US2531121A

US2531121A - Mechanical time fuse

Info

Publication number: US2531121A
Application number: US557285A
Authority: US
Inventors: Fink Jean
Original assignee: George W Borg Corp
Current assignee: George W Borg Corp
Priority date: 1944-10-05
Filing date: 1944-10-05
Publication date: 1950-11-21
Anticipated expiration: 1967-11-21

Description

Nov. 21, 1950 J. FlNK 2,531,121

MECHANICAL TIME FUSE Filed 001:. s, 1944 s Sheets-Sheet 1 Fig.1

IN V EN TOR.

JEAN FlNK BY ATT/Y.

Nov. 21, 1950 J. FINK 2,531,121

MECHANICAL TIME FUSE Filed Oct. 5, 1944 5 Sheets-Sheet 2 INVENTOR. J EAN F l N K ATT Y.

Nov. 21, 1950 J. FINK 2,531,121

MECHANICAL TIME FUSE Filed Oct. 5, 1944 5 Sheets-Sheet s INVENTOR. JEAN PINK BY Wm ATT'Y.

Nov. 21, 1950 J. FlNK 2,531,121

MECHANICAL TIME FUSE Filed Oct. '5, 1944 5 Sheets-Sheet 4 INVENTOR. J EA N Fl N K ATTY.

Nov. 21, 1950 J. PINK 2,531,121

MECHANICAL TIME. FUSE Filed Oct. 5, 1944. 5 Sheets-Sheet 5 INVENTOR. J EAN F I N K 146 MMA,

Patented Nov. 21, 1950 MECHANICAL TIME FUSE Jean Fink, Delavan, Wis, assignor to The George W. Borg Corporation, Chicago, 111., a corporation of Delaware Application October 5, 1944, Serial No. 557,285

Claims. 1

The present invention relates in general to mechanical time fuses for projectiles and the object of the invention is to provide a new and im proved fuse of this character.

. A special feature of the invention is a mechanical time fuse provided with means whereby the detonator may be exploded by point impact as well as by timing mechanism. In View of this feature, the invention maybe referred to as a combination time and point impact fuse.

Another feature involves the provision of both spring power means and centrifugal power means to operate the timing mechanism. The spring power means supplies sufficient power to run the timing mechanism when the fuse has a low rotational speed and the centrifugal power means supplies the additional power which is required to overcome the increased friction when the fuse has a high rotational speed. The fuse is adapted for use in shells which have a low rotational speed, therefore, as well as in shells such as antiaircraft shells which have'a relatively high rotational speed.

The foregoing and other features, including new and improved safety devices for arming-the fuse, will be described fully hereinafter, reference being had to the accompanying drawings, in which- Fig. l is a view of the new fuse complete with the body or base which screws into the shell, the lower or setting cap, the upper cap or nose of the fuse, and the timing mechanism. The timing mechanism is shown in elevation and the other parts are shown in section;

Fig. 2 is a top view of the timing mechanism, or fuse proper; 1

Fig. 3 is a bottom view of the same;

Fig. 4 is a section through the timing mechanism on the line 44, Fig. 5;

Fig. 5 may be regarded as a horizontal section taken along the dividing line between plates I! and H3, Fig. 5, and shows certain parts as they appear when looking down on plate [1;

Fig. 6 is a view similar to Fig. 5, but looking down on plate I 2. A part of plate I3 is also shown;

Fig. 7 is a View of the fuse block Hi as seen from below, with the driving .mechanism and firing pin release mechanism;

Fig. 8 shows the interior of the setting cap and the means for couplingthe setting cap to the base of the fuse;

Fig. 9 is a plan View of plate l9, showing the 22, 23 and 24, shown in Fig. 3, and are clamped;

Referring to the drawings, the timing mecha-. nism or fuse proper may conveniently be described first. The parts are supported by a frame; comprising a so-called fuse block l9, which may;

be an aluminum die casting, and a stack of circular brass plates II to 2|, inclusive. These plates are properly located relative to each otherand to the block ill by means of three dowel pins to the block I H by two machine screws and 26.

There are in addition tWo

screws

21 and 28 for. holding the plates together as a unit to enable? the plates to be assembled independent of the.

the bottom plate The main shaft of the timing mechanism is a.

dicated at 33, Fig. 4, and has two bearings, one in. the block I3 and the other in the plate 9. At its lower end and just above the plate l9 the shaft.

carries the gear wheel 3|, which is the first wheel of the gear train. Above the gear wheel 3| is the pinion 32, formed integrally with the shaft. The

shaft 30 is hollow and contains a pin or rod 33 which forms part of the point impact firing. mechanism, as will be described shortly.

