the breech key and the holding-down band. The recoil counter-recoil cylinders, and two air cylinders are bored in the sleigh and form the recoil mechanism. The ends of the recoil and counter-recoil cylinders are attached to the cradle and when the howitzer is fired the sleigh and howitzer recoil, sliding on the cradle sides.
The holding down band is anchored on either side to the front band clips, which are secured to the sleigh. Grooves are cut underneath the two top edges of the sleigh, and are lined with bronze liners, known as sleigh slides. These liners slide on the cradle clips and guide the howitzer during recoil. Five longitudinal cylinders are bored in the sleigh, the two upper cylinders running about one-third the length of the sleigh, forming air tanks and are closed at the front end by the air tank heads. The left air tank head is provided with an opening in which the gage-cock body is assembled. A pressure gage may be assembled through an adapter to this gage-cock for ascertaining the pressure in the counter recoil system. The gage-cock is also provided with a pointer which registers the quantity of liquid in the system on a scale provided on the air tank head. The two lower cylinders extending the full length of the sleigh, form a housing for the recoil mechanism, the right cylinder being the counter-recoil cylinder and the left the recoil cylinder. The small equalizing cylinder in the center of the sleigh, extending only a short distance, is closed at the front end with the filling valve, through which air or liquid is introduced into the system.
155 MM HOWITZER, MODEL OF 1918 (SCHNEIDER)
SECTION, IN BATTERY
The counter recoil cylinder is connected by a passage to the right air tank and also to the small equalizing cylinder, the latter being connected to the left air cylinder, thus maintaining equal pressure in both air cylinders and in the counter-recoil cylinder. The counter-recoil cylinder is closed at the rear end with the counter-recoil cylinder head and at the front end with the stuffing box, through which the counter-recoil rod and its piston moves. The recoil cylinder is closed at the rear end with the recoil cylinder head and at the front end with the recoil cylinder stuffing box, through which the recoil piston rod operates. This rod is hollow and serves as a buffer chamber for the buffer rod, which is securely screwed to the recoil cylinder head at one end, the other end carrying the counter-recoil valve. The recoil and counter-recoil rods are fitted with the piston rod nuts on the front end which engage the piston rod lock plate.
The cradle is a steel U-shaped plate reinforced by several transoms and supported by the trunnion bracket, elevating segment brackets, and in traveling position by the cradle band which engages the clips on which the howitzer recoils when in action. The sleigh traveling locks are mounted at the extreme ends of the cradle and used to lock the sleigh to cradle when the howitzer is in traveling position.
The cradle is mounted on trunnions on the carriage, and by means of elevating segments geared with the elevating mechanism may be inclined at various firing angles. When carriage is traveling the rear end of the cradle rests on the cradle traveling lock, thereby relieving the elevating mechanism of the weight of the howitzer, sleigh and cradle.
The left trunnion of the cradle is bored out to receive the sight and bracket. The shoulder guard is located on left side of the cradle just back of the trunnion bracket and protects the gunner from the recoiling parts. The firing mechanism is located on the right side of the cradle and provided with a safety device which prevents the piece from being fired when the piston rod nuts are not engaged by piston lock.
The recoil indicator is located just back of the trunnion bracket on the right side of the cradle and consists of a steel spring which is adjusted by means of a nut so that the pointer bears against a scale engraved on the edge of the sleigh indicating the length of recoil. The front end of the cradle is covered by the cradle head and provided with an opening through which the pressure-gauge adapter may be assembled to the gauge-cock body. The lower half of the front end of the cradle is closed by the front transom, forming a guide for the piston-rod lock which is operated by means of a lever. When this lever is lowered the lock plate moves to the right, releasing the piston-rod nuts. When the lever is raised the lock moves to the left, locking the nuts in firing position. The locking device is protected by the cradle front cover which holds the lever in firing position when closed. The filling valve is accessible through the cradle bottom cover located on the bottom of the cradle to the rear of the front transom. The pump bracket is located on the left side of the cradle near the front.
