US3029708A - Trigger mechanism for automatic firearms - Google Patents

Description

April 17, 1952 F. MARcl-nslo 3,029,708

TRIGGER MECHANISM FOR AUTOMATIC FIREARMS I Filed Feb. 15, 1961 3 Sheets-Sheet 1 "um: I'....".

April 17, 1962 F. MARCHISIO 3,029,708

TRIGGER-v MECHANISM FOR AUTOMATIC FIREARMS Filed Feb. 15, 1961 5 Sheets-Sheet 2 April 17, 1962 F, MARCHlslo TRIGGER MECHANISM FR AUTOMATIC FIREARMS Filed Feb. l5, 1961 3 Sheets-Sheet 3 "llllllllillm nuuuum assess Patented Apr. i7, i962 United Se@ Parent Ot 3,029,703 TRIGGER lit/H31(II-IANSIVI` FR AUTGMATEC 'i' .FIREARMS-v n Felice Marchisio, 70ACorsoMassimo dAzeglio, Y 'i`nrin,ltaly m l Filed Feb. l5,f19;6iSer. No. 89,539 Claims priority, application Italy Feb. 22, 196@ A2 Claims; (CL89-131).

This'invention relates to automatic firearms Suitable for selective action of Asingle orcontinuous lire,of the type provided with a trigger mechanism according to application iiled `in the U.S.A. Von the July'27, 1960 Ser. No. 45,7ll.-"

This trigger mechanism comprises namely a reciprocating breech bolt, a casing arranged'beneath the breech bolt path,a -first and a second pivot Ain said casing, a hammer capable of swinging-about said first mentioned pivot betweena recoil and a ring position over` a' path intersecting the breech bolt path, so that recoil of the breech Abolt drives Y'the Y hammer i to its recoilk position,"spring-loaded means forming together with the hammer a ltoggle link which moves the hammer to its first and second mentioned positions across a `deadmpoint position, a spring loaded delay umass adjacent the hammer on said first mentioned pivot capable of swinging about the latterl between a recoil and a :firing position 'over -a'patli intersectinglthe breech bolt path, so that recoil of the breech bolt drives the delay mass `to its recoil position; vspring-loaded lock means holding the mass in itsrecoil position,4 a cam surface on the breech bolt actin-g on' said lockmeans for unlocking the delay vmass on'return of the breech'bolt to its firing position, -alost `motion connection between `the delay mass and hammer adapted to move the latter from its recoil position through its dead point position when the by Way of example, wherein:

`FIGURE l showsthe mechanism at the limit of the recoil phase of the hammer;

FIGURE 'shows the mechanism cocked, set for single shot action; i

'FGURE 3 shows the mechanism after a single shot has been fired, and v FIGURE =4 shows the mechanism set for continuous lire action; Y :FIGURE 5 shows the mechanism set for increased rate FIGURE 6 shows an elevational view of an automatic tire arm provided with a trigger mechanism according'to this invention.` v f The-trigger mechanism is contained in a rectangular,

1 with -o'ne side plateremoved to `show theimecha'msm.

mass is near its firingposition; a Sear capable of swinging on said second mentionedfpivot from a safety to a continuous firing position'through a 4single tiring position and vice Versa, a tooth protruding `from thc'sear, a tooth radiallyprotruding from the harrnner, a two-arm beam, the arms of which-extend between the paths `ofthe said two teeth, said beam being provided with -an eyelet extending in the direction of theY ar-.ms cooperating with the second mentionedpivot, whereby the beam is moved by the tooth on the hammer acting on one of its arms to'intersectby its other arm the path of the tooth on the scar, While holdingk the hammer inl its cocked condition, and spring means acting onthe beam to displace the latter in the direction of said rst mentioned arm tocause said first mentioned arm to intersect the path of the tooth on the hammer, said tooth on the scar acting on the beam to move the latter about said second mentioned pivot to move said rst mentioned arm out of range of the tooth on the hammer. 1 I

`A triggermechanism as described above shall be briefly referred to hereafter and in the appended claims as mechanism of the type specified. This mechanism afords-a substantially reduced continuous re rate, whereby thetcrm rate` is employedto designate the number of shots which the arm is capable of tiring in aminute under antomatictcontinuous) tiring conditions; -At reduced ,continuous tiring rate` can, however, be undesirable or disadvantageous under special emergency conditions. i r