The shaft 30 is driven in part by means of two.

weights

34 and 35 which move-outward by cen trifugal force when the shellcontaining the fuse is fired and rotate the shaft by means of two,

toothed sectors

36 and 31 which are inengagement with the pinion 32.

which are pivoted on the pinsupported .between the block I0 and plate 2|. 39 carries the integrally formed toothed sector 36. The weight 34 and the

links

38 and 39 are located in a deep recess 4| in block l9, which provides space for rotation of weight 34 in a clock:

wise direction about pin 40 as seen in Fig. '7. The

sector 36 overlaps the margin of the recess 4| and extends into a shallow recess 4|. The arrangement of the other weight 35 and associated parts is the same as described in con-j nection with weight 34. The two weights engage the main shaft 30 when the timing mecha-l nisrn is fully wound, and the shaft accordinglyfunctions as a positive winding stop. In Fig. 7.

the parts are shown in fully wound position.

The power is also supplied to the shaft 30 by. means of the two helical springs I13 and which surround the pins 4|] and 40', respectively; on which the supporting links for the weights 3i and 35 are pivoted. As shown c1ear1y in the case Referring to Figs. '7 and 4, the weight 34 is a short section of brass rod and is rigidly secured to two links38 and 39 The lower link of spring I'll, one end of the spring rests against the wall of recess 4| in the block In while the other end of the spring bears against the weight 35. The other spring H is arranged the same way. These springs are tensioned when the fuse is wound and are quite stiff. They supply sufiicient power to drive the timing mechanism when the shell in which the fuse is used has a'low rotational speed such as 2000 R. P. M., for example, being assisted by the driving

weights

34 and 35 which, however, do not supply much power at such a low rotational speed. In shells having higher rotational speeds the weights are more effective and supply an increasing amount of power which is approximately in proportion to the increase in friction which is manifested at such higher speeds.

The gear train is of known construction, but

i will be described briefly. The gears and associated .pinions are locatedin openings or recesses in the plates and are supported on arbor's which have bearings in the plates. The general arrangement will be understood .from Fig. 4, which shows how gear 44 and its associated pinion are supported on an arbor which has hearings in plates 18 and H.

The first wheel of the gear train is the gear S LmOunted on shaft 30, as already mentioned. The gear 3! meshes with the pinion which is associated with gear 42. The gears 42, '43 and M are the second, third and fourth wheels of the gear train, respectively, and are shown in Fig. 5. The fifth wheel 45 indicated by dotted lines and drives "the escape wheel "46, which can be seenin'Fig. 6.

The escape wheel is mounted on an arbor whichihas bearings in plates H and It, as shown in li ig. 4, and drives the oscillatable pallet arm 41 by means of the two ,Ipallets "48 and 49 formed integrally therewith. The pallet arm'is mounted on a member '50 which has pivots formed at its opposite ends whichhave bearings in plates H and IA. The melnberEO'has a transverse .perforati'on through which the 'hairspring extends and in which it is fixed by a wedge. The endsof the hairspring are located in slots cut in downwardly extendingprojections on the two nuts or blocks 52 and 53 which are slidable in recesses cut in plate H. The "nuts '52 and 53 may be moved along these recesses in'either direction by means of the adjusting screws 54 and ""55 to adjustthe effective length of the hairspring and "thus regulate the rate of the timing mechanism. g

The gear train is normally locked by "two dogs or detents 63 and '64, Figs. '4 and 6,'whichengage the "teeth o'fithe escape wheel at. .These detents are located ina recess in plate H and are pivoted on the pin65. A spring '66, supported on spring retainer .51, presses the two detents 1'63 and "64 against the escape wheel. The spring retainer is also supported on the pin "55*b'ut is prevented from rotatingbyreason of the fact'that'its outer rounded fend lies in a recess in plate F2. The spring "66 does not actually bear against the detents63 :and B4 but against the two weights with which the detents are providedwhich are effective to operate :the detents to release the escapefwheel when the fuse is rotated.

Fig. 6"al's0 shows thestarting lever 8|. Fuses such as disclosed herein are self-starting, but occasionally one is encountered which will fail to start if the pallet .arm happens to he in 'a particular'po'sition relative to the escape wheel. The provision of "the starting lever avoids any possibility of trouble due to starting failure. The starting lever 8| is pivoted on a pin or stud 82 which is fixed in plates l and 12. The lever has a headed sleeve 83 similar to a tubular rivet which is provided to give an increased length of bearing surface on the pin. The lever is located in a recess in plate l3, this plate being partly shown in Fig. 6. The -'next plate above, plate [4, has a similar recess or cut-out to provide room for the member 83 and for the enlarged head of pin 85. The pin 85 is located at the end of lever 8| and extends downward past the pallet arm 41. The lever and. pin can be seen also in Fig. 3. A spring 84, Fig. 6, bears nular recess in plate 3 which surrounds the hole for screw '25 and is held in position by said screw and plate I4. i

The starting lever operates by centrifugal force'when the shell containing the fuse is fired and rotates in a clockwise direction as seen in Fig. 6 until it engages "the edge of the cut-out in plate l3. During this -m-ovement the pin slides along the edge of the pallet arm 41 and givesit a flip which insures starting 'of the timing mechanism. The lever is locked in operated position by spring 84, which bears against the side of the lever instead of the end thereof shortly'before the lever becomes fully operated.

