| 摘要 |
711,542. Pneumatic guns. BOYLE, W. R. April 9, 1952 [April 26, 1951], No. 9827/51. Class 119 An air gun having a barrel 2 slidable to one position to open the breech and to another position for removal and replacement, e.g. by one of a different calibre, is constructed so that the barrel is engaged by an element of the single- or multistroke pump mechanism for opening the breech, The pump mechanism comprises a piston 6 sliding in the cylinder 1 under the control of a hand-lever mechanism 3, 4, the construction being such that, in the inoperative position, the links are locked over the dead-centre position by the pressure of the resilient face 11 of the piston pressing against the valve seat 9. The handle 3 is pivoted at 103 to a part of a muzzle-mounting block 39. When the piston is withdrawn, the end of the piston rod 5 engages a pin 40 attached to the barrel and slidable in a slot in the pump cylinder to withdraw the barrel a short distance and open the breech for the insertion of the bullet, the barrel being returned by hand and being locked in position by a spring 42 on the lever 4 engaging behind the pin 40. When the barrel is returned, the bullet is engaged by a pin 38 in the breech block and forced into engagement with the rifling. By disconnection of the parts of the muzzle-mounting block 39, the barrel 2 can be moved further forward and re- moved from engagement with the sleeve 18 on the breech block. The breech block comprises a member 23 containing a compressed air reservoir 7 connected by a passage 24 to the barrel and by a passage 8 to the pump cylinder. The passage 8 is closed by the end of the piston 6 when a singlestroke pump is used, or by a non-return valve 78 with a multi-stroke pump. The passage 24 is normally closed by a valve 27 under the influence of a spring 28. The lower end of the valve is a close but not airtight fit in the lower end of the reservoir, and beneath it is another valve 30 controlling passages 31. The trigger 47 is carried by a bracket 44 pivoted at 45 and normally held by a spring 48 in the position shown. The bracket carries a hammer 51 supported by a blade spring 50 and having a tooth 60 normally engaging a plate 53. Firing movement of the trigger causes the bracket 44 to swing, the tooth 60 riding on the plate 53 until it is free and then swinging under the influence of the spring 50 to strike the lower end of the valve 30, uncovering the passages 31 and allowing a certain amount of air to escape from the reservoir 7 thereby unbalancing the valve 27 and allowing compressed air to enter the barrel and discharge the bullet. The trigger is normally locked in the safety position by a lever 73 held in position by a spring 70, the trigger being released by a forward movement of the trigger finger before the firing pull. |
