US2126047A - Mechanical time fuse - Google Patents

Description

938; E. H, SCHENK 2,126,047

MECHANICAL TIME FUSE Fiied Nov. 2, 1935 2 Sheets-Sheet 1 INVENTOR mmz/V. ail/4 Aug. 9, 1938. j s. H. SCHENK ,1

MECHANICAL 'IIME FUSE Filed Nov. 2, 1935 2 Sheets-Sheot-Z R u E:

*si y Patented Aug. 9, 1938 UNITED STATES DECHANICAL TILE FUSE Edouard H. Schenk, New York, N. Y., assignor,

by direct and mesne Brandt, Paris, France assignments, to Edgar Application November 2, 1935, Serial No. 47,914.

15 Claims.

This invention relates to a mechanical fuse for artillery projectiles, and more especially to a mechanical time fuse of the type described in 7 my co-pending applications for Letters Patent of the United States Numbers 38,012 and 38,013, filed on August 27th, 1935 and Number 41,990, filed on September 25th, 1935, in which the hollow body of the fuseJs formed by a fixed base and an adjustable setting cap rotatably mounted 10 on said base and in which a rotor housing the clock mechanismof the fuse and controlling the release of a trigger and hammer mechanism is set in angular position before the fire by means of the setting cap and is driven during the flight 16 of the projectile in opposite direction by a compression spring motor at a speed governed by said clock mechanism.

The possibility of having a great number of different angular setting positions, i. e., the ac- 20 curacy of fuses of this type depends largely upon the bulk in diameter of the rotor, acting as a timing circular member, and on the working fit and adjustment of the partsof the trigger mechanism of the fuse. In practice the diameter of the rotor cannot be increased beyond certain limits without narrowing the range of possible adaptations of the fuse to projectiles of small caliber and it is very dimcult to adjust with the required precision, the parts of the trigger mechanism and to prevent that this mechanism, by its friction upon the rotor, acts as a brake on the clock mechanism of the fuse.

The object of the present invention is to further simplify and improve a mechanical fuse of this type and especially to increase the diameter of the timing circular organ of the fuse without increasing the diameter of said rotor and to release the hammer or firing pin at the end of the trajectory without using to that effect a spehis] trigger mechanism. The main feature of my invention through which this object is attained is, on the one hand, to provide the release notch, which in fuses of this type controls the release of the hammer,

intheflxedbaseof thebodyofthefuse.andon the other hand, to fasten-the hammer or firing pin of the fuse in the center of the bottom of said rotor, and to reverse the direction of action of the compression spring, 1. e., to have a mainspring 60 with a pushing action instead of a pulling one. It

becomes thus possible to 'do away with the intricate trigger mechanism and with the separate percussion spring which are-otherwise-requlred in fuses of this kind.

as Other features of my invention are the provision of a bore safety device preventing any premature burst of the projectile if the fuse by mistake is fired without having been set at all or after having been set below the minimum or above the maximum setting time, of rolling means 5 (rollers or pinions) which project outside the periphery of the rotor and cooperate with a notched circular part of the fuse body so as to act as timing organ. of a relatively very strong compression spring, which act successively as 1 mainspring and as percussion spring, of balancing means for distributing equally around the periphery of the rotor the forces acting upon said-rotor in order to improve the dynamic balance of the fuse and-in the'case of the adaptation of my invention to a combination fuse-of a simple and efiicient device for arming the primer-plunger of the fuse and preventing its premature creeping toward the firing-pin during the trajectory of the projectile.

With the foregoing and other objects in view which will appear as the description proceeds, my invention consists chiefly in the novel use of the fixed base of the body of the fuse as the fixed part of the timing and release mechanism of a mechanical fuse and in the complete suppression of a separate trigger mechanism to effect the release of the hammer or firing pin of the fuse at the end of the trajectory of the projectile, as well as inthe novel arrangement and combination of parts and in the details of construction hereinafter described and claimed, it being understood that chan es in the precise embodiment of the invention herein disclosed may be 3 made within the scope of what is claimed without departing from the spirit of the invention.

