Patent GB-516420-A (GB)
Title: Improvements in and relating to automatic fire arms
IPC: F41A9/33
Filed: 1938-03-30
Abstract: 516,420. Machine guns. SCHEIBER, H., PETERS LOCK CO., Ltd., and PETERS, J. M. L. March 30, 1938, Nos. 26498/37 and 28355/38. [Class 92 (ii)] In order to increase the rate of fire of machine guns of the crank-and-connecting rod type particularly Vickers or Maxim guns, a spring stop is provided which limits the recoiling movement of the lock to a distance in excess of the length of the live cartridge not substantially greater than the length of recoil of the barrel, a cartridge-feed lever being also provided to feed the cartridge along the lock face while the lock is travelling said distance. The cartridge 3, Fig. 1, is extracted from the belt in the feed box by spring clips 5 carried by the lock 1, the cartridge being fed down guides 6 on the face of the lock into alignment with, the breech, as soon as the cartridge is clear of the feed box, by a transporter lever 7, pivoted at 8 in the lock, and rotated clockwise against the resistance of a spring 9 to effect this feeding movement, by the pressure of the connecting rod 13 exerted on the lever 7 through a spring buffer 12. The buffer spring may be applied to the connecting rod, or may be omitted by properly selecting the point at which the connecting rod operates the lever 7. Upward movement of the lever 7 by means of the spring 9 is limited by a stop pin 20. The gun is fired by release of the sear 18 on return of the connecting rod to alignment with the rank. An arcuate surface 21 on the lever 7, with the pivot 8 as centre, rides just below the rear cover 22 to prevent vertical displacement of the lock during recoil and return. In a modification, the transporting lever 25, Fig. 2 is pivoted at 28 on a lever 24 pivoted on the lock at 8, the lever 25 being urged clockwise, as far as is permitted by an abutment face 27 on the lever 24, by a spring 26. The lever 25 is provided with a gripper 19 for the cartridge, this gripper moving into contact with the face of the .lock and sliding downwardly thereon to eject the last-fired cartridge, in the event that the gripper has not fed a cartridge down the lock face, the empty cartridge case normally being ejected by the feeding of the following live cartridge. The transporter lever 7, Fig. 4, may be controlled by an arm 30 on the connecting rod 13, carrying a pin 31 engaging a groove 32 in the lever 7. During recoil, the angular movement of the connecting rod moves the pin 31 out of engagement with the cam groove 32, whereupon the lever 7 moves clockwise under the influence of its buffer spring (compressed by the connecting rod) to feed the cartridge down the lock face. On the return of the lock, the pin 31 engages a cam face 33 on the lever 7 and rocks the lever anti-clockwise, the pin 31 finally reentering the groove 32 to hold the transporter lever 7 locked. The buffer spring for the lever 7 may be interposed between the lever and the lock. According to a further modification the transporter lever 7, Fig. 6, is, operated by a spring controlled by an arm 39 provided with a pin 40 guided in a cam in the lock casing or barrel extension, the lever being freely mounted on the bearing of the arm 39. The arm for energising the spring operating the transporting lever may be actuated by the connecting rod, and in this case the return of the transporter lever may be effected by, an arm on the corinecting'rod as described with reference to Fig. 4. The timing of the descent of the cartridge down the lock face may be determined by horns on the transporter lever engaging a cam on the casing. In another modification, the transporter lever may have a cam face F, Fig. 11, which engages an abutment 48 on the casing, so that the movement of the lever at the point of contact with the abutment is multiplied at the point of contact with the cartridge. Resilient stops are provided to reduce the recoil of the barrel and lock and to re-impart energy to these parts on their return movement. In one form, a pair of springs 71, Fig. 13, may be provided to buffer the crank and a spring 72 may be provided to buffer the recoiling barrel. The spring stops for the crank may be adjusted to vary the position at which the crank first contacts therewith, and the spring stop for the barrel may be adjusted along the axis of the barrel to control the recoil thereof. The spring stops are carried by a detachable block hooking at 70 over the trunnion pin of the intermediate trigger lever and bearing against the rear plate of the gun casing. In a further modification, spring stop 71, Fig. 17, for the lock and a spring stop 72 for the barrel are mounted on a rack which can be vertically adjusted by a pinion controlled by a handwheel 79 to render the stops operative or inoperative, the rack being locked in either position by a spring pin 82, adapted to engage either of two semi circular recesses in the pinion. The action of the transporter lever 7, Fig. 22, and the control of the recoil of the lock may be effected by a single spring buffer 12 mounted in the transporter lever and adapted to engage a face 51 on a rear extension of the crank pivoted to the connecting rod 13, the connecting rod having an arm 30 with pin 31 engaging in a cam track in the transporter lever 7. In this modification, the pin 31 at an early stage of the recoil moves clear of the groove 32 and frees the transporter lever 7 for actuation by the face 51 on the crank, through the buffer 12, further movement of the crank after full operation of the transporter compressing the buffer spring to reduce recoil. On the return movement of the lock, the pin 31 moves along the upper surface of the cam slot in the transporter, to lift the transporter to normal position. Specifications 511,938 and 511,939 are referred to.