155 MM HOWITZER, MODEL OF 1918 (SCHNEIDER)
LEFT SIDE ELEVATION, IN BATTERY
155 MM HOWITZER, MODEL OF 1918 (SCHNEIDER)
ELEVATING MECHANISM
Recoil and Counter-Recoil Mechanisms. When the howitzer is fired the recoil mechanism exercises its retarding influence by means of a liquid which is obliged to pass through an orifice whose size diminishes as the movement proceeds, thus checking the recoiling mass. The recoiling movement of the gun actuates at the same time the counter-recoil mechanism, which acts on the counter-recoil liquid and forces it into two reservoirs, thus further compressing a gas therein contained. When the recoil movement is ended the expansion of gas forces the counter-recoil mechanism back “into battery,” and the recoil cylinder again exercises its retarding influence to prevent a too rapid return and shock. The normal recoil is 51.375 inches (1.305 meters).
When the piece is fired the howitzer and sleigh move to the rear, the recoil and counter-recoil rods, which are held by the piston-rod lock remaining stationary. The liquid in the counter-recoil cylinder is thus forced into the air cylinders, building up a pressure sufficient to return the howitzer to battery. The liquid in the recoil cylinder is forced through the orifices in the recoil piston rod and then through the throttling ring. The tapered buffer rod, which is attached to the recoil cylinder head, moves through the throttling ring, gradually closing the orifice, thus keeping the pressure constant as the velocity of recoil is reduced. As the buffer rod moves to the rear the counter-recoil valve is opened, allowing the liquid to pass freely into the buffer chamber. As the gun returns to battery the buffer valve closes, forcing the liquid to pass through the small clearance around the valve, thus absorbing the energy of counter recoil.
By means of the elevating mechanism the howitzer, sleigh and cradle are inclined at the various firing angles, varying from zero to 42 degrees, by rotation in the trunnions of the cradle.
Two elevating segments attached to the cradle are actuated by the elevating pinion shaft operating in bearings integral with the elevating worm wheel case secured to trail. To lower end of worm shaft is fitted a worm which engages a worm wheel and pinion shaft in the gear case. On upper end of worm shaft is attached the elevating hand wheel fitted with a handle and plunger enabling the operator to lock the howitzer at any desired elevation. The motion of the handwheel is transmitted through the worm gear to the pinion shaft and thence to the elevating segments.
155 MM HOWITZER, MODEL OF 1918 (SCHNEIDER)
TRAVERSING ROLLERS
The handwheel is provided with a handle of a spring locking type, downward pressure on which unlocks it from the handwheel latch plate, permitting the mechanism to be operated.
Traversing Mechanism. The traverse of the carriage is obtained by means of the traversing mechanism causing the carriage to slide on the axle, the trail pivoting on the spade. The movement is 3 degrees each side of center or a total of 105 mils.
At the center of the axle is rigidly attached a bronze traversing nut through which passes the traversing screw which may be operated from either side of the carriage by means of handwheels connected to the screw through bevel gears and shaft. The traversing screw operates in the travelling housing longitudinally and held in position by thrust bearings and thrust bearing adjusters at both ends of the screw. When either of the handwheels is operated the traversing screw is rotated and moves to the right or left as the case may be, carrying the entire carriage which moves across the axle on traversing rollers.
In order to reduce friction during the traversing operation the carriage rests on the axle through Belleville springs and two concave faced traversing rollers mounted on roller shafts in the axle housing. When gun is fired the Belleville springs are compressed and the carriage rests on the axle through the bronze traversing roller boxes.
On top of axle projecting to the left of carriage is riveted an azimuth scale graduated in mils so that the position of the carriage on the axle may easily be seen at any time. When in traveling position the carriage should be locked to the axles by the axle traveling lock, thus relieving the traversing mechanism from unnecessary stress.
155 MM HOWITZER, MODEL OF 1918 (SCHNEIDER)
TRAVERSING MECHANISM
The axle traveling lock is a device employed to relieve the traversing mechanism from unnecessary stress when the carriage is in traveling position. When the carriage is prepared for traveling the traveling lock engages a series of square grooves cut in the center of the axle. The lock is operated by an eccentric on the end of the traveling lock shaft which is controlled by the lock lever fixed on outer end. The lock lever may be placed in two positions marked “to travel” and “to fire,” by means of its handle which is provided with a spring plunger engaging the traveling lock catch. In order to properly lock the carriage in traveling position it is necessary to traverse the carriage to the center position on the axle, thus permitting the locking device to engage the grooves cut in the center of the axle.
