US2684839A

US2684839A - Hand operated pick

Info

Publication number: US2684839A
Application number: US50206A
Authority: US
Inventors: Rice Charles John
Original assignee: Individual
Current assignee: Individual
Priority date: 1947-09-22
Filing date: 1948-09-20
Publication date: 1954-07-27
Anticipated expiration: 1971-07-27

Description

Jury 27, m54 c. J. RICE HAND OPERATED PICK 3 Sheets-Sheenl l Filed Sept. 20, 1948 wc Tw wv IIIIIIIII i Inventor Char/es J." Rice Attorney July 27, 1954 C, J,-R|CE 2,684,839

HAND OPERATED PICK Filed Sept. 20, 1948 3 VShee'rs-SheeiI 2 F/GB.

Attorney July 27, 1954 c. J RICE HAND OPERATED PICK Filed Sept. 20, 1948 3 Sheets-She@l 3 7 Inventor;

6 Char/e5 J/ vlce A Harney Patented July 27, Y 1954 UNITED STATES PATENT OFFICE Claims priority, application Great Britain September 22, 1947 3 Claims.

This invention is concerned with improvements in or relating to tools for use in excavating and other operations.

Various forms of hand-operated picks for use in excavating operations are already known but all of these function with a swinging action and therefore require a large amount of room for their operation. Known forms of picks cannot for instance be used in excavating a deep hole of say less than about six feet in one transverse direction or in carrying out other similar operations in places where little free space is available.

One' of the objects of the present invention is to provide a hand tool which will perform functions similar to those of a pick but which is operable in places where only little space is available. A further and more specific object is to provide a tool which is particularly suitable for use by a single operator in excavating holes where the available room does not permit of the use of a pick, sledge hammer and chisel or the like. If desired the said tool may further be adapted for performing the functions of a chisel, crowbar or hand-drill for use in making holes or excavations in rock, stone or concrete.

According to the present invention there is provided a hand tool comprising a body portion, a bit, or a chuck or the like for receiving a bit, and a reciprocable plunger movable in said body portion and adapted upon reciprocation to strike said bit and drive it into the work.

The aforesaid body portion is preferably of tubular form and the plunger is preferably in Vthe form of a solid bar, the inner end of such plunger being provided if desired with a ring or the like which makes a good sliding t in the body portion of the device. Such ring or the like may also serve to form a weighted head on the plunger and if desired it may be removably fitted to the plunger so that a ring or the like of weight appropriate to any particular work can be tted. The bit for use with a device according to the present invention is preferably secured to the aforesaid body portion in such a way that it is free for limited sliding movement in an axial direction, so ensuring that when the bit is for instance rested on the work it will be automatically moved to its uppermost position and will thus transmit impact applied thereto directly to the work and not through the body portion.

The means for securing the bit to the body of the device may comprise a chuck having bayonet like slots for receiving radial projections from the shank of the bit and the ends of the circumferentially disposed parts of the said slots may have outwardly directed extensions in which the said projections can slide axially. In such cases the chuck may make screw-threaded engagement with the end of the body portion of the device and its bore may be provided with diametrically opposed slots for receiving projections extending radially from the shaft of the bit, the upper ends of such slots communicating with an annular recess and such recess having outwardly extending but blind-ended slots. When such a chuck is fully engaged with the screwed end of the body portion the extreme end of the latter extends into the said annular recess and prevents the projections entering such recess, the procedure for securing the bit being to loosen the chuck so allowing the projection on the bit to enter the recess and the bit is then turned through a quarter turn so bringing the projections into alignment with the blind slots. The chuck is then tightened again so retaining the bit in the device but alfording it freedom for sliding movement.

In another arrangement the chuck may comprise jaws mounted for angular movement towards and away from one another, said jaws being so shaped that when in their closed position they make locking engagement with a chisel, bit or the like located therebetween, and any suitable means for retaining said jaws in their locking position or freeing them for separating movement at will.