`This invention provides a fire arm provided with a trigger mechanism vof the type specified whichaffords in continuonsziire; tworates ofiire atleast, one of which is substantially slower. i

Theinventionf therefore provides a trigger mechanism of the type specified comprisingrnoreover manually controlled means acting between the hammerl and delay mass Thelother side plate 1i supports three iixed pivotsiZ, i4 and i6 thatf extend toward-thefother side-plate. v

On pivot i2, ireelyi mounted side by side, are hammer i7 and vdelay mass 18, :both having a form of a two-'arm lever. The arm 17a of the'hammer i7 andthe arm 18a of -the delay lmass u18 are provided intermediately their llength with la through hole "itil and i632, respectively, bothholes having-axes parallel'to and eqnidistant from the-axis of the pivot 12. The arm 17a-of the hammer and thearin 'lafof the delay mass normally interfere with the' recoil path of the breech bolt Ztl, the said breech bolt contains a ring pin, its rearV part 2i protriidingfrom the rear of fthe breech bolt. l The arm Ha of hammer i7 moves-fin this same planeas theiiringpin and by striking the extremity 2li of the latter cause action. The arm 18a of fthedelay mass has a semicylindrical seat-'22 housing the'head 23a of a push rod 23. The tail part of the piish rodslides in an opening 24 ofthe back plate 10a of casing l0.' A helical compression spring `25 is compressed on 'shank o-frod 23 between the plate 10a and a collar on 'rod 232 so as to pnsh'the head`23a into rseat 22. The reciprocal arrangement of seat 22, pivot IZ'and openingfZd- -f ensures that' the delay -mass i8 is continuously under action of spring-25' (through rodf23) which' tends to- `swing-the delay mass towards the breech `bolt i.e. counterclockwise yon thev drawing. f

' The arm 17a of hammer -17 carries a pin 26, which engagesa fork 27a of push rod 27. The tail end of-this rod slides in Ian opening-in theback plate lila, similarly as rodf23, anda helical compression spring 28 is compressed on the shank'of rod27 between the plate lila and a col'- laren the rod, pushing the fork 27a against pin 26t The reciprocalarrangement of pivot 12, pini zdand of the opening in the backplate lila is in this case such as to` form a* toggle link Whereas the hammer swings pin Z6 crosses'the' 'imaginary straight line joining the said opening with pivot l2. Thus, conditions being as shown in FIG. l, spring ZStends to swing the hammer 17 clockwise, while under conditions shown in FIGS. 2 to 4, hammer'17under`action of spring 28 tends to swing counterclockwise.

The *other lever arm of hammer 17 carries a lateral iinger17bv protruding into" the path of the delay mass 18. The delay mass 18 .engages the lateral nger 17b by either an abutment siirface 30y situated at the root of arm 13a or by another abutment surface 31 on the face of a tooth "18b which forms the vother lever yarm of the mass 18. Considering the conditions shown on FIG. l, the angular distance between finger 17b and abutment surface 30 relatively to pivot 12, is such, that towards the end of forward (counterclockwise) movement of delay mass 18 towards situation shown on FIG. 2, the sur-face 30 meets finger 17b and takes it across the dead centre, thus permitting the spring 28 to swing the hammer towards the extremity 21 of tiring pin. The abutment surface 31 of a tooth leb immediately adjacent to nger 17b as shown in FIG. 1, constitutes 'a stop for hammer 17 impeding any counterclockwise movement. Hence, as a system, t-he parts 17b, 30 and 31 form a lost motion connection between hammer and delay mass, the said connection becoming active in the end part of swing of the delay mass towards breech bolt 20, as described above.