'The locking means for the escape wheel and the starting lever are so related that a higher rotational speed is required for operation of the starting lever than is required for operation of the locking means "to unlock the escape wheel. This result is attained by proper proportion'ing of the parts and by regulating the tension in

springs

66 and 84, and insures that-the escape wheel will be unlocked when the starting lever operates. Another reason for the lower operating speed for the locking means "is that the detents are maintained in operated (unlocked) position 'by centrifugal force and must remain in operated position throughout the flight of the shell, including the end "portion of the flight during which the rotational speed falls ofi considerably.

The primary function of the timing mechanism isto release "the 'firingpin and -fir'e the shell at the expiration of "a predetermined time. The arrangement by which this is'acco mplishe d will now be described.

The firing pin is shown in Fig. 4, where it is indicated by the reference character 55. It-comprises a short lower rod section and an upper cylindrical section which is slidable in a bore in block In. The cylindrical portion of the firing pin .is hollow and contains a helical spring 51. When the firing 'pin is cooked, as it is shown in Fig. 4, the "spring 51 is compressed between the firing pin and the end of the bore in block Ill. The firing pin is held in cocked'position by the engagement of the shoulder at the bottom of the cylindrical section with the centrifugally operated locking member 59 which is mounted on a short heavy shaft 69 having hearings in the block [9 and in plate 19. Fig. 7 shows clearly how the member 59 extends beneath the shoulder on the firing pin to hold it in "cocked position. The shoulder is slightly inclined as shown in Fig. 4 to enable it to slip off member 59 easily when the latter is rotated.

The locking member '59 is itself "normally lo ked by a cam 51 on shaft 62. This shaft extends through the block and has bearings in the block and in plate IS. The cam BI is formed by cutting away the shaft on one side, as shown in Fig. 7, where the shaft passes the member 59. At the other end the shaft is provided with a lever I0, Fig. 2, secured to the shaft in any suitable manner. 'The lever 19 has a weight II at one end whereby the lever is adapted to rotate shaft 62 when the weight moves outwardly by centrifugal force. The lever and weight are located in suitable recesses formed in the block [0, as shown in Fig. 2.

Movement of lever 10 and rotation of shaft 62 are normally prevented by means of a so-called safety disc 12 on the main shaft 3!]. This disc has an arm 13 which is in the path of a projection 15 on the lever 19, when the fuse is in unset condition, as shown in Fig. 2. There is also a timing disc 14 on the main shaft which prevents movement of lever It after the fuse is set and until the timing mechanism has measured off the time interval determined by the setting operation.- The construction and arrangement of these parts can be explained in con nection with Fig. 4.

There is a flanged sleeve 16 which has a press fit on the shaft 30, the shaft being knurled where the sleeve is attached in order to avoid any chance of the sleeve rotating relative to the shaft. The safety disc 12 is assembled on sleeve 16 next to the flange and has a downwardly projecting ear 1'! which enters a peripheral slot in the flange and prevents rotation of the safety disc relative to the sleeve 16 and shaft 30. The sleeve and safety disc are thus fixed on the main shaftand rotate with it. The timing disc '34 is assembled on .the sleeve 16 above the safety disc M, there being a washer interposed between the two discs, and is held in place by means of a conical spring washer 18 and a ring 19. The end of sleeve 16 is expanded by a spinning operation to secure the ring 9. The timing disc 14 .is thus frictionally secured to the main shaft 30, and may be rotated independent of the shaft in order to set the fuse.

The end of shaft 30 which projects above the sleeve 16 and ring 19 is threaded and carries a nut 80 which is screwed down tight against the end of the sleeve 16. The fuse may be wound by applying a wrench to the nut and rotating the shaft.