The aforesaid jaws may be pivotally mounted in a carrier in any suitable way but I prefer so to arrange the mounting that when the jaws are in their closed position the force generated by impact or pressure applied to the bit or the like concerned is not wholly transmitted to any hinge pins or the like upon which such jaws may be mounted. Thus for instance the jaws may be provided with openings, recesses or the like for engagement with shoulders or other projections extending laterally from a carrier for said jaws, the arrangement being such that when the jaws are closed the opposed surfaces of the said cooperating openings, recesses or the like and of shoulders, projections or the like abut tightly against one another and so afford compensation for any pull or thrust applied to the bit. As an alternative to such provision or as an addition thereto the jaws may be provided with side flanges and the carrier for such jaws may be provided with recesses for pivotally receiving such side flanges, the inner faces of opposed flanges being at an angle with respect to one another when the jaws are closed and the portion of the carrier extending between such inner faces being of dovetail or other suitable contour so that longitudinal movement of the jaws with respect to the carrier in one or both directions is positively opposed so long as the jaws are maintained in their closed position. In cases where arrangements of the kind providing direct engagement between the jaws and the jaw-carrier are adopted such engagement may be of such a nature as itself to provide the required pivotal mounting without requiring any pivot pins as such.

The means employed for holding the aforesaid pivotable jaws in their closed position or releasing them at will may be of any suitable kind but I at present prefer to employ a longitudinally movable locking sleeve. Thus for instance the assembled jaws and carrier may be of round, square or hexagonal cross-section at least over their inner part and a sleeve of similar square cross-section may be mounted for sliding into a position in which opening of the jaws is prevented or into a position in which such opening is permitted at will. If desired springs or the like may be associated with such locking sleeve for urging it into its locking position, the release then necessitating the rearward movement of the sleeve against the action of the said springs or the like. Any desired locking means may also be provided for preventing inadvertent movement of the sleeve.

The carrier for the aforesaid jaws may be coupled or be adapted to be coupled to a tool body in any desired way. Thus for instance such carrier may have a rearwardly extending shaft portion adapted to be retained in the said tool body for instance by a riveting or welding operation.

If desired the aforesaid jaw-carrier may be bored for receiving a part of the chisel, bit or the like when the latter is properly located in the chuck and cases for instance where the tool is in the nature of a pick, chisel or other tool where impact is to be generated the carrier may be such that the inner end of the shaft of the bit or the like can extend completely through the chuck for (2o-operation with striking means.

In some cases it is desirable that rotation of the bit or the like about its own axis whilst in the aforesaid chuck should be positively prevented and for this purpose any suitable means may be adopted. Thus for instance in cases where the shaft of the bit or the like extends through the carrier the receiving bore in the carrier and the cross-section of the corresponding part of the shaft of the bit or the like may be hexagonal or other shape preventing relative rotation of the parts concerned.

In cases where a chuck incorporating jaws is provided the shaft of the bit or the like may be provided with a projecting collar for engagement by such jaws, the said jaws being suitable recessed for co-operation with said collar in pre-- venting longitudinal separation of the bit or the like from the jaws when the latter are closed. In cases however when the tool is of a percussive kind it is desirable that impact applied to the bit should not be transmitted through the jaws of the chuck and for that reason it is desirable that there should be slight play for floating movement of the said bit or the like. Thus for instance in cases where the shaft or the like is provided with a collar and the jaws are provided with recesses for engagement with said collar the width of the recess may be slightly greater than the width of the collar, thus ensuring that when the bit is pressed against the work it will be urged inwardly into the tool and afford freedom for slight outward movement under impact with any objectional impact being transmitted to the chuck.

Whilst the aforesaid freedom for movement of the bit is desirable when the device is used for making holes or for any other purposes for which a pick or drill may be used and where impact is applied to such bit, such movement is undesirable where for instance a device in the nature of a crow-bar, chisel or pummer is required. It is within the scope of the present invention to adapt the present device for these further uses and in cases therefore where there is provision for axial sliding of the bit I preferably also provide means whereby such movement can be prevented when desired.

