GB160090A - Improvements in the breech locking mechanism of guns - Google Patents

Abstract

160,090. Thompson, J. T. April 20, 1920. Machine guns.-Relates to automatic guns of the kind having a fixed barrel and a longitudinally sliding non-rotary breech-bolt, and consists in locking the bolt by a rotary ring restrained from longitudinal movement and rotated into the locking position by interengaging surfaces on the bolt and locking-ring by a torsion spring. In the construction shown, the bolt 23 is locked by a ring 37 mounted to rotate in roller bearings in the breech-body 16. The ring has recesses which in the unlocking position of the ring register with the ribs 24 on the bolt. The locking surfaces are inclined at such an angle that after the discharge the ring rotates to unlock the breech when the pressure in the barrel has fallen to a predetermined amount in accordance with the principle described in Specification 14368/14. The ring is rotated to the locking position by lugs 25 on the bolt engaging cam-surfaces 46, Fig. 13, on the ring. In a modification, a torsion spring rotates the ring to lock it. The breech may be opened by hand by means of a spindle 47, Fig. 14, mounted inside the rear part of the bolt and having a stud 48, Figs. 3 and 14, projecting through a quadrant slot 49 in the bolt into a longitudinal slot in the locking sleeve. The spindle is actuated by a handle projecting through a quadrant slot in the bolt and adapted to be connected to the spindle by a bolt 54 which is normally held in the disengaging position by a. spring. The firing- pin comprises a bell-crank lever 26 actuated when the bolt reaches its forward position.