I will now proceed to a detailed description of the invention in connection with the drawings, in which I have shown two embodiments of said invention: one to a mechanical time fu'se (Figures 1 to 4) and one to a so-called combination fuse, that is a fuse able to function both as time fuse and as percussion or impact fuse (Figures 5 to 10).

In the drawings:

Figure 1 is an elevation with part in axial section of said time fuse, showing the moving parts of the fuse in their normal position of rest;

Figure 2 is a bottom view of the setback weight used to compress the mainspring of the fuse;

Figure 3 is a transversal section made on line A-A of Figure 1 and showing diagrammatically the gears of the clock mechanism of the fuse;

Figure 4 is a transversal section made on line B-B of Figure 1 with part broken to show one of the release notches of the fuse;

Figure 5 is an axial section tion fuse similar to Figure 1;

Figure 6 is a transversal section made on line A-A of Figure 5;

Figure 7 is a transversal section made on line B-B of Figure 5;

Figure 8 is a transverse] section made on line 0-0 of Figure 5 through the body of the fuse and partly a plan view of the rotor with part in transversai section through this rotor;

Figure 9 is a partial axial section similar to Figure 5 showing a modification of said combination fuse and Figure 10 shows a detail of this modification.

. In the drawings, i represents the base of the fuse, 2 the usual setting slot for engagement with a corresponding pawl of the setter and 9 a steel band fastened on the upper edge of said base, which carries the usual scale graduated in seconds and tenths of seconds. This band is provided with an inside projecting upper rim or flange 9A, out so as to form a circular series of sharp steel points, converging toward the center of the fuse. 45 indicates the setting cap, or brass cap, which is rotatably mounted into the base I and held against axial displacement in relation to said base by means of a set screw or shoulder screw 99, screwed in the base I and working in a continuous circular groove M. out near the bottom of said setting cap. This latter is also provided with the usual setting slot (not shown) and with a steel band 6, fastened to its lower edge and on which is marked the usual index, which registers with the graduation 0 of the scale 3 in the normal position of the fuse. This band 8 is flush with the graduated band 3 and is provided, as this latter, with an inner projecting flange @A, cut so as to form a circular series of sharp steel points. An annular groove 70 is cut behind the bands tend 9, half in the setting cap A and half in the base i. A ring or washer H of soft metal, for instance of lead, is squeezed between said cap 6 and base i, opposite the steel points BA and EA.

These parts 3, 9A, 9, 6A and ii cooperate at the time of the setting of the fuse to couple positively the setting cap t to the base i as described in my pending application Number 41,990 of September 25th, 1935.

FA shows the top cap of the fuse as a disk or washer clamped in the bore of the setting cap between a shoulder of this bore and the upper edge of said cap, which is rolled over a wire so as to form an abutment for said disk. Thus assembled, the base 8, setting cap 6 and top cap IA form the hollow body of the fuse.

A compression spring 9 is mounted in the axial of the combinacylindrical bore of the setting cap 6. The uppermost coil of this spring is held in a circular recess provided in a setback weight 02A, while its lowermost coil is secured in an opposite circular recess provided in a sleeve 89A. Both this weight and this sleeve are prevented from turning in the bore of the setting cap by keys I23, 29A, working in longitudinal keyways 4A, 6B.

86 shows a hollow shaft arranged inthe axis of the fuse, which constitutes the mainshaft thereof.; In the top of this driving shaft are provided four mortises iEA cooperating with four corresponding tenons I20 provided in the bottom ofv the weight i2A (Figure 2) during the linear acceleration of the projectile.

Two helical grooves 19 with progressive pitch are symmetrically cut into the periphery of the mainshaft I6. 20 indicates a pair of diametrically opposed conical rollers which are pivotally mounted in two radial pins secured to the sleeve I3A. These pins project beyond the periphery of this sleeve so as to form the keys 29A, while each roller 20 is permanently engaged into one of the grooves it.