The upper end of the aforesaid plunger may be provided with any suitable handle, such handle preferably being of rubber or other electrical insulating material.

If desired a resilient buffer, e. g. a rubber ring or the like, may be provided for cushioning the blow in the event of the plunger being allowed to fall from its outermost to its innermost position when no bit is fitted to the device, or when the bit is in its outermost position.

The bit or bits for use in a device according to the present invention may be of any suitable kind. Thus for instance it may have an end of conical or pyramidical shape or it may have a chisel-like cutting edge of straight, serrated or curved outline dependent upon the nature of the work for which it is intended. Moreover, such bit or the like may have an integral shaft portion for engagement by the chuck or a separate shaft portion may be adapted for making detachable connection with any required head portion, e. g. a head portion selected from a range of differing head portions.

In order that the present invention may be well understood I will now describe, by way of examples only, some specific embodiments thereof with reference to the accompanying drawings in which:

Figure 1 is a side elevation of one form of tool,

Figure 2 is a part cross-sectional broken elevation of the tool shown in Figure l but on an enlarged scale and with the chuck in the released condition and the plunger also in a released condition.

Figure 3 is a side view of the chuck locking sleeve shown in Figures 1 and 2.

Figure 4 is an end view of the sleeve shown in Figure 3.

Figure 5 is a detail view of the plunger locking sleeve shown in Figures 1 and 2.

Figure 6 is a cross-sectional view taken on the line VI-VI of Figure 5,

Figure 7 is a part sectional side elevation of another form of chuck with the jaws in the open position,

Figure 8 is a view similar to Figure 7 but showing the jaws in the closed condition,

Figure 9 is an end sectional View taken on the line IX-IX of Figure 8,

Figure 10 is a part sectional view similar to Figure 8 but turned through 90,

Figure 11 is an end sectional view on the line XI-XI of Figure 10,

Figure 12 is a part sectional side elevation showing another form of plunger locking sleeve,

Figure 13 is an end sectional view taken on the line XIII-XIII of Figure 12,

Figure 14 is a View similar to Figure 12 but showing the plunger in the released position,

Figure 15 is an end sectional elevation taken on the line XV-XV of Figure 12,

Figure 16 is part sectional side elevation showing another form of chuck,

Figure 17 is a plan view of the chuck shown in Figure 16,

Figure 18 is a part sectional side elevation of another form of chuck, and

Figure 19 is a sectional view of the chuck shown in Figure 18 but turned through 90".

Referring to Figures 1 to 6, the tool comprises a body portion consisting of a steel tube I, chuck jaws 2 and 3 pivotally mounted on a carrier se* cured to the said tube I, a chuck locking sleeve 4, a plunger 5, a handle 6 and a plunger locking sleeve 1.

The plunger 5 is a sliding t in the tube I and has a guide bush 8 fitted to its forward end, the extreme end of such plunger being' adapted upon reciprocation of the plunger to strike the adjacent end of a bit 9 held in the chuck jaws 2 and 3. The said bit may be of any shape appropriate to the work concerned and may for instance have a cranked shaft, as shown, terminating in a spade-like end.

The shaft of the bit 9 extends through the chuck for engagement by the plunger 5 and it is provided with a collar I which is engaged by recesses in the opposed faces of the chuck jaws 2 and 3 when such jaws are closed. The part of the bit which extends beyond the collar I0, is preferably of hexagonal or other suitable crosssection for co-operation with a correspondingly shaped bore in the chuck in preventing rotation 0f the said bit.

The chuck locking sleeve 4 is of square crosssection and is axially slidable on the end of the tubular body I from a position in which the jaws are permitted to open into a position in which said jaws are locked in a closed position.

Spiral springs I I, I i abut against a flange I2 extending inwardly from the sleeve 4 and against the adjustable stops in a ring I3 secured to the tubular body I for the purpose of urging the sleeve 4 in a locking direction.