With tooth 18b cooperates a pawl 32 fixed to a lever arm 33 pivoted on pivot 14, and controlled by a spring 34, which tends to bring pawl 32 on the path of tooth 18b. As shown in FIG. l, where delay mass 18 and hammer 17 are both at their extreme clockwise swing, |the pawl engages the tooth 18h, thus locking the mass 18 against a counterclockwise swing. Lever arm 33` coopcrates with Van unlocking lever 35 pivoted on pivot 12 `and projecting into the path of breech bolt 2i). rIhe latter has a cam 36, which, immediately before the end of the locking stroke (to the left on the drawing) engages the lever 35 and swings it counterclockwise. The cooperating surfaces of lever and arm 33 are such, that the above mentioned swing of lever 35 produces a counterclockwise swing of arm 33 together with pawl 32, disenga-ging the latter from tooth 18h, and thus unlocking the delay mass 18.

The trigger and sear 41 are pivoted on pivot 16. Wound around this pin is a spring 42, with one end bearing against pivot 12, the other end bearing against Itrigger 40, tending to keep the trigger in a neutral position, as shown on FIGS. 1 and 2, where the trigger bears against -a limit stop 43, xed to casing 10. The rear part of the trigger 40 forms an arm 44, cooperating with a selector 45. The selector is lformed by a pin able to rotate in supports in side plates of casing 10, and has a diametral incut 46. The selector is controlled by a wing (not shown) on the out-side of casing and can be placed in three positions corresponding to: safety, semiautomatic or single shot firing and full automatic or continuous tiring. These positions are depicted in FIGS. 1, 2 and 4, respectively. The sear 41, T Kformed, is suspended on pin 16 passing through an eyelet 47 parallel to the top bar of T; this suspension permits oscillating and sliding motions of the sear. The forearm 41a of sear 41 cooperates with a tooth 17C provided on hammer 17 `for locking it in the cocked position, i.e. immediately after the hammer passed the dead centre checked by the surface 30 and finger 17b, as shown in FIG. 2.

The body of trigger 40 houses a plunger 50 (FIG. 2) pushed against the vertical bar of the T sear under action of a compression spring, thus the sear 41 tends to slide forwards on the pin 16 and rotate suiciently to bring its front arm 41a into the path of the hammer tooth 17e. The plunger spring is weaker than the hammer spring 28, thus as shown in FIG. 2, the scar 41 is pushed backwards by the hammer tooth 17e. In these conditions, the rear arm 41b of sear 41 finds itself directly above a trigger tooth 51, and therefore the arm 41b is being raised-up when the trigger is pulled. Otherwise, when the sear is not engaged by the hammer tooth 17C, and is brought forwards by plunger 50, the arm 41h does not engage with the trigger tooth 51 (FIG. l), under certain conditions, however, described later, the sear arm 41b can be en-gaged by a step 52 (FIGS. 3 and 4) adjacent to tooth 51.

Functioning of the above described mechanism is -as follows: as usual the breech bolt is first pulled back by hand, to introduce a cartridge into the barrel. In this movement which does not differ from a recoil produced by a shot, the breech is brought back as shown in FIG. l. The delay mass 18 and hammer 17 are swung completely back (clockwise in FIG. l); and the delay mass gets locked by pawl 32. Pin 26 of hammer toggle link falls below the dead centre, and therefore the hammer tends to rotate clockwise under action of spring 28 and rod 27 and rests against a suitable limit stop (not shown).

During the successive phase, when the breech bolt moves forward, cam 36 engages unlocking lever 35, and by depressing it causes pawl 32 to free the delay mass 18, which, under action of spring 25 and rod 23 swings counterclockwise, until it is stopped against the rear face of breech bolt Z0. In the last path of its swing, the abutment surface 30 of the -delay mass 1S engages linger 17b of hammer 17 taking the latter across the dead centre of toggle link. immediately the dead centre is passed, the hammer tooth 17C engages arm 41a of sear 41; the latter recedes overcoming action of plunger 50 and comes to rest in condition shown in FIG. 2. The plunger 50 and its spring act therefore as a shock absorber for hammer 17. Now, the trigger mechanism being cocked, the further action depends on the setting of the selector 45. FIG. 1 shows the selector in safety position, where the trigger larm 44 bears against the cylindrical part of the selector, thus locking the trigger. By turning the selector clockwise by approx. 30 as shown in FIG. 2, a limited course is given to the arm 44 which penetrates into selector cut 46. It can be seen from FIG. 2, that by pulling the trigger 40, tooth 51 encounters the rear arm 41h of sear 41, and makes the said sear rotate on its pivot 16, until the hammer tooth 17C is set free land spring 28 through rod 27 swings the hammer anticlockwise against the rear extremity of firing pin 21 `located in the breech bolt 20, causing a shot to be red.

