Patent GB-578621-A (GB)
Title: Improvements in or relating to ordnance
IPC: F41A9/42
Filed: 1942-04-13
Abstract: 578,621. Loading ordnance. MOLINS, D. W., HARVEY, V. P., MASON, J. A., POWELL, G. F. W., and MOLINS MACHINE CO., Ltd. April 13, 1942, No. 4865. [Classes 9 (i), 92 (i) and 92 (ii)] Relates to semi-automatic ordnance of the kind having a swinging loading tray and a wedge breech-block moved automatically to closed position on the insertion of a round. According to the invention, means are provided to set the fuze of a round in the loading tray and means are arranged automatically to actuate the fuzesetting means and the loading tray in timed relationship so that the fuze is already set when the tray is in loading position. Further, a rammer device, operatively controlled in timed relationship with the tray, automatically rams the round into the breech, the gun being automatically fired when the breech is closed. The timing is such that there is provided an automatic fuze setting-loading- firing cycle giving a substantially constant " dead-time " for each round. The invention is shown in Figs. 1 and 2 accompanying the Provisional Specification and in Fig. 29 of the drawings accompanying the Complete Specification applied to a 3.7" semi-automatic anti-aircraft gun 2 in which a horizontally-sliding wedge breech-block is opened on run-out of the barrel and closed automatically by the release of the extractor arms when a round is rammed home from a swinging loading-tray 4. The object of the improvements is to render automatic and sequential the following operations : (1) moving a round from a receiver 18 on, to the loading-tray 4 when this occupies the receiving position shown in dotted lines in Fig. 29; (2) moving the fuze-setting head 8 up to the fuze-cap of the round in the loading-tray, setting the fuze and withdrawing the head as described in Specification 578,330 ; (3) swing- ing the loading-tray about axis AA, Fig. 1, into line with the open breech as shown in full lines in Fig. 29; (4) sliding a rammer in the loading-tray to load the round, thus partly releasing the breech-block to retain the round (5) reversing the rammer ; (6) returning the loading tray to the receiving position which releases the breech interlock thus permitting full closure of the breech-block accompanied by automatic firing of the gun as described in Specification 578,629. To render the " dead time " as constant as possible, the complete cycle of operations is accomplished in a predetermined time, say 3 seconds. Electric motors FSM, TM, RM drive the fuze-setter, tray and rammer respectively and by means of a contact drum connected to the shafts of the motors, these are brought into operation in sequence at the correct time after the first motor is started ; the main switch being opened at the end of a predetermined time, say 3¢ secs., by a spring motor or on the completion of a cycle. Referring to the complete circuit diagram, Fig. 2, when a round is placed on the receiver, the cycle starting push CSP is closed by hand, the fuze-setting motor FSM starts and a cam on the motor shaft tilts the round from the receiver on to the loading-tray where the fuze is set, whereupon the rotary switch RS driven by the motor FSM stops said motor. Just as motor FSM stops, a timing-switch FSTS is closed momentarily energizing relay TFCR which is maintained over its contacts RHC and, at contacts CCRC completes the circuit of contactor TMC which upon closing starts the tray motor TM. This motor operates to swing the tray through the agency of a resilient crank and connecting-rod 6, one half rotation of the crank moving the tray forward into loading position and the other half rotation returning the tray to receiving position. When the tray reaches the loading position, switch TCS opens and de-energizes relay TFCR and hence also the contactor TMC, thus stopping the motor TM. Also the rammer contact switch RCS is closed, energizing relays ShFR and CR in series. The relay ShFR energizes the shunt field of the rammer RM for forward movement of the rammer and the closure of the lower contact CRC maintains the circuit over limit switch RLS and also energizes contactor RC to cause motor RM to advance the rammer. At the end of inward movement of the rammer, limit switch RLS opens, deenergizing CR and RC, thus CRC moves to upper contacts and energizes the withdrawal contactor WC as the limit switch WLS' is now closed. During the change-over of contacts CRC, the shunt field is maintained as the relay ShFR has a delayed opening. With WC energized, the motor RM runs backwards and finally opens WLS, whereupon the motor RM is braked to rest by the short-circuit resistor BR, its field being maintained by the delayed opening of the relay ShFR. The rammer slides in the loading tray under the action of a cable gear passing over a drum 10 driven by the motor RM through a flexible shaft 11. The cables pass over pulleys 9, 8, there being a ramming cable and a withdraw cable and the pulleys 9 being adjustable for tightening the cables which can be rearranged for hand ramming. During the ramming stroke, switch TRS is closed, energizing the relay TRCR which is maintained at its contacts RHC. When the gun breech - block has moved sufficiently to retain the round, interlock switch BIS is closed, thereby completing the circuit prepared by contacts CCRC of relay TRCR for contactor TMC, whereupon the tray motor TM returns tray to receiving position and by momentarily open TCS de-energizes relay TRCR and contactor TMC. When current from battery B flows to the various motors, coil COSW of cut-out ISCO slowly pulls its core downwards against a time-lag escapement TLE. After, say, 3¢ seconds, the core breaks a toggle TJ and opens a main switch COC. Normally, a cycle of operations is complete in 3¢ secs. and the core then returns to its uppermost position. On an overload, coil ShWRC closes its contacts and coil COShW aids coil COSW to pull down the core quickly so that switch COC opens immediately. The fuzesetter FS is controlled, through a flexible shaft 17 in accordance with the predictor readings on a receiver dial, either by a hand follow-the-pointer drive 13 or from a remote point by an oil servomotor unit 14, the drive being through a chain 15 and a variable-speed gear for fuze-setter corrections. The gun is fired by a handle or automatically by a pressure device, only after the cocking-lever has returned to inoperative position by the use of the device described in Specification 578,629. Specifications 125,442, [Class 9 (i)], and 578,333 also are referred to.