The mouth of the locking sleeve 4 is belled for co-operation with the stepped outer surfaces of the chuck jaws 2 and 3 and in such a way that withdrawal of the locking sleeve through a short distance allows the said jaws to open at a wide angle and so permit of the ready insertion or removal of the bit 9.

The plunger locking sleeve 'I is of hexagonal cross-section and is axially slidable on a correspondingly shaped cap I4 fitted to the tubular body I. The said sleeve is provided with bayonet slots I5 for cooperation with lugs I6 extending from a sleeve II rotatably mounted on the plunger between a metal ring I8 and a ring I9 having a hexagonal outer periphery corresponding to the bore of the sleeve 4. When the entrances to the bayonet slots I5 are brought into alignment with the lugs I5 on the ring I'I such sleeve can move axially from a position in which it embraces the ring I9 into the position shown in Figure 5 in which it abuts against a ring 20 secured to the tubular body I, a spring 2I being provided for resiliently urging the said sleeve into the last mentioned position.

When the sleeve 'I is drawn outwardly against the action of the spring 2l into a position shrouding the ring I 9 the lugs I6 can be moved into the circumferential parts of the bayonet slots I5 by turning the ring I? and the sleeve is thus secured in a position preventing withdrawal of the plunger. The root portions of the bayonet slots may, if desired, be recessed as indicated by reference numeral 22 (see Figure 2) so that when the lugs I6 reach the ends of the slots the sleeve 'I' can move slightly outwardly under the inuence of the spring 2I and thus prevent any inadvertent movement of the ring I'I into a sleeve releasing position, i. e. it is necessary to pull the sleeve outwardly before the ring can be turned into a position bringing the lugs I6 into registration with the open ends of the bayonet slots.

As an alternative to providing recesses at the roots of the bayonet slots, or as an addition thereto, means may be provided for resiliently retaining the locking ring I'I in its locking position. Thus for instance as shown in the drawings, the ring I'I may be provided with spring urged balls 23 for co-operation with indents in the handle portion of the plunger and in such cases providing the lugs I6 are rst brought into registration with the bayonet slots by rotating the handle the rotary locking movement of the ring I'I will result in the balls 23 being forced out of one set of indents and then snapping into the second set of indents in the said handle portion and resiliently opposing any inadvertent rcleasing movement, although when release is required the ring can of course be turned providing suiiicient torque is applied to overcome the pressure of the springs acting on the balls 23.

In yet another modification of the last described embodiment the locking `lugs may be carried by the handle portion of the device and engagement and disengagement with the bayonet slots in the locking sleeve can then be elected by merely rotating the said handle.

In order to avoid objectionable impact of the handle against the cap I 4 on the tubular body portion of the device I prefer to fit a ring 24 of rubber or other resilient material on the plunger 5 immediately below the ring I 8. 1n order to prevent impact of the guide ring 8 against the cap I4 when the plunger is drawn outwardly to the limit of its outstroke a buffer spring 8 may be fitted to the plunger 5 adjacent to the ring 8.

The handle portion 6 of the plunger is preferably shrouded with a sleeve of rubber or other similar resilient and electrical insultaing material.

When the above described tool is required for use a. bit appropriate to the work concerned is inserted in the chuck, the chuck jaws being freed for separation by raising the sleeve 4 against the action of the springs I I and so allowing such f jaws to swing about their pivot pins. When the bit has been pressed inwardly as far as possible the jaws are closed over the flange I0 of the bit and the locking sleeve 4 is allowed to return to its locking position. If the tool is required for use as a crow bar it is used with the plunger locked in its innermost/position. If however the tool is required for use as a pick or the like, then the plunger is freed by moving the lugs IS into alignment with the open ends of the bayonet slots I5 whereupon the locking sleeve i is freed for downward movement until it abuts against the ring 20. The plunger can then be reciprocated in order to impart impact to the bit Q and during such action impact is applied directly to such bit and not to the chuck owing to the fact that the Chuck jaws are so shaped that when they are closed into engagement with the bit there is freedom for slight axial sliding of such bit between the position in which its ange abuts against the walls of the recesses in the chuck jaws and the position in which such flange abuts against the carrier for such jaws. When the bit is rested on the work it is of course urged into its innermost position and there is free play for it to move outwardly under impact before it could strike against the chuck jaws.