Simultaneously, sear 41 slides forward under action of the spring loaded plunger 50, thus removing the rear arm 41]? from the path of tooth 5-1. After a shot has been tired, the breech bolt recoils, repeating all cocking motions as already described with reference to FIG. 1, the only difference being that if the shooter does not release the trigger, the situation is as shown in FlG. 3. Consequently, Awhen the hammer tooth 17e` strikes against the forearm 41a, moving backwards the scar 41, its rear arm 41b slides on the step 52 and comes to rest against tooth 51 (as shown in FIG. 3) locking the hammer 17.

This invention provides means for temporarily rendering ineffective said lost motion connection.

According to @an embodiment of this invention said means comprises a pin received by said holes 101 and 102 bored both in the hammer f17 and delay mass 18, the said holes being aligned along a common axis.

The holes move on swinging on both hammer and delay mass about the pivot 12 over a slot 110 cut both through the side wall, `removed on the drawing, of the casing 2t) and wall 111 which laterally confines the body of the fire arm; the slot profile is an arc of a circle having its center on the axis of the pivot 12. The pin 10) can therefore be inserted into said holes from the outside through said slot from which it protrudes over a suitable length.

Insertion of the pin 100 into said holes connects in rotation the hammer and delay mass, thereby annulling the delay with which the hammer moves from its recoil position to its tiring position, said delay being otherwise determined by the time taken by the delay mass for moving from its recoil position to its firing position.

Adoption of the pin 169- for rendering ineffective the labove mentioned lost motion connection further affords an increment in hammering action by the hammer 17 on the striker carried by the breech bolt 20, this increment being due to the resultant action of both springs 25 and 28 which then act simultaneously to move said hammer and delay mass from recoil to firing condition.

The concomitant yaction by the springs 25 and 28 affords full efficiency of the irearm, even under unsatisfactory operating conditions 'such as are due to poor lubrication or dirt.

It will be understood that, the principle of the invention being left unaltered, embodiments and constructional details may be Widely varied with respect to the non limiting example described and shown without departing from the scope of this invention.

What I claim is:

l. In Aa tiring mechanism in an automatic rearm, a reciprocating breech bolt including a firing pin therein, a casing positioned below the path of the breech bolt, a first and ra second pivot in the casing, a hammer swinga'ble on the first pivot between a recoil condition and striking condition on a path intersecting the path of the breech bolt whereby the recoil stroke ofthe breech bolt displaces the hammer towards recoil condition of the latter, spring-loaded means jointly providing with the hammer =a toggle link causing the hammer to snap into its irst and second mentioned condition through a dead point condition, a spring-loaded delay mass swingable on the said rst pivot adjacent the hammer between a recoil condition and a firing condition on a path intersecting the path of the breech bolt whereby the recoil stroke of the breech bolt displaces the delay mass to its recoil condition, spring-loaded lock means-locking the mass in its recoil condition, a cam surfaceon the breech bolt causing the said lock meanslto unlock the mass on return of the breech to its firing condition thereby to canse the spring-loaded mass to swing into its tiring condition, a lost motion connection between the delay mass and hammer eective on the hammer to displace the latter from its recoil condition through its dead point condition as the mass is about to reach its tiring condition; a trigger swingable on the said second pivot from a safety condition to a continuous tiring condition through a single shot condition and vice-versa, `a tooth projecting from the trigger, ia tooth radially projecting from the hammer, a two-armed sear extending with its arms between the paths of the two teeth, the said sear having an eyelet therein elongated in the general direction of the arms accommodating `the said second pivot whereby the Sear is shiftableV by the tooth on the hammer acting on one of itsvarms to intersect with its opposite arm, the path of the tooth on the trigger while retaining the hammer in cocked condition, and spring means acting on lthe Sear to shift the latter in the direction of the rst mentioned arm and cause the irst mentioned arm to intersect the path of the tooth on the hammer, the said tooth on the trigger acting on the rear to swing the latter on the said second pivot thereby to bring the rirst mentioned arm out of the path No references cited.

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