US2331942A - Firing mechanism - Google Patents

Description

1943. N. K. TURNBULL ET AL 2,331,942

FIRING MECHANISM Filed Dec. 5, 1940 INVENTORS N lav-T111111. K -Tuv-nbull H ch21. 5111.1 11 QA M J W ATTORNEYS Patented Oct. 19, 1943 FIRING MECHANISM Norman K. Turnbull, Pitman, N. 1., and Herschel Smith, Southampton, Pa.

Application December 1940, Serial No. 368,652

1 Claim. (01. its-341V (Granted under the act of March 3, 1883, as

amended April 30, 19.28; .37!) 0. G. 757) The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to us of any royalty thereon.

This invention relates to automatic firearms generally, and in particular to a trigger motor synchronized with an aeroplane motor to permit firing between the blades of a propeller. of the general type shown in U. S. Patent No. 1,450,653.

The invention consists in a trigger motor for attachment to the side plate of a machine gun, said trigger motor having a plunger reciprocated by an electromagnet andreturn spring and operating in a direct line on the sear of the gun through a trip oif device, and wherein the plunger is adjustable in the direction of its motion.

It is an object of the invention to provide a trigger motor for automatic firearms that will be compact and quick and dependable in operation.

It is a further object of this invention to provide a trigger motor for automatic firearms hav ing an electromagnet plunger with adjustable position.

It is a further object of the invention to provide a trigger motor wherein the electromagnet plunger acts in a direct line on the sear.

To these and other ends, the invention consists in the construction, arrangement and combination of elements described hereinafter and pointed out in the claims forming a part of this specification.

A practical embodiment of the invention is illustrated in'the accompanying drawing wherein:

Figure 1 shows a top view in axial section of the trigger motor as mounted on the left side of a gun, and

Figure 2 is a side view.

Referring to the drawing by characters of reference there is shown a base l of the trigger motor clamped to the side plate 2 of a machine gun by means of bolt 3 the head 4 of which nests in a conical seat in the side plate. The other end of the motor is held to the side plate in a dovetail fit as at 5.

Bolted to the base I and fitted on an annular shoulder 6 of the base is a cylinder 1. This cylinder has diametrically opposite portions removed by milling as shown at 8 and $3 to an extent to penetrate the inner surface of the cylinder.

Fixed to cylinder 1 by means of screws it is a cover plate ll, and fixed centrally thereof by means of screws I2 is a washer-like retainer l3 for the spring I4.

Centrally of the cover H is a hub-like portion l5 slotted as at I 6 forming'a sleeve seat for a jacket l! of the plunger assembly.

insulation on which the coil I8 is wound consists of a disk l9 resting on the base i, another disk 29' under the cover plate I l and a cylindrical part 2! surrounding at its outer extremity the hub l5 and, at its inner extremity, an annular shoulder 22 on' the base I.

The plunger assembly consists of a central rod member 23 and jacket members i! and 24. Jacket 24 is fitted in a counterbore 2E iii-jacket i1 and each jacket has an internal bore 26 threaded to receive a threaded enlargement 21 on rod 23. Jacket 24 has a flanged head '28, knurled or polygonal and may be turned relative to jacket I! to lock rod 23 in position. For this purpose, inner jacket ll is held against rotation by means of pins 29 engaging in slots l6.

Transmission of the thrust of plunger rod 23 to the sear 39 is accomplished through the agency of a system of levers comprising a main lever 3i pivoted by a pin 32 in a slot as in the base I, and a trip cfi lever ea pivoted near the extremity of lever 3| by a pin 35.

Seated in the end of plunger rod 23 is a button headed screw 36 afiording tangential contact with face 3'5 of the lever 3| as the latter swings under urging of the plunger rod 23. This swinging is resisted by a fiat spring 38 engaging main lever 3i. Both spring 33 and coiled spring it held between retainer l3 and flange 23 on outer jacket 2t serve to hold the plunger system normally retracted when the coil is is not energized.

Trip-ofi 3 consists of a generally sectorshaped member having thin portions 22 and 43 and intermediate thickened portions J5 forming a pair of shoulders. Thin portion 82 is fitted in a slot 45 in lever 3i, and shoulders it serve to engage slant portions it on the sides of slot 45 to form a stop for the trip-ofl (it, which is urged to this position by a flat spring Al retained in the lever 3! by a screw 40.

Shown at 48 is a lead-in plug for the wire 49, and attached to the fiat portion 8 of cylinder 1 by screws 50 is a housing for the plug socket 51 consisting of a front plate 52 and side plates 53. Socket 5! is in electrical connection with coil l8 and the terminus of the coil is led out through an opening 54 in the cylinder '1 and grounded on the cylinder by means of a screw as at 55.

The wire 69 leads to an intermittent contact device functioning from an aircraft engine which is so adjusted as to energize the coil l8 only when an opening between the propeller blades is in front of the gun. Such a contact device is :old in theart and is not hereillustrated since it forms no part of the present invention. For the same reason the sear mechanism is not illustratecl, it'being sufiicient for the purposes of the present application to state that a sliding motion of the sear slide 30 will result in release of the firing pin not shown).

The provision of a. coil seated on the base of the trigger motor makes for compactness, and

The operation is as follows: Upon energization of the coil, the plunger system 23, 24 and 11 or composite plunger moves inward as a unit t compressing spring M and. forcing lever '31 inward against the pressure of spring 38. This motion is transmitted to sear slide 3l! through I trip-off 34.

Upon firing, the bolt 56 is thrown -rearWar-d-1y,

carrying with it the sear slide 30, and is then the direct linear action of the plunger on the sear slide speeds up the action. The general fidelity of operation is improved by the adjustment feature on the plunger rod. t a

We claim:

"A trigger motor for anautoniatic gun, comprising 'abase having a central Opening therein andadapted to be secured to theside plate of a gun, a cylindrical sleevesecured to said base in I coaxial relation with said central opening, a

returned to battery position, the sear slide meanwhile being returnedto its prefiring position, the

i position shown; in the t drawing. During I recoil and return of the bolt and sear, the plunger eontinues to reciprocate under the influence .of the I springs M ancl38 and the inte mittentenergization of the .0011. v I If the plunger system happens to be drawn iii- I wardly at the time therboltreturns to battery, the

cover secured to the end of the cylinder and having a hub-like central portion extending partway into said cylinder, an electromagnetic coil surrounding said cylinder, a plunger reciproeable in said hub-like portion and capable of completing amagnetic circuit to said base when said coil is energized, said plunger comprising a centrally "recessed internally threaded portion extending through the hubalike portion, an

internally threaded flanged luck nut extending into said centrally recessed portion, a threaded returned sear slide will rotate the trip-off :34

.sear slide will be waged inward to fire the next round. Thus, the gun will always fire on the stroke of the plunger next succeeding the return of the bolt to hatteryposition;

full 4 against the-pressure of its spring 41, thus permitting the bolt to return to full battery position.

On the subsequent inward thrust of the plunger,

7 trip-off 34 will have returned to position against stop 46 under the urging of spring 41 and the rod engaging the threads of the lock nut and threads of said centrally recessed portion and projecting through the central opening in the base; a centrally apertured'retainersecured to said cover for retaining the plungerin thecover, "a compression spring interposed between said retainer and lock nut flange, andvapmeans for locking the plunger against rotation in said hub like portion NORMAN K. I

HERSCHELfiMITH.

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