In the arrangement shown in Figures '7 to 11 the device again comprises a tubular body 25 and a bit 26 adapted to be struck by a reciprocal plunger' but the chuck and locking means differ from those already described. The chuck comprises the chuck jaws 21 and 28 pivotally mounted on a jaw carrier 29, the said carrier having a rearwardly extending tubular shaft 35 secured in the bore of the tubular body 25.

The jaw carrier 29 is provided with two recesses 3l and 32 adapted respectively to receive a bar 33 of the jaw 21 and a bar 34 of the jaw 28, the hook-like extremities 35 and 36 of the recessed part of the carrier being adapted to engage slots 31 and 38 in the jaws 21 and 28 beyond the said bars. The jaws 21 and 28 are thus anchored to the carrier 29 but are rockable from the position shown in Figure 7 into the position shown in Figure 8. In the former position the collar 39 in the shaft of the bit 25 can be passed into and from the chuck but in the latter position such collar is trapped by the surfaces 48 and 4l of the chuck jaws. The inward movement of the bit 25 is arrested by the collar 39 abutting against the adjacent edge of the carrier 29 and as shown in Figures 8 and 1G there is provision for slight axial movement of the bit when it is held in the chuck, i. e. the space between the said surfaces 4D, 4l and the end of the carrier is greater than the thickness of the flange 39.

The part of the shaft of the bit 2li extending rearwardly from the collar 39 is provided with two opposed flats and the receiving bore of the carrier 25 is of corresponding cross-section so that the said shaft is non-rotatably engaged by the carrier.

A clutch-locking sleeve 24 is slidably mounted on the aforesaid jaw carrier, such sleeve being of hexagonal cross-section for co-operation with a hexagonal flange 43 on the carrier 29. When such sleeve is moved outwardly to its limiting position, i. e. the position shown in Figures 8 and 10, it passes over stepped portions of the jaws 21 and 28 and abuts against the ends of such stepped portions, thus holding the said jaws in their closed positions. When however the sleeve is withdrawn to the position shown in Figure '7 the jaws are freed for pivotal movement into the position shown in that ligure, i. e. a position for permitting of the insertion or removal of the bit.

In order to prevent any inadvertent movement of the clutch locking sleeve 42 into a releasing position a retaining sleeve 44 is slidably mounted on the tubular body 25 and can, at will, be locked in a position in which it maintains the sleeve 42 in its jaw locking position or be freed for allowing of the release movement of such sleeve. In the arrangement shown the said retaining sleeve i4 is provided with an annular recess 45 adapted to (zo-operate with

lugs

45, 41 extending from the tubular body 25, there being slots 48 and @lil in the forward ange of the recess which permit of the passage of the retaining sleeve over the lugs when such slots and lugs are in registration. If however, the retaining sleeve is rotated into a position in which the slots are out of regstration with the lugs then the latter are trapped and a positive stop is afforded against releasing movement of the sleeve 42.

In order resiliently to locate the above mentioned retaining sleeve 44 in a position for permitting of its axial sliding movement or in a position preventing such movement spring loaded balls 58 and 5l are mounted in the sleeve for cooperation with indents in the tubular body 25. In this way any inadvertent rotation of the retaining sleeve into a position for allowing of its sliding axially is opposed.

The outward movement of the aforesaid retaining sleeve is limited by the sleeve abutting against the clutch locking sleeve 42 and its rearward movement is limited by a collar 52 tted to the tubular body 25.