When the fuse is wound the gear train runs in a reverse direction. The detents S3 and 64 lock the escape wheel 46 against backward as well as forward rotation and accordingly they must be disengaged from the escape wheel before the fuse can be wound. For hand winding this is accomplished by means of a tool having two tapered pins which enter the holes 8" and 88, Fig. 3, and force the detents away from the escape wheel. The starting lever 8|, which otherwise would interfere with the oscillation of the pallet arm, is assembled in operated position and is only moved to its normal position after the fuse is regulated. In this connection it will be noted that the lever is accessible through an opening in plate H, as shown in Fig. 3.

When the fuse is fully wound the tool for disengaging the locking detents from the escape wheel is removed while the winding power is on in order to permit the detents to engage the escape wheel and prevent the gear train from run-- ning down. Or, if more convenient, the pallet arm may be held until the tool can be removed.

The member 59 is not only locked by the cam 6| as described but is positively held against rotation by means of a so-called set-back pin Ill, Figs. 3 and 7. Fig. 3 shows one end of the pin, which is located in a passage formed by aligned holes in plates H to 9, inclusive. The pin proiects through plate F9 for a distance about equal to the thickness of member 59 and this projecting portion being engaged by member 58, the latter is prevented from rotating, even if it is released by cam 6!. Fig. '7 shows the projecting portion of pin i l l in section so that its location relative to member 59 may be understood. Set-back pins such as described have been used before in other fuses and accordingly no further explanation will be required.

The detonator is a brass capsule 9!] which contains an explosive and is threaded into a passage formed by aligned holes in plates l i to I5 inclusive. The slotted and perforated end of the capsule 83 can be seen in Fig. 3. It is behind the plane on which the sectional view Fig. 4 is taken and in this figure is indicated by dotted lines.

The arrangement for firing the detonator may be explained in connection with Figs. 4 and '5. There is a fairly stiff flat firing spring 9i which is secured to plate H by two screws and which extends to the left beneath the pin 33 and the firing pin 56, as shown in Fig. 4. Recesses are provided in plates l'l, i 5 and 59 to accommodate the spring 8i. At a point about midway between the pin 23 and firing pin 56 the spring 91 is provided with an offset prong 94, the point of which lies in a slot 93 in plate it just above the detonator 9D. This slot may be seen in Fig. 5. It will be clear from the foregoing that spring Bi may be depressed by either the firing pin 56 or by pin 33, which is part of the point impact firing mechanism, to cause the prong 9 3 to strike the detonator and explode it.

Operation of spring. 9! to fire the detonator is normally blocked by a safety device which includes the lever 95 and weight 96. The safety lever 95 rests on plate [6 and is located in a recess milled out on the under side of plate H. The shape of this recess is indicated by a dotted line in Fig. 5. The lever is pivoted on the pin 91 which is supported by plate it below the lever and by plates l1 and it above. The recess for lever 95 also contains a spring 98, one end of which presses against the lever 85. The other end of the spring has an abutment against the side of hole 99, which is drilled through plate I? only, to intersect the recess and eliminate the rounded corner that would otherwise be present to invite creeping of the spring.

As will be seen from Figs. 4 and 5 the weight 96 is located squarely beneath the firing spring 95 and since the lever 95 rests .on plate H5 and bridges the recess in this plate which is beneath spring 95 the spring is positively blocked against operation by either the firing pin 56 or pin 33. The lever 95 is operated by centrifugal force acting on weight 96 when the shell containing the fuse is fired and rotates on the pivot pin 9! in a clockwise direction. The rotation of the lever enablesthe weight 95 to move out from under the firing spring 9| and arm the fuse. The lever is locked in operated position by the spring 88, the end of which drops into a notch at the end of the lever.

While the safety lever95 is operated by centrifugal force as explained, its operation does not take place immediately after-the shell is fired, but isdelayed for one-half second (or other desired interval) by the timing mechanism. As can be seen from Fig. 5, the rotation of lever 95 is nor mally prevented by the shaft WI which is engaged by the end of the lever. At its lower end the shaft ill! is of reduced diameter and has a bearing in plate I5. The shaft extends upward through the plates above plate I and through block H], where it has another bearing. At the upper end of the shaft the operating lever I03 is secured, said lever being located in 'a recess in block IB. The end of lever I83 extends beneath the safety disc Hand is bent at a right angle toform a hook Hi5 which engages an oppositely formed hook Iii l at the edge of the safety disc. Thus the lever I93 is normaily locked and cannot rotate shaft H but when it is released by the safety disc, the lever moves under the influence of centrifugal force and rotates shaft It"! in a clockwise direction, as seen in F igsz and5. The shaft IGI is cut away at I62 where it passes the safety lever 95, as shown in Fig. 5, whereby such rotation is effective to release the lever.