The mainshaft i6 is made in one piece with the cover'or top of a cylindrical casing H, which con-' (not shown) to which is secured the lower end of the hairspring 36 of the fuse, which is lodged in a steel tube 31- The planetary pinion 22 is in constant mesh with an annular gear 23, freely mounted in the cover of the rotor 2i, but coupled to the setting cap 9 by means of two diametrically opposed ears 23A (Figure 3), working in two corresponding longitudinal keyways MB, out throughout the bore of largest diameter provided at the bottom of the setting cap 9 to give room to the cover of the rotor 2!. The rotor 2| also is normally coupled and moreover axially held to the setting cap t by The .top end 32 of this spindle carries a staff means of a radial pin 62, whose inner end projects then in a radial hole 62A of the cover of the rotor, while its outer end abuts against the cylindrical end of the set screw 60. The cylindrical body or bottom of the rotor 2| is freely mounted in a corresponding bore of the base i and carries four radially projecting releaserollers MA, which normally hang over four corresponding release notches 59A, but which run over a circular track 45A in one direction during the setting of the fuse and in opposite direction during the flight of the projectile. The relative angular position of these four rollers and notches is unsymmetric in order that they will simultaneously register only in their normal position of rest (as shown in the drawings) and that no premature release may occur during the rotation of the rotor 2| when each'one of these rollers jumps across one of the three other notches. The track 65A is slanted toward the axis of the fuse in order to center the rotor 2! in the axis of the fuse-and this track is provided with a small outer cylindrical edge in order to guide the rollers 66A along a true circular Path.

The firing pin 6'! of the fuse is fastened in the center of the bottom of the rotor 2| and serves as steel surface bearing for the lower pivot of the spindle 30. 64 and 65 show respectively the usual primer and detonator screwed in the bottom of' the base i.

The weight HA is provided with a peripheric groove I5, in which are lodged three centrifugal segments 76 which expand under the action of the centrifugal force as soon asnear the end of the setback of this weightthis groove 75 registers with a shoulder 11 of the setting cap.

Instead of having the fixed track 65A, and the four release notches 59A formed in the bottom of provided in-the bore 1 the bore of the base I and the four moving rollers 44A, unsymmetrically arranged around the periphery of the bottom of the rotor 2 I to control the release of the firing pin 41 at the end of the trajectory of the projectile,'one could obviously have a moving track formed by a collar or circular projection of the bottom of the rotor 2|, three or four release notches out throughout this collar, and three or four corresponding fixed rollers, unsymmetricaily mounted in the bottom of the bore of the base I under this moving track.

Similarly one could have one, two or three helical grooves cut in the inside periphery of the sleeve "A and one, two or three corresponding driving rollers, pivotally mounted on the outside periphery of the mainshaft I6, instead of the pair of driving rollers III, mounted in the sleeve ISA and of the two corresponding helical grooves I! cut into the mainshaft I6.

One could also reverse the disposition of the firing mechanism of the fuse, that is have a fixed firing pin, secured in the center of the bottom of the bore of the base Land a shiftable primer fastened to the bottom of the rotor 2|.

The action of the mechanical time fuse shown in Figures 1 to 4 of the drawings is as follows:

Normally, i. e., before the setting, the movable parts of the fuse are in the position shown in the drawings. In this position the fuse is perfectly safe in handling as the rotor ii is positively locked by the pin or bolt 62 and this latter is immobilized by the set screw 40. The fuse is also perfectly stable in storage as the single spring 9 serving as mainspring and as percussion spring is then uncompressed.

When the fuse is set, the setting cap 4 and the rotor 2 I, positively coupled to this cap by the pin 62, are solidarily rotated to the desired angular position, in accordance with the fuse range data, by the fuse setter pawls engaging the setting slots of respectively the base I and the cap 4. The fit of the pin 62 in the hole 62A issuch that the ensuing friction prevents the occurrence of any radial movement of this pin when, during this rotation the outer end of this pin goes away from the cylindrical end of the set screw 40 and opens in the cleared part of the circular groove 4|. Even if this were not the case, no accident could occur from the radial displacement of this pin 62 as, during this rotation, the release rollers 44A enter on the plain part of 'the track 45A as soon as this set screw 40 releases this pin 62 and, as when one of these rollers registers with one of the release notches 58A, the three others remain on said track due to the unsymmetrical disposition of said rollers and release notches around the periphery of the rotor 2|.