Referring now to Figures l2 to 15 which show another plunger-locking arrangement, numeral 53 designates a part of the tubular body of the tool and numeral 54 designates a part of the plunger, the handle portion of the body and the handle portion of the plunger both being covered with rubber or other insulating material. A bush 55 having three projecting lugs 55 is secured to the end of the tubular body 53, for instance by means of a screw thread and a locking sleeve 51 shrouds said bush, there being three channels formed by the ribs 58 for engagement with the lugs 56 in such a way that axial sliding movement of the sleeve 51 is permitted but rotation with respect to the tubular body is prevented.

rhe sleeve 51 is provided at its outer end with an inturned flange 59 and slots are provided in such flange in registration with and of a width corresponding with the width of the channels formed by the ribs 5B, the ends of such ribs terminating at a point spaced from the said flange for a purpose hereinafter disclosed.

A bush G is xedly secured to the handle portion of the plunger 54 and has three lugs 6l spaced at for co-operation with the three slots formed in the above mentioned flange 59, the arrangement being such that when the plunger is in its innermost position, i. e. the position shown in Figure 12 the sleeve can be drawn over the bush 68, the lugs 6| passing through the slots in the flange 59. In order to permit of the sleeve being locked in this axial position the aforesaid spacing between the ends of the ribs 58 and the Opposed face of the liange 59 is such that the lugs El can pass therethrough, thus enabling the plunger 54 with the bush carried thereby to be rotated into a position in which withdrawal of the plunger is prevented by the said lugs abutting against the flange.

Compression springs 52 are located between the bush 55 and the end flange `63 of the sleeve 51 for the purpose of resiliently urging the sleeve from the position shown in Figure 12 into the position shown in Figure 14, i. e. into a position in which it abuts against a stop collar 54 tted to the tubular body 53, but it will be understood that such movement is only possible if the lugs 5| are not trapped by the flange 5S.

The inner surface of the above mentioned iiange 55 is provided with recesses 63 disposed midway between the aforesaid slots for permitting of the passage of the lugs 6l of the bush 68, the said recesses allowing for slight downward movement of the sleeve 51 when the lugs 56 are brought into registration therewith. In this way inadvertent rotation of the handle into a position in which the lugs are brought into registration with the slots in the flange 55, i. e., a position in which the plunger is freed for reciprocation, is prevented.

When however it is desired to free the plunger this can be done by pulling the sleeve 51 upwardly until the recesses G3 are out of engagement with the lugs 6l and then turning the handle until the said lugs are in registration with the slots in the fiange 59 whereupon the plunger is freed and the sleeve 51 moves under spring action to its lowermost position, i. e. the position as shown in Figure 14. In the latter position and assuming that the bit at the other end of the tool is rested on the work, i. e. that the bit is urged to its innermost position, the rubber buifer 65 is spaced slightly from the bush 55, i. e. impact is applied directly to the bit pursuant to reciprocation of the plunger. If however, the tool is raised and the plunger allowed to fall inwardly under its own weight then the impact on the said bush is cushioned by the buffer 65.

Referring now to Figures 16 and 17 the modified chuck comprises two parts E6 and 61, the part 66 being rigidly secured to the tubular body portion 66a of the tool and having an outwardly extending screw-threaded boss 68 for engagement by the screw threaded bore of the part 61 of the chuck. The part 61 is substantially of truncated conical shape merging at its inner end into a hexagon and a step is formed at said end. The

part t6 is also hexagonal in external contour, the external dimensions corresponding with those of the said step on the part 66. A sleeve `G9 of hexagonal cross-section is slidably mounted on the part 65 and is movable from the position shown in Figure 16, i. e. a position in which it engages the hexagonal step on the part -61 and thus prevents relative rotation of the latter, into a posi- 'tion in which it is wholly disposed on the part 65 and rotation of the part 51 is accordingly permitted. The said movement of the sleeve 69 may be limited by one or more projections 89a extending inwardly therefrom into an elongated recess 66h in the part 66 and I prefer to provide a spring 66e in such recess for normally urging the sleeve into the position shown in Figure 16.