The various recessesor cutouts in the plates which are required for mounting .of the parts tend to unbalance thefuse and in order to prevent such unbalance other cutouts are made which would not be otherwise required. This is illustrated in Fig. 9., which shows plate l9, having recesses ll 2, 1 l3 and m, which are provided to balance the fuse. Plate 29 has a recess corresponding to recess H4, while plates to [8, inclusive, have recesses corresponding to recesses H2and H3.

This substantially completes the description of the timing mechanism, so-called herein to distinguish it from the complete fuse, which includes the base, setting cap and. upper cap or nose. The timing mechanism assembly as shown in Fig. 4 is generally referred to as a fuse, since it includes a considerable number of parts in ad-- dition to those which are actually included in the timing mechanism. There are a few points involved in the assembly and regulation of the fuse, meaning the fuse as shown in Fig. 4, which it was not convenient to discuss before and which may be dealt with at this time.

The helical spring 51 in the firing pin is very stiff and consequently theifiring pin has to be assembled in the block If! by means of a suitable fixture provided for this purpose and adapted to. supply Sufficient power to force the firing pin into the block and compress the spring. After the firing pin has been cocked in this manner the screw I I0 is inserted and the block is removed from "the fixture. The screw H0 is'threaded into a tapped hole in the side of block if) and has an unthreaded part at the end which enters a slot in the firing pin to hold it in place. After the block has been assembled to the rest of the fuse the screw I I0 is removed and the firing pin is held in cocked position by the locking member 59, as previously described. 7

Before it is assembled to the base the fuse must be regulated and since the rotation of the fuse affects its rate the fuse is timed while it is being rotated to simulate its rotation during the flight of the shell in which it is to be'used. The spinning of the fuse for regulating purposes of course results in the operation of the timing mechanism, which in turn brings about the release of the safety lever 95 by the safety disc 72, and the release of the locking member 59 by the timing disc 14.

As regards "the safety lever 95 it may be 'explained that the lever is reset by turning the fuse on its side and by 'introducing a suitable tool in the 'hole "I -ill], 'Fig. 5. "This hole extends through plates ll to '11, inclusive, and can be seen also inFig. 3. The tool may be a rod with a wedge shaped end which can be passed into hole [0i] farenough so that the end is beyond the spring and then rotated. As soon as the spring 98 is compressed enough so that the end of the spring clears the notch in the lever the weight 96 will drop into position beneath the firing spring 91 by gravity.

When the locking member 59 is released by the timing disc it remains held by the set-back pin HI and does not release the firing pin. This saves the time that would otherwise be required for cooking the firing pin after each run of the fuse during the regulating operation. However, the firing pin release must be tested and to do this the set-back pin is :movedby hand to setback position and the fuse is .run again. After this run the firing pin will have to be cocked, as-

suming that it was released properly, which is accomplished by means of a cocking device which includes means for holding the fuse and a rod adapted to'enter the hole I I5 and to which power may be applied to restore the firing pinto cocked position.

The reference character H6, Fig. 3, indlcate the sloping end of a slot which is milled in the edge of plate I3 to provide a light passage used in timing the fuse during the rate regulating operation. Timing apparatus in which such a light passage is used is disclosed in the application of Thomas B. Gibbs, Serial No. 385,629, filed March 24, 1941, now Patent No. 2,360,653.

After-the fuse has been tested and regulated it is ready for assembly to the base H20, Fig. l. The fuse is properly oriented on the base by means of a locating pin r23, fiXedto-the base and shown in 'Fig. 10, which enters the hole 124, Fig. 3. The fuse is clamped to the base bymeans'of a flanged ring 126 and a threaded sleeve I27, as shown clearly in Fig. 1. The ring 126 is made very slightly shorter than the fuse, to insure a slight clearance :between the lower flange on the ring and the base. Theupper flange is stepped, that is, it comprises'inner'and outer flanges, of which the outer fiangeengages the block iliof the fuse. The inner flange extends over the edge of the timing disc Hi and precludes'flaring or warping of the disc on for-ward set back, which might be sufficient to cause the edge of the disc it'o'ci-lear the projection and release lever 10 were it not prevented. This inner flange has anot'eh for accommodating the projection 15 and in order to insure proper alignment of the notch with the projection two locating pins I28 and 129 are provided in the base *l-ZO, which enter notches in the lower flange of the ring I26 when the ring is properly oriented. These pins are shown in Fig. 10.

Additional means for securing the fuse to the base 'l-Zli is provided in the form of "two screws such as I30, Fig. 1, which pass through the base, the heads being countersunk; through the plates I l-.'2l, and are threaded into the block l9. The holes in the base for these screws are indicated at l3l and 132, Fig. 10, while the corresponding holes in the plates are indicated at 833 and IE4, Fig. 3.

