GB803028A - Improvements in or relating to air-guns - Google Patents

Abstract

803,028. Air guns. MAYER & GRAMMELSPACHER DIANAWERKE. March 20, 1956 No. 8654/56. Class 119 In a spring operated air-gun air is compressed by at least one of two pistons 1 and 2 which are coupled together by a control device to equalize their speed of travel. Embodiments in which the control device is either a rack and pinion gear or meshed gear sectors are described, but bell cranks or scissors-type linkages, sprockets and chains, and the like may be used instead. The opposed pistons 1 and 2 carry sealing members 5 and can slide in a fixed cylinder 3 where the compression space between them 3a communicates through a small hole 3b with the barrel 4. The space 3a may be continuous (Fig. 5) or it may be divided into two by a partition 3c with communicating holes 3b (Fig. 3). The partition 3c has frictional bearings between it and the cylinder walls and a stud 3d locates it so that it cannot rotate, but is capable of small axial movement when it is contacted by two pads 5 of the pistons. Rack 1a and 2a depend from the pistons 1 and 2 through longitudinal slots in the underside of the ends of the cylinder 3 remote from the spac 3a. The racks engage either side of a pinion 6 (Fig. 2) in a fixed housing 6b and are retained there by smooth rollers 6c pressing against their backs. A longitudinal bar 9 is linked at 9a- 10a with a cocking lever 8 and carries on a projection at its back end a breech closing pin 12. The front conical face of the pin 12 co-operates with a washer 4a to seal the breech. and it has an extension 12a to locate a projectile 13 in the bore forward of the role 3b. The bar 9 has a shoulder which contacts the rack 2b so that when the cocking lever 8 is rotated in a downward direction about its pivot 8a, the linkage 9a-10a causes the bar 9 to move back and open the breech and also moves back the rack 2b. The rack 2b turns the pinion 6 so that the rack 1a also moves and the pistons 1 and 2 travel apart against their springs 7. They are held apart by a bent 2c on the rack 2a which releasably engages a spring loaded trigger 11. The return movement of the bar 9 leaves the mechanism @ocked ready to fire but a lever 11a on the trigger pivot co-operates with a catch 9c on the projection on the bar 9 to prevent the trigger from being released before the breech is closed. In the embodiment in Fig. 5 the control mechanism comprises levels 5 and 5a pivoted at 5b and intermeshed at 5c Rollers on the far end of the levers engage behind opposed pistons 1 and 2 and a spring 7 between the other ends of the levers takes the place of the two cylinder springs of Fig. 3. A pivoted cocking lever 8 is linked to the lever 5a and carries a breech block 8c with an air channel 8d between the bore and the space 3a. The trigger 11 engages with a bent 5e in the lever 5 to retain the mechanism in the cocked position and a safety device 12 co-operates with an extension of the cocking lever 8 and with a hand operated safety latch 13. In an embodiment in Fig. 6 (not shown) the mechanism is generally similar to that in Fig. 3 but the partition 3c is fixed in the cylinder 3 and only the front half of the space 3a communicates with the bore of the gun. In this instance the rear piston 2 has no sealing member and does not compress any air when released, but only acts as a countermass to balance the backward movement of the piston 1.