The forward end of the part G1 of the chuck is provided with an inwardly directed flange 1li having a bore appropriate for receiving the shaft of the bit 1I, the flange itself being provided with two wing-

like slots

12, 12, for permitting of the axial passage of two wing-like lugs, 13, 13, projecting from the appropriate part of the shaft of the bit. Walls 14 extend inwardly from the side edges of the

slots

12, 12 and form two

recesses

15, 15 adapted to receive the said lugs 13, 13.

When it is desired to insert a bit into the chuck shown in Figures 16 and' 17 the locking sleeve 69 is retracted and the part 61 is unscrewed to an extent allowing accommodation for the lugs to pass between the end 16 of the tubular body portion of the tool and the inner ends of the walls 14. The bit is then inserted and when the lugs 13 have reached the ends of the walls 14 the bit is rotated through 90 whereupon such bit is moved outwardly from the chuck so causing the lug 13 to enter the recesses 15. The part 61 is then screwed tightly onto the part 66 whilst holding the locking sleeve in a retracted position and finally the sleeve is allowed to move back into engagement with the step in the part I(i1. It will be understood that the recesses for receiving the lugs 13, can, if desired, be of appropriate depth for allowing the bit to move axially to a small extent after the chuck has been tightened.

In the arrangement shown in Figures 18 and 19 the chuck includes two

jaws

16, 16, pivoted in openings in a head portion 11 welded or otherwise secured to the tubular body 18 of the tool, such head portion having a forward ring-like portion 19 through which the shaft Si] of the required bit can be passed, such shaft having a collar -Bl for engagement by recesses in the opposed surfaces of the jaws 16, iii. The said jaws are normally maintained in a bit-engaging position by means of a sleeve 82 but are permitted when such sleeve is retracted into a dotted position S2 shown in Figure 18, the jaws then opening into the positions shown in dotted lines and designated 1S in Figure 19. Spring loaded balls 83 engage a channel 84 in the sleeve s2 when the sleeve is in its locking position and oppose its inadvertent movement from that position. The springs associated with the said balls also serve to swing the chuck jaws into their opened positions when the sleeve is retracted.

The chuck shown in Figures 18 and 19 in addition to possessing the advantage of causing the chuck jaws to open automatically upon retracting the chuck jaws, possesses the advantage of affording front support to the bit Bil and relieving the jaws of any wear and tear pursuant to any bending movement applied to the bit itself and any resultant tendency for the jaws to become sprung apart, burred or otherwise damaged.

Whilst I have hereinbefore described some embodiments of the present invention I wish it to be understood that there may be various changes or modifications without departing from the scope of such invention. Thus for instance there may be changes in the form of the chuck as well as in the form of the chuck-locking means and/or in the plunger locking means. It is also to be understood that the tool may be of any desired shape and dimensions, it being convenient however for some purposes if the overall length of the tool is about four feet.

I claim:

1. A hand-operable percussion pick comprising a tubular body portion, a plunger reciprocably mounted within said body portion, a part extending from said plunger out of one end of said body portion and forming an actuating handle for said plunger, a hollow chuck located at the other end of said body portion and comprising two annular parts the first of which is rigidly secured to said tubular body portion and the second of which has screw-threaded engagement with the said first part, said second chuck part having an inwardly extending annular liange at its outer end and having a central opening for receiving the shank of a bit having radial projections extending from the shank, said flange having radial slots through which said radial projections may pass, and the parts of said flange located between said slots having recesses formed in the rear faces thereof in which the radial projections of the bit can be trapped upon fully inserting the bit into the chuck and then rotating it to bring the said projections into alignment with the said recesses, and said two parts of the chuck cooperating to cause partial obstruction of the entrances to said recesses when the said two parts are tightly screwed together but permitting free entry and exit of said projections when said two parts are separated by partially unscrewing of such parts, the said recesses in the iiange of said second chuck part being deeper than the radial projections on the bit thereby 'providing for limited axial movement of said bit when the latter is trapped in the chuck, the said bit being insertable into the chuck through the front of the mi@ 1A latter into a position in which the inner end of the bit is presented to receive the direct impact of said plunger, said bit also being removable from the chuck without removing any part of said chuck.