When the fuse is properly assembled to the base 12! the opening in the detonator es, Figs. 3 and 4, is'in alignment with the opening 825 in the base. The opening I25 is a firing passage which leads to a chamber in which the booster detonator I 2'] is'loca ted. This chamber is partly closed by a threaded thimble I22, which retains the booster det'onator in place.

Communication between the detonator 90 and the firing passage I25 is normally blocked by a centrifugal safety device, as shown in Figs. 1 and 10. This device includes a slide I35, located in a recess in the base and having an opening I38. The slide I35 is normally locked by a second slide I36, which is pressed against slide I35 by a spring 131. The slide I36 and spring I31 are also located in the recess in the base, the depth of which is slightly greater than the thickness of the slides. These slides are adapted to move radially under the influence of centrifugal force, first slide I36 and then slide I35. The movement of the latter slide brings the opening I38 into alignment with the firing passage I25, shown dotted inFig. 10. The slide I35 is locked in operated position by spring I39, the end of which drops into a notch in the slide. It will be noted that the slides move in directions which are 90 degrees apart, so that an accidental shock which might momentarily displace slide I36 will have no effect'on slide I35.

The sleeve is locked by means of a screw I40. After the sleeve I21 has been screwed down tightly the hole for screw I40 is drilled and tapped and the screw is inserted.

The setting capis indicated at I4I, Fig. 1, and is shown in Fig. 8. The setting cap rests on the base I26 and is rotatably secured thereto by means of the sleeve I21 and a retaining ring I42 made of stiff wire, which lies partly in a groove in the setting cap and partly'in a groove in the sleeve. As shown in Fig. 8, before the setting cap is assembled to the base the ring I42 is located wholly in the groove in the setting cap,

. which makes it possible to place the cap in position on the base. The screws I43-I46 are then turned in tightly which causes the ring to enter the groove in the sleeve at a plurality of points.

I The upper wall of the groove in the sleeve is tapered, which causes the setting cap to be held tightly to the base when the ring is forced into the groove.

When the setting cap is placed in position on the'base I20 it must be so oriented that the setting pin I41 enters the notch I56 in the upwardly bent leaf II of the timing disc I4. Before tightening the screws I43I46, and while the setting cap is freely rotatable on the base, the fuse is set to zero by rotating the member I48 with a screw driver until the distance between the setting edge I52 on the base and the setting edge I53 on the setting cap is exactly correct. A suitable gauge is used for this purpose. The set screw I49 is then tightened up to: lock member I48 and the screws I43I46 are turned in to couple the cap to the base as previously described. It will be appreciated that the nature of the coupling is such that considerable force is required to rotate the cap, which insures that the zero adjustment will not be disturbed by ordinary handling.

The setting cap I M has a pair of weights I54 and I55, supported thereon by means of a spring I56, which are operated momentarily by set back when the shell in which the fuse is used is fired. The operation of the weights is effective to fiatten out the leaf I5I on the timing disc I4 so as to disengage it from the setting pin I47. The

arrangement will be clear from Fig. l and 8.

The upper cap or nose I5! is secured to the setting cap by screw threads and is assembled last. Within the nose there is a longitudinally movable striker I58 having a steel anvil at the lower end to engage the striker pin 33. The

10 striker I 58 is normally locked against movement by means of two centrifugally operated members I69 and I6! which are located in radially disposed bores and which have projections I62 and I63 at their inner ends which register with an annular groove in the striker. This groove has a tapered upper wall and since the projection I62 has a corresponding taper the member i633 is normally locked against outward radial movement. The projection I63 is cylindrical so that it does not interfere with movement of member I6I, but the latter is locked by the set-back pin I64, the end of which enters an annular groove in member I6I. Spring I65 normally holds the set-back pin in position. The shank of the pin has a close fit in the opening provided for it, while the head of the pin has a very loose fit'in the bore which contains spring I65, so that when set back occurs the pin instantly tilts in one direction or another, depending on where it is engaged by the spring, and the shank of the pin cannot re-enter the opening in which it is normally located. The operation of the set-back pin releases the member I6I, which moves utward by centrifugal force and withdraws the projection I63 from the groove in the striker. The locking member I6!) is now able to move outward also, moving the striker I58 in a forward direction far enough to enable the tapered projection I62 to leave the groove in the striker. These operations unlock the striker for backward movement upon impact with an object against which the shell is directed.