The air pump is furnished for the purpose of charging and maintaining the necessary pressure in the counter recoil reservoirs. When in operation it is attached to a bracket on the carriage by means of a screw clamp and connected to the reservoir by the filling pipe. The pump will operate against a pressure of 400 to 600 pounds per square inch.
The liquid pump is a single-acting-plunger used for charging the counter-recoil system and for the purpose of replenishing losses of liquid from the cylinders. Power is applied through a hand lever connected by parallel links and a cross-beam at the lower end of the piston. The hand lever is detachable and also used in connection with the air pump. When in operation the pump is attached to a bracket on the carriage by means of a screw clamp. The filling pipe is employed to connect the liquid pump with the recuperator cylinder.
The reservoir for compressed gas is a commercial seamless cylinder with a capacity of 2,842 cubic inches and is charged with nitrogen gas at a working pressure of 2,000 pounds per square inch (140 kilograms per square centimeter). The reservoir is provided with a needle valve and a connection for the pressure gage or filling pipe. This cylinder is used for charging the counter-recoil system and may be carried on the artillery supply truck furnished with 155-mm organizations.
155 MM HOWITZER, MODEL OF 1918 (SCHNEIDER)
AIR AND LIQUID PUMPS
155 MM HOWITZER, MODEL OF 1918 (SCHNEIDER)
TRAVELING POSITION
The filling pipe is used to connect the counter-recoil reservoirs with the air or liquid pump or with the compressed gas reservoir.
Pressure Gage. The gage for the compressed gas reservoir is calibrated from 0 to 150 kilograms per square centimeter. It is used to ascertain the pressure of gas in the reservoir and must be attached before screwing on the filling pipe. The gage for the pressure-gage adapter is calibrated from 0 to 60 kilograms per square centimeter, is screwed into the side of the adapter and used to test the pressure in the counter-recoil system.
The quadrant sight, model of 1918 (Schneider), is mounted on the left trunnion of the carriage, both in traveling and in action, and should not be removed by the battery mechanics. The principal features of the quadrant sight are: The cross-leveling mechanism, the elevating mechanism, and the angle of site mechanism.
The cross-leveling mechanism principally consists of the leveling worm, leveling stop, antibacklash spring, leveling clamp, and cross levels. By means of the cross-leveling mechanism the quadrant sight is adjusted to proper alignment with the bore of the howitzer.
The bracket fits into the trunnion on the left side of the carriage and is provided with four tennons which engage slots in the face of the trunnions keeping the sight in proper alignment with the bore of the howitzer. The bracket is screwed in place by the bracket bolt; the front end of the body of the quadrant sight fits into the cylindrical part of the bracket and is held in place longitudinally by four lugs.
QUADRANT SIGHT, MODEL OF 1918.
(SCHNEIDER)
The body of the sight is rotated by the leveling worm engaging the worm segment cut on the under side of the body. The outer end of the worm is provided with a knurled hand wheel by means of which the leveling mechanism is operated. The leveling stop, secured to bracket, engages slot in the body, thus limiting the angular motion of the body in either direction. The rear end of the cylindrical part of the bracket is split and provided with a leveling clamp by means of which the body may be locked in position after it has been leveled.
The cross level is located on the rear edge of the sight shank and serves the gunner in determining the level position of the instrument. The level vial is a glass tube, closed at both ends, and partially filled with a liquid consisting of 4 per cent alcohol and 60 per cent ether, a small bubble remaining in the tube. Graduations are etched on the circumference of the tube to indicate the central position of the bubble. The vial is held in a level-vial tube, the ends being wrapped in paper and set in plaster of paris. The knurled cross-level cover fits over the holder and, together with the level-vial tube, are held in place by the cross-level caps, which close the ends of the holder. When closed, the cover serves as a protection for the vial.
The elevating mechanism consists principally of a sight shank, elevating worm wheel, antibacklash pinion, elevating worm, elevating worm eccentric, elevating scale drum, and scale drum housing.