It must be noted that this fuse can be setand reset-in either direction and in any angular position as there is no stop or abutment limiting the rotation of the setting cap 4. If the fuse is set by mistake below the minimum setting time (usually half a second) no mishap or accident may occur during the loading or in the bore because in-that casepart of the cylindrical end of the set screw; 40 is still in the path of the pin or radial bolt 62 and therefore the fuse cannot burst after having been fired. The'same is true if the fuse is set by mistake. beyond the maximum setting time, say exactly of 360, be-

cause in this case-though the four release rollers 44A come back in their normal position in which they register again with the four release notches 58A--the pin 82 comes simultaneously back in front of the set screw 40.

It may thus be seen that the range of the different angular possible setting positions is limited by the diameter ofthe cylindrical end of the set screw 40 and is included in an angle of about 350 to 355", the remaining 5 to coristituting the angle of safety of the fuse.

If the fuse is fired by mistake without having been set, it cannot burst as the pin is still in this angle of safety, thus locking positively the rotor 2| against axial and angular displacement.

As soon as the setting operation is performed, a pair of diametrically opposed cams or eccentrics, forming part of the release mechanism of the setter, squeeze or crush the bands 3 and 6 in two diametrically opposed points so that some of the steel points 3A and 5A are empaled in the lead washer II;

The setting cap 4 is thus positively coupled to the fixed base I as the band 3 is fastened to this latter, while the band 6 is fixed to the former. The release rollers 44A are, therefore, immobilized in their set angular positiomwhich determines the duration of the flight of the projectile during the loading operation and-as will be seen thereafter-also during the firing operation.

Upon the firing of the projectile, the setback weight I2A drops back by inertia, thus compressing the spring 9, until the tenons I2C enter in the mortises 16A, while the pin 62 penetrates into the circular groove 4|, thus releasing the rotor 2|. As long as the linear acceleration of the projectile remains positive, the tenons IZC remain pressed against the bottom of the mortises ISA and, therefore, the rotor 2| remains nevertheless coupled to the setting cap 4 through the action of the key I2B. Near the end of this setback of the weight I2A, the centrifugal segments 16 expand under the action of the centrifugal force in the bore of larger diameter'of the setting cap 4 formed under the shoulder I'I.-

Near the end of the positive acceleration, the force of inertia pressing down the weight I2A is counterbalanced and immediately afterwards overcome by the energy stored in the spring 9 and the weight I 2A is therefore thrust forward until the protuberant parts of the segments I6 come to abut against the shoulder 'I'I. As, in this position, the tenons I2C are disengaged from the mortises ISA, the rotor 2| is then imcoupled from the setting cap 4 and, therefore, armed. A straight force, parallel to the axis of the fuse and tending to push or press down the sleeve I3A toward the bottom of the fuse is then immediately applied upon this sleeve.

As this sleeve is prevented from turning by the keys 20A, working in the keyways 43, this straight pushing force is transformed by the driving rollers 20, engaged in the helical grooves I9, into a torque, under the action of which the rotor 2|, carried by the release r llers 44A, starts to rotate back about its axis on the track 45A. This rotation is facilitated by the fact that-save the slight friction of the two keys 23A of the internal gear 23 against one side wall of the keyways 42B and that of the rollers 44A upon the track 45A- there is no friction between the mainshaft I6, together with the rotor 2 I and the hollow body of the fuse formed by the base I and the setting cap 4.

As the pitch of the helical grooves I 9 is progressive, the increase in leverage thus obtained compensates for the diminishing pushing force of the mainspring 9 and the value of the torque applied on the mainshaft I6 remains practically constant during the whole flight of the projectile, in spite of the fact that the mainspring loses progressively its energy. Thus these grooves l9 act as the i'usee of a clock. I

. During all of its backward movement under the pushing action of the mainspring, the sleeve |3A is well guided along the bore of the setting cap by its periphery, in which an annular groove is cut in order to reduce the friction. The angular speed of the rotor 2| thus driven by the mainspring 9 is regulated by the action of the hairspring 36 cooperating with the balance 29 and the cylinder 28 to check the rotation of the escape wheel 21, to which the motive force is transmitted through the train 25, 26, the planetary pinion 22 and the fixed internal gear 23.

