CARRIAGE.
Weights and Dimensions.
| Weight complete | 1642 lbs. |
| Weight of gun and carriage complete | 2657 lbs. |
| Weight at end of trail, carriage limbered | 114 lbs. |
| Diameter of wheels | 52.5 in. |
| Length of recoil | (about) 45 in. |
| Maximum angle of elevation | (338 mils.) 19 degrees |
| Maximum angle of depression | (178 mils.) 10 degrees |
| Amount of traverse of gun on carriage | (106 mils.) 6 degrees |
The gun is of the built-up type and consists of a forged steel tube which extends from muzzle to breech. A breech hoop is shrunk over the rear of the tube and extends beyond it to provide a breech recess. This recess is threaded with seven threads to take the breechblock. A bronze jacket encircles the central portion of the tube. Inner and outer locking hoops screw to and firmly fasten the tube, hoop and jacket together and prevent them from separating under the stresses of recoil. A muzzle hoop is screwed on the tube at the end of the muzzle.
75 M.M. FIELD GUN
MODEL OF 1897 (FRENCH)
75 M.M. FIELD GUN
MODEL OF 1897
(FRENCH)
A recoil lug on the under side of the breech hoop forms a point of attachment between gun and recoil mechanism through the media of a piston rod and coupling key.
The rear sight is attached to the rear portion of the breech hoop. On top of the hoop at its rear end are two quadrant seat plugs. The front sight is fixed on top of the rear end of the jacket. A sweeper plate which sweeps and lubricates the roller is secured to the front end of the jacket.
The breechblock is the Nordenfeld rotating type, cylindrical with seven threads which serve to screw it into the rear of the breech. The breech is opened and closed by rotating the block 120 degrees around its axis. The block advances during the rotation due to the pitch of its threads and forces the cartridge case into the bore. The gun cannot be fired until the block has been completely closed, a condition which must exist before the striker of the firing mechanism is in line with the primer cartridge of the projectile.
The extractor consists of three parts:
1. Two arms connected by a hollow shaft.
2. A spindle which passes through the shaft and fastens it to the breech.
3. An extractor tang.
The action of the extractor is as follows: When the breech is closed the arms of the extractor are pressed against the face of the tube by the rim of the cartridge case which bears against them. The extractor tang projects into a groove in the inner face of the breechblock known as the loading groove. This groove is circular and its depth is equal to the projection of the extractor tang. It terminates in a helical guide surface called the “ejecting ramp.”
75 M.M. FIELD GUN
MODEL OF 1897
(FRENCH)
The first part of the movement of opening the breech serves to move the grooves in front of the extractor tang. This pressure forces the extractor tang back into its slot in the breech hoop and as the extractor tang is firmly seated in the extractor, the arms of the latter are rotated around the extractor spindle. The arms being brought to the rear, press against the rim of the cartridge case, which is thereby started and ejected.
Inversely (the breech being open) when a cartridge case is smartly inserted in the chamber the rim carries the arms of the extractor forward. The extractor tang is thereby forced against the beveled surface of the ejecting ramp and automatically starts the closing movement of the breechblock.
A safety catch is provided to keep the breech locked between the time that the breech is closed and the shot is fired.
The firing mechanism consists of a striker or firing pin seated in the breechblock, a firing hammer, firing rack, spring and lanyard. By pulling the lanyard the hammer is drawn back and the rack moves forward against the compression of the spring due to its being geared to the hammer. When the lanyard is released, the spring forces the rack back which in turn causes the hammer to fly forward and strike the primer. A safety device is provided for locking the hammer while the piece is in the traveling position.