After the striker I58 has been unlocked as described, it is still supported by the collapsible copper shell I66, which yields upon impact and permits the striker to fire the detonator by means of the pin 33 and firing spring 9I. In fuses of the usual construction, which are not provided with locking means for the striker, the support I66 must have considerable strength to withstand the set back action on the striker and to give a reasonable amount of protection against accidental shocks. The stronger the support I66 is made, however, the less sensitive is the fuse to impact and accordingly it has been the practice to make the striker of magnesium, to reduce its weight to a minimum. This reduces the set back effect to a minimum and makes it possible to use a fairly weak support I66, with the result that the fuse is reasonably sensitive to impact. Magnesium is not a good material for the striker, however, being mechanically weak, and the use of a weak support I66 gives little protection against accidental shocks or blows impinging on the nose of the fuse during handling.

From the foregoing the advantages of the locking means for the striker will be appreciated. The striker is positively locked against displacement by any accidental blow, and a shell containing the fuse can be dropped to land on the nose without danger. The striker is also positively locked against set back, which permits it to be made of more substantial material than magnesium. Finally, the support I66, being relieved of its former functions, can be made very weak, strong enough only to prevent the actuation of the striker by rain drops encountered by the shell in its flight, with the result that the fuse has the maximum sensitivity.

The operation of the various parts has been explained more or less in the course of the preceding description. Nevertheless, it will be of assistance to a full understanding of the invenl1 tion to give a brief resume of the operations in the order in which they take place, omitting reference to details of construction which have already been described.

For this purpose it will be assumed that the complete fuse as shown in Fig. 1 is assembled into a shell. As shown in the drawing the base I20 -is provided with screw threads by means of which the fuse is'secured to the shell in the usual manner.

The fuse is set by means of a fuse setting device which is provided with means for engaging the setting edges I52 and I53 to rotate the setting cap I4I relative to the base I20. Since the fuse is rigidly secured to the base the rotation of the setting cap rotates the timing disc I4 relative to the rest of the fuse. V The direction in which the timin disc is rotated in the setting operation is shown by the arrow in Fig. 2, and the extent of rotationdepends on the time interval desired, as will be understood;

When the shell is fired the operations which result from set back are the first to take place and occur simultaneously. Staging with the nose, and mentioning the operations briefiy, the set-back pin IEid moves into the spring cavity and releases the locking member I5I. In the setting cap the weights I5d and I55 strike the leaf I5] a blow which flattens it out and disengages it from the setting pin Id'i. Finally, in the timing mechanism the set-back pin III moves out of the path of the member 59 which supports the firing pin.

The next thing to take place is forward set back which occurs when the driving band strikes the rifling in the gun. Forward set back produces no useful effect. It tends to warp the timing disc 74 which is restrained, however, by the flange on the ring I 26.

As the shell begins to travel down the barrel of the gun it is rotated by the rifling at an increasing speed and attains a high rotational velocit by the time it leaves the muzzle of the gun. Centrifugal force is thus developed which results in starting the timing mechanism and other. operations which will be described briefly.

In the nose of the-fuse the-locking member IGI, having been, released by the set-back pin I63, moves radially outward, followed by 'afsimilar movement of the locking member I60. This unlocks the striker I58.

In the'timing mechanism, the driving

weights

34 and 35 start to move outward'and together with the springs I16 and Ill apply a driving torque to the'shaft 3'6. The escape wheel 45, normally lockedby the two detents 63 and St, is released by outward movement of these detentsyandat the same time or an instant later the starting lever BI rotates on its pivot to give an initial impulse to thepallet arm 4?. The timing mechanism is thus started'and continues to ru'nfro'm 'power'supplied by'the'springs and'the driving weights. In the operation of the timing mechanism the shaft 30, the safety disc I2, and the timin discarerotated in a clockwise direction as seen in Fig. 2.

In the base of'the fuse centrifugal force operates the slides I36 and I35 successively "and the opening I38 in slide I35 becomes aligned with the firing passage I25 to provide communication between the detonator 90 and the booster detonat'or I2I.

Centrifugal force also tends to operate the safety lever 95,'the clocking member 59 for-the firing'pih, a'ndthe levers "I0 "3.116.103, blit these "assai ed 12 parts are all restrained against movement for the time being.

The rotation of the safety disc I2 causes the hook I04 thereon to move relative to the hook I65 on the lever I03 and after an interval of one-half second has elapsed the hooks become disengaged, thus releasing lever I133. The lever accordingly rotates shaft 'III'I in a clockwise direction, Figs. 2 and and releases the safety lever 95, which rotates in a clockwise direction on its pivot 91, due to centrifugal force acting on weight 96. This movement of the weight and lever leaves the firing spring "91 free to operate.

The fuse is now'fully armed and ready to fire the shell, either by impact or at the expiration of the time interval for which the timing disc was set.

If the shell presently strikes the object toward which the shot was. directed, the striker I58 is forced backward relative to the fuse and shell and the detonator is exploded by means of the pin 33 and firing spring '9I. The explosion of detonator 98 sets off the booster detonator I2I which explodes the booster charge usually rovided below the fuse, which in turn explodes the main charge in theshell.