The release rollers MA are thus brought back in their initial position opposite the release notches 59A. As .there is much more energy stored in the mainspring 9 than is required to drive back the rotor 2|, even when it has been set for the maximum setting time, i. e., of between 350 and 355", the firing pin 1 carried by the rotor 2| is violently thrown upon the primer 6% under the action of this supplementary energy as soon as the rollers 44A come to register with the release. notches 59A and drop through said notches. The primer 66, thus stricken by the firing pin 61, detonates instantaneously first the detonator 65 and then the bursting charge in the projectile.

In the second embodiment of my invention, shown as applied to a combination fuse in Figures 5 to 10, the base of the fuse is in 3 parts: two fixed ones and IA solidarized by means of 3 screws 8| and an inner one 18 mounted with a slight axial play so as to act as a shock absorber during the positive acceleration of the projectile. This play is limited in one direction by a shoulder 6F of the setting capi and in the other direction by the bottom of the bore of the part I. This shiftable'inner part 18 is angularly coupled to the two fixed parts I, IA by means of the same screws 8| which are provided with cylindrical projections or keys working in three longitudinal keyways 80. Ashock absorbing spring 83, normally uncompressed, is interposed between a conical head IQ of this inner part I8 and the top of the intermediate part IA.

In the outer periphery of this intermediate part IA is .provided a circular groove MA, interrupted at 62 so as to form a stop or. abutment for an inside projection or lug 40A, fixed to the lower edge of the setting cap 3. This lug prevents any axial displacement of the setting cap with respect The cylindrical projection i6 forms with the setback weight |2A a telescopic tube or shaft, being provided with two longitudinal keyways IBB cooperating with two corresponding longitudinal keys |2D of 'the weight |2A. This latter is nor-/ mally coupled to the setting cap a by means of two diametrically opposed ears |2B, engaged in two corresponding keyways 4A of the setting cap 4. 4E indicates a cylindrical clearance of the setting cap 6, A'Ctwo mortises into which penetrate the ears |2B when the weight |2A reaches the end of its setback and 4D a circular shoulder acting as a step to limit this setback.

-Three helical grooves I 9A with progressive pitch are cut into the inside periphery of the shock absorber It. The lower ends of these grooves open into the three release notches 59A. As the three corresponding release rollers 20A, in this form, are dragged away from the level of these release notches 59A during the setting operation. as they are engaged into said three grooves |9A, it is no more necessary that these release rollers and notches be unsymmetrically disposed around the periphery of the rotor 2|.

In this form, the first pinion 22A of the train of the clockwork of the fuse is normally loosely mounted upon a shaft 85, through which is fixed a steel key 86 projecting on both sides so as to form two diametrically opposed steel blades. A spring 81, which is interposed between the pinion 22A and the first wheel 25, normally holds this pinion above these steel blades. This pinion is in constant mesh with an intermediary pinion 8%, which, in its turn, is in constant mesh with a helical rack 233, having the same progressive pitch as the three grooves |9A. A clearance WA is provided in the shock absorber 18 to give passage to this intermediary pinion 84 when the rotor 2| sets back under the action of the spring 9 at the end of the trajectory.

68 shows the primer-plunger of the fuse which is slidably mounted in a corresponding cylindrical bore provided in the center, of the bottom of the base A concave groove MA is provided in the periphery of said plunger. The plunger 64 is normally held back against the detonator 65 by two diametrically opposed centrifugal bolts 61 submitted to the action of two springs 61A. The force of these springs is adjusted by means of screws 613 in such a way that no release of the primer may occur before the fire, i. e., that the plunger 641s armed only when the centrifugal action reduces this force to a value still suflicient to prevent the creeping of the plunger 64 towards the firing pin during the trajectory but incapable of preventing thiscre'eping at the impact of the fuse.