2. A hand-operable percussion pick comprising a tubular body portion, a plunger reciprocably mounted within said body portion, a part extending from said plunger out of one end of said body portion and forming an actuating handle for said plunger, a locking sleeve axially slidable on but non-rotatable with respect to said body portion and having bayonet slots therein, a collar rotatably but non-slidably mounted on said body portion adjacent to the handle portion and having lugs extending radially therefrom and disposed or engagement by said bayonet slots in said locking sleeve and permitting of said lugs being trapped in said slots or freed therefrom pursuant to rotation of said collar whereby the plunger may be trapped in its innermost position or freed for reciprocation at will, a hollow chuck located at the other end of said tubular body portion for releasably holding a bit having projections extending radially from its shank, said chuck comprising two annular parts comprising a iirst part rigidly secured to said tubular body portion and a second part having screw-threaded engagement with said rst part and is provided with a slotted bore for receiving said shank of the bit, said second part of the chuck also having recesses in which the said projections can be trapped upon fully inserting the bit and then rotating it to move the projections out of alignment with the said slots into alignment with the said recesses, the entrances to said recesses being partially obstructed when said two parts of the chuck are fully screwed together but being unobstructed when said two parts are partially unscrewed, thereby preventing or permitting the removal of the bit at will, the depth of said recesses being slightly greater than the depth of the radial projections thereby providing for limited axial movement of said bit when engaged by said chuck, and` means comprising a collar non-rotatably mounted on the rst chuck part and slidable into and out of non-rotatable engagement with the second chuck part to prevent inadvertent rotation of said second chuck part into a bit-releasing position.

3. A hand-operable percussion pick comprising a tubular body portion, a plunger reciprocably mounted within said body portion, a part extending from said plunger out of one end of said body portion and forming an actuating handle for said plunger, a hollow chuck located at the other end of said body portion and comprising two annular parts the first of which is rigidly secured to said tubular body portion and the second of which has screw-threaded engagement with the said first part, said second chuck part having an inwardly extending annular flange at its outer end and having a central opening for receiving the shank of a bit having radial projections extending from the shank, said ange having radial slots through which said radial projections may pass, and the parts of said flange located between said slots having recesses formed in the rear faces thereof in which the radial projections oi the bit can be trapped upon fully inserting the bit into the chuck and then rotating it to bring the said projections into alignment with the said recesses, and said two parts of the chuck cooperating to cause partial obstruction of the entrances to said recesses when the said two parts are tightly screwed together but permitting free entry and exit of said projections when said two parts are separated by partially unscrewing of such parts, means for preventing inadvertent rotation of said second chuck part, said means comprising a sleeve axially slidable on but non-rotatable with respect to said iirst chuck part and adapted to move into and out of interlocking engagement with said second chuck part pursuant to its axial movement along the said first chuck part, and a spring for normally moving said sleeve into said interlocking position for locking said two chuck parts against relative rotation, the said bit being insertable into the chuck through the iront of the latter into a position in which the inner end of the bit is presented to receive the direct impact of said plunger, said bit also being removable from the chuck with out removing any part of said chuck.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 348,815 Bailey Sept. 7, 1886 510,981 Massey Dec. 19, 1893 744,804 Saunders Nov. 24, 1903 925,978 Bacho et al June 22, 1999 949,796 Howard Feb. 22, 1910 1,282,928 Peirce Oct. 29, 1918 1,511,880 Gest Oct. 14, 1924 1,656,707 Hansen Jan. 17, 1928 1,800,345 Gustafson Apr. 14, 1931 FOREIGN PATENTS Number Country Date 174,217 Great Britain Jan. 26, 1922 399,663 Germany Aug, 8, 1924 525,184 Germany Apr. 30, 1931