| 摘要 |
998,607. Air guns and projectiles therefor. ENGINEERING DEVELOPMENTS Ltd. May 2, 1962 [May 3, 1961], No. 16906/62. Headings F3A and F3C. An air gun comprises a chamber 45 in which air is impressed by means of a piston 46 moved forwardly under the action of a spring 62, the bore 24 of the barrel 16 being connected to the chamber 45 by means of a passage 138 containing a check valve 142 adapted to prevent air compressed in the chamber 45 from acting on a projectile carried on the barrel until the pressure in the chamber 45 has reached a predetermined value which opens the valve 142. The valve 142 includes a spring 148 located between a ball valve 146 and a plug 150 threadably mounted in a tapped portion 152 of the passage 138 for adjustment of the valve. The projectile 110, Fig. 2, is provided with a bore 116 which receives a pair of spaced propellant caps 120, 121 of nitrocellulose ignitable under the effects of heat and pressure. The arrangement is such that on opening of the valve 142, the pressure and temperature of the gas is such as to ignite the propellant caps and cause a pressure differential which closes the valve so that substantially all the energy developed by the ignition is used in propelling the projectile. The gun has a dropdown barrel pivoted at 20 and provided with a locking mechanism comprising a spring-urged latch pin 31 adapted to engage a fixed pin 36, the mechanism being released by means of a transversely extending pin 38. Cocking levers 92, 94 pivoted at 96 move the piston 46 to the cocked position when the barrel is pivoted about the pin 20. |