In this form, the rotor 2| does not need to be normally locked in axial direction in order to prevent a premature burst in the bore, as the three release rollers 20A do not hang over the release notches 59A as in the preceding form, but lean upon the beginning of the three helical grooves ISA and as the rotation in counterclockwise direction of the rotor 2| is then prevented through the intermediary of the telescopic shaft I6, I 2A and of the setting cap t by the lug 10A abutting against the stop 62. I

It will be seen that, therefore, the fuse can be set only in clockwise direction, when the setting cap 4 is in the normal position shown on the drawings, and that beyond a maximum setting angle of between 350 and 355, the rotation of the setting cap will be stopped by the other side of the stop 62. During the setting, the rotor 2| is dragged angularly away from the release notches 59A by the rotation of the setting cap 2, to which it is then coupled throughthe telescopic shaft Hi, |2A, and axially dragged away from the primer-plunger 64 through the action of the rollers 20A ascending the grooves |9A. The spring 9 is thus compressed.

In the position shown in the drawings the fuse is normally set for its'minimuni setting time (usually half a second); thus, if fired without further setting, it will burst at the expiration of this short time.

Upon the firing of the projectile, the setback weight |2A drops back by inertia, thus completing the compression of the spring 9, until. the ears I23 enter in the mortises 4C, while the pinion 22A sets back against the action of the weak spring 8] and of the wedge-like steel blades 86, which are driven into its inner periphery and thus couple this pinion to the shaft 85. As long cylindrical clearance 4E, the rotor 2| is then axially slidable in said body to compress this' uncoupled from the setting cap 8 and therefore armed. As the spring 9 presses down directly upon the rotor 2|, the rollers 28A start then to rotate back down the helical tracks I9A, while the planetary pinion 84 follows down the helical rack 23B and thus drives the clock mechanism through the pinion 22A, now coupled to the shaft 85, upon which is keyed the first wheel 25. When, in the course of this back movement, the rollers 28B reach their initial normal position, the rotor 2| continues to rotate under the action of the spring 9 until these rollers register with the'release notches 59A.

If, during the flight of the projectile, the nose cap I meets an obstacle, or on impact on the ground, if the time mechanism of the fuse has not functioned before, the primer-plunger 84 is driven forward by the shock against the action of the springs 81A, then weakened by the action of the centrifugal force, and thus the firing-pin 41 is jammed into the primer composition, which detonates the detonator 85.

In the modification shown, Figures 9 and 10, the three rollers 20A are combined with the planetary pinion 84 in three double angle pinions 88, while the three helical tracks ISA and the helical rack 23B are combined in three helical racks 283 with conical radial teeth. The three inner angle pinions 88 mesh with a double gear 88, having both radial and axial teeth and resting upon a ball bearing 98.

I claim:

1. In a mechanical fuse for an artillery projectile: a hollow fuse body, a rotary hammer carrier axially slidable in said body, a primer axially mounted in said body, a clock mechanism lodged in said carrier, a powerful compression spring normally uncompressed and arranged in said body in the axis of the fuse, a setback weight spring upon the firing of the projectile, centrifugal means to hold this weight in its back position pressing upon said hammer carrier, means to transform the pushing force of this spring into a torque driving the clock mechanism of the fuse during the flight of the projectile andmeans to apply the remaining energy of this spring upon said hammer carrier at the end of the trajectory so as to drive the hammer down upon said primer.

the periphery of said rotor, to control the thrusting of said firing pin upon said primer under the action of this spring at the end of the trajectory.

3. In a mechanical fuse a hollow fuse body formed of a fixed base and an adjustable setting cap, a setback weight slidably mounted in the axis of said setting cap, a cylindrical rotary timing member carrying a firing pin, slidably mounted in the axis of said base and normally coupled to said setting cap, a clock mechanism lodged in said timing member and a powerful compression spring interposed in the axis of the fusebetween this weight and this timing member so as-to act both as mainspring for this clock mechanism and as percussion springv for this firing pin.

4. In a mechanical fuse for an artillery projectile: a hollow fuse body formed of a fixed base and an adjustable setting cap, a compression spring motor arranged in said body, an axially slidable rotor driven by said motor during the fiight of the projectile, a'clock mechanism entirely lodged in said rotor to govern the angular speed thereof, a spring-pressed hammer carried by said rotor and a timing and release mechanism to control the release of this hammer and comprising a circular track formed in said base, release notches provided in said track and release rolling means radially mounted on the periphery of said rotor.