If the shell does not strike the target, the shell is exploded by operation of the timing mechanism. In the operation of this mechanism the safety disc 12 and the timing disc i l rotate in a clockwise direction, Fig. 2, aspreviously mentioned. In approximately one second the arm I3 on the safety disc clears the projection 15 on lever '55, leaving the lever under the sole control of the timing disc 1d. The rotation of the timing disc causes. the notch with which it is provided to gradually approach the projection '55 and at the expiration of the time interval for which the fuse. was set'the notch becomes aligned with the projection, thus releasing the lever III. Centrifugal force acting on weight II now rotates the lever l9 and shaft 62 and the latter releases the locking member 59. The member 59 is also acted on by centrifugal force and rotates in a clockwise direction, Fig. 7, to release the firingpin 56.. Upon the release of the firing pin it strikesfthe firing spring GI "a blow which explodes the detonator "96 and the explosion of the shell takes place as previously described.

The rate-of the timing mechanism is only very slightly affected by the rotational velocity of the shell, that is, the rate is substantially the same in a shell having a low rotational velocity as it is in a shell having a high rotational velocity. The fuse may be used with good results, therefore, in variouslkinds of shells.

The invention having been described, that which is believed to-be new and for which the protection ofLetters Patents is desired will be pointed out infthe, appended claims.

I claim:

1. In a combination fuse, clockwork mechanism including ahollow'mainpower shaft and a gear train driven thereby, point impact firing mechanism including a striker pin extending through said shaft, a firing pin extending parallel to said striker pin, means including a timing disc on said main shaft'for actuating said firing pin, a firing spring eX-tending beneath'said striker pin and said firing pin-and adapted to be operatively engaged by said pins, a detonator, and means including said firing spring for exploding said detonator responsive to actuation of. said striker pin or said firing pin.

'2. In a mechanical time fuse, clockwork mech- 13 anism having a shaft, a safety disc and a timing disc adapted to be rotated by said shaft, said safety disc being fixed on said shaft and said timing disc being adjustable on said shaft to a variable starting position determined by setting the fuse, a detonator, a spring actuated firing pin, locking means for holding said firing pin in cocked position, a firing member adapted to be operated by said firing pin to explode said detonator, a centrifugally operated safety device normally blocking the operation of said firing member, latch means normally holding said safety device against operation, said latch means including a rotatably mounted shaft, means mounted on said shaft and controlled by rotation of said safety disc for releasing said safet device, and means controlled by rotation of said timing disc for releasing said locking means.

3. In a combination fuse, clockwork mechanism including a hollow main power shaft and 2 a gear train driven thereby, centrifugally operated weight means for rotating said shaft, point impact firing mechanism including a striker pin extending through said shaft, a spring loaded firing pin, extending parallel to said striker pin, locking means for holding said firing pin in cocked position, means including a timing disc on said main shaft for unlocking said firing pin, a detonator, and a firing device adapted to be engaged and operated by said striker pin or said firing pin, depending on which is first actuated, toexplode said detonator.

4. A combination fuse as claimed in claim 3, wherein the striker pin and the firing pin have a common arming device, comprising a centrifugally operated member normally preventing operation of said firing device.

5. In a mechanical time fuse, clockwork mechanism including an axial main shaft and a gear train driven thereby, a pinion on said main shaft, a pair of toothed gear sectors supported on pivot pins for cooperation with said pinion, a pair of drive said shaft when the fuse is rotated.

JEAN FINK.

REFERENCE S CIT ED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 616,317 Hale Dec. 29, 1898 966,038 Moore Aug. 2, 1910 1,172,637 Semple Feb. 22, 1916 1,693,516 Junghans Nov. 27, 1928 1,726,325 Varaud Aug. 27, 1929 1,744,194 Adelman Jan. 21, 1930 1,758,635 Wieser May 13, 1930 1,786,664 Liebergeld Dec. 30, 1930 1,792,631 Deevy Feb. 17, 1931 2,071,350 Mathsen Feb. 23, 1937 2,083,564 Hofstetter June 15, 1937 2,129,692 Hottinger Sept. 13, 1938 2,190,157 Junghans Feb, 13, 1940 2,231,581 Junghans Feb. 11, 1941 2,236,037 Sekella Mar. 25, 1941 FOREIGN PATENTS Number Country Date 455,908 France June 5, 1913 145,829 Great Britain June 28, 1920 284,968 Great Britain Feb. 9, 1928 396,171 Great Britain Aug. 3, 1933 603,660 Germany Oct. 5, 1934