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.