5. In a mechanicalfuse as claimed in claim 4: a mainshaft carried by the rotor and pivotally mounted in the axis of the setting cap, a powerful cylindrical spring of the compression type lodged in thexbore of said cap around said mainshaft, an axially slidable setback weight guided in said bore and coupled to said setting cap and a driving sleeve screwably mounted upon said mainshaft and also coupled to said setting cap.

6. In a mechanical time fuse as claimed in claim 4: a mainshaft pivotally mounted in the axis of the setting cap, a setback weight slidable in said setting cap, means to keep this weight constantly coupled to said setting cap, a compression spring keeping this weight and this mainshaft normally apart and a mortise and tenon coupling between the bottom of this setback weight and the top of said mainshaft which couples momentarily said mainshaft to the setting cap during the acceleration when this weight sets back against the action of said spring.

7. In a mechanical time fuse for artillery projectiles: a hollow setting cap, a compression mainspring-lodged in the hole of said cap, a setback weight axially slidable in said hole to compress said mainspring upon the firing of the projectile and a top cap to hold this weight, this cap being clamped between a shoulder of this hole and the upper edge of said setting cap,

a driving sleeve screwably 'nounted upon said mainshaft, a pair of diametrically opposed pins radially mounted through this driving sleeve and projecting outwardly into longitudinal keyways' provided in the inside periphery of said setting cap and a pair of rollers mounted in the inner end of said pins and permanently engaged in helical grooves provided in the periphery of said mainshaft and having a progressive pitch.

9. In a mechanical time fuse for artillery projectiles: a hollow body formed of a fixed base and an addustable setting cap, a cylindrical firing pin carrier slidably and rotatably mounted in the hole of said body, a compression spring pressing upon this firing pin carrier during the flight of the projectile, a centrifugal bolt radially mounted in the bottom of said setting cap and normally engaged in a hole cut in the periphery of this carrier so as to couple it to said setting cap before the fire, and a set screw, screwed through said base and projecting into a circular groove of said cap, which looks this bolt in its active position before the setting of the fuse.

10. A mechanical time fuse as claimed in claim 4, in which the timing and release mechanism comprises at least three release rollers radially mounted on the periphery of the rotor in unsymmetrical positions and at least three longitudinal release notches cut through an inner cylindrical projection of the base and similarly arranged in unsymmetrical positions.

11. In a mechanical time fuse: a clock mechanism comprising a balance wheel, an axial spindle carrying said balance wheel, a steel firing pin aligned with said spindle, and serving as bearing for the lower pivot of said spindle.

12. In a mechanical time fuse as claimed in claim 4: a shock absorber forming part of the base, three release rollers radially mounted at 120 between them on the periphery of-the rotor and three helical tracks cut in the inside periphery of said shock absorber.

13. In a mechanical time fuse as claimed in claim 4: a shock absorber forming part of the base, three release rollers radially mounted at 120 between them on the periphery of the rotor, three helical tracks cut in the inside periphery of said shock absorber and three longitudinal release notches cut at 120 between them in the inside periphery of said shock absorber and opening into the three helical tracks cut in said shock absorber.

14. A mechanical time fuse for an artillery projectile having a clock mechanism, a pinion of the train of said clock mechanism loosely mounted upon its shaft, a wheel keyed on this shaft, a spring interposed between this pinion and this wheel and steel blades formed on this shaft to couple this pinion upon the firing of the projectile.

15. In a mechanical time fuse as claimed in claim 4: a shock absorber forming part of the base, three helical racks cut into the inside periphery of said shock absorber, three double angle pinions pivoted in the cylindrical wall of the rotor and in mesh on one side with these racks and a double gear freely mounted on ball bearings in the rotor and having, on the one hand, a

radial set of teeth in mesh with the other sidev of the double angle pinions and, on the other hand, an internal set of teeth in mesh with the last pinion of the clock mechanism.

EDOUARD H.

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