Patent GB-1504312-A (GB)
Title: Shock absorber for an automatic weapon
IPC: F41A25/02
Filed: 1975-02-26
Abstract: 1504312 Shock absorbers INTERNATIONAL VIBRATION ENG 26 Feb 1975 [27 Feb 1974 17 Sept 1974] 8129/75 Headings F2E and F2S [Also in Division F3] The specification discloses a number of different embodiments of a shock absorber for use with an automatic weapon firing in bursts, such as is mounted on an aircraft, all the shots in a burst except the first being fired during the return movement after recoil of the weapon: the device comprises a recoiling member 1 receiving or constituting a part of the weapon and axially slidable in a cylindrical support member 2 fixed to the aircraft-elastic restoring means act between the member 2 and the member 1 and braking means (hydraulic or frictional) act between the members 1, 2 during recoil movement but are arranged to have their effect reduced or removed during recoil movements produced by all shots of a burst except the first. In the embodiment of Figs. 1-4, the member 2 forms with a peripheral sleeve 3 an annular chamber 4 and with the member 1 an annular chamber 12 divided into rear and front variable volume chambers 33, 34 and within chamber 12 is provided an annular sliding piston 28 cooperable with seats 25, 27. The chambers 4, 12 are filled with oil and non-return valves 15, 17, 19, 22 are provided for communication between these chambers during operation of the weapon. When a first shot of a burst is fired the recoiling member 1 moves rearwards in the direction of recoil R from its initial position shown in Fig. 1. This causes decrease of volume and increase of pressure within chamber 33 until valve 15 opens to connect chamber 33 with chamber 4, from whence fluid opens valve 22 to connect chamber 4 with chamber 34. In this way, hydraulic damping or braking is obtained throughout recoil. When the recoiling member 1 reaches its extreme position the restoring means move it in a direction opposite to arrow R but piston 28 under the action of a weak spring 32 only moves forward slowly and becomes disengaged from seat 27 so that chambers 33, 34 are directly connected. At this stage the second shot of the burst is fired to interrupt the return of the recoiling member 1-the recoiling member 1 moves rearwards again but with reduced force and due to the interconnection of chambers 33, 34 no braking occurs. This continues throughout the burst but after the final shot the piston 28 will be engaged by seat 25 and chamber 34 will be sealed to raise the pressure therein until valves 34, 17 are opened to interconnect chambers 33, 34. When the recoiling member 1 has returned to its initial position piston 28 moves under the influence of spring 32 to its initial position shown in Fig. 1. In the modification of Fig. 5 (not shown) the piston (28) is supported against a front seat (35) which divides chamber 34 into two parts and has two diametrically opposed non-return valves (37, 38) to control circulation between the two parts whereby some braking occurs during the burst. In the embodiment of Figs. 6-8 friction members 112 are provided within an annular bush 111, and these members 112 provide braking on a moving element 118 during recoil movement after the first shot of a burst is fired, rearward movement of the members 112 being limited by a stud 113 engaging a stop 170 on fixed member 101, the element 118 being moved by a stop 119 of recoiling member 102. During the return movement a second shot is fired before a stop 120 on member 102 begins to move element 118 and hence no braking occurs. After the final shot is fired the stop 120 will move element 118 on its forward return movement and a restoring member in emplacement 103 is compressed and then relaxes. In a modification hydraulic braking means are associated with element 118. In the embodiment of Fig. 9 (not shown) the stop (120) is replaced by a ring (121) and a rectangular spring (125). In the embodiment of Figs. 10-14 two return springs 126, 127 act as restoring means between the recoiling member 102 and the support member 101. A moving element 128 has a stop 139 co-operable with a stop 138 on member 102 and a head 132 attached to sliding bush 131. The bush 131 has an inner ledge 135 which abuts against an elastic ring 136 partly located in a groove 137 of member 102. When the first shot of a burst is fired, member 102 recoils compressing springs 126, 127, bush 131 being driven by ring 126, and at this stage a second shot is fired. At the end of the burst the members return to their positions illustrated in Fig. 10.