US2847830A - Pile shells - Google Patents

Description

Aug. 19, 1958 E. A. SMITH 2,847,830

PILE SHELLS Filed June 19, 1956 5 Sheets-Sheet 1 IN VEN TOR.

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MMW @m JMM- United States Patent PILE SHELLS Edward A. Smith, Chatham, N. J., assignor to Raymond International Inc., a corporation of New Jersey Application June 19, 1956, Serial No. 592,276

11 Claims. (Cl. 61-79) This invention relates to pile driving core or mandrel constructions adapted for use within pile shells for imparting impacts from a pile driving hammer to the interior portions of the shell so as to drive the same down into the ground. More particularly, the invention relates to such mandrel or core constructions which are adapted for driving so-called straight-sided, or generally uniform diameter cylindrical pile shells.

Core constructions for driving so-called step-tapered pile shells of the type, for example, described in M. M. Upson Patent No. 1,836,140, issued December 15, 1931, have enjoyed considerable commercial success. Such core constructions are of the solid, unitary tube type-and are therefore of great ruggedness and are able to withstand severe bending stresses caused by obstructions in the ground. These core constructions, however, are usable only in the driving of that step-taper type pile, wherein the shell is by inherent design characterized by having a smaller diameter lower end than upper head. Recently some engineering authorities have been of the opinion that a large diameter pile point isdesirable in certain types of soil. However, the maximum diameter of the lower end of a step-taper pile shell is limited by economic factors, since due to the necessity of progressively increasing shell diameter, the. use of a relatively large diameter lower end results in an excessively large diameter upper head, and this means a waste of costly concrete. Attempts have, therefore, been made to provide core constructions for driving straight-sided or nontapered cyindrical pile shells. Such driving operations present difiiculties in core constructions which are not present in the step-taper pile. Namely, the use of a straight-sided pile shell imposes difiiculties in the removal of the core after driving. The pile shells which are driven in these operations are of thin or light gauge sheet metal and hence will tend to buckle inwardly during driving unless suitably reinforced from within by the core. Therefore, it is highly desirableduring driving that the clearance between the interior of the shell and the exterior of the core be held to a minimum. This driving prerequisite, in turn, of course creates a problem as regards removal of the core from the shell after driving. Heretofore in the driving of such straight-sided pile shells, various collapsible type cores have been employed, some comprising a number of elongated leaves interconnected by mechanical linkages, the leaves being adapted to be forced radially outwardly into engagement with the interior walls of the pile shell, and others comprising a plurality of elongated leaves with flexible expansion means operated by the application of internal fluid pressure to expand the leaves so as to cause their engagement with the pile shell. Such core constructions inherently possess structural weaknesses due to the multiplicity of their parts and in many instances have proven troublesome rnechanically when subjected to the severe impacts of a pile driving operation.

The present invention eliminates the above noted difficulties encountered with heretofore known expansible type cores and provides a rugged, integral tubular core construction designed to fit within a thin, generally straight-sided pile shell with only a small peripheral clearance therebetween and being readily removable from the shell after driving. The core member according to the invention comprises a rigid tube-like structure having at' regular spaced intervals along its length sets of peripherally spaced driving dogs, pivotally mounted in windows or openings formed in the core wall, in combination with a dog actuating center bar extending longitudinally through the hollow interior of the coretube with dog engaging cam means spaced therealong at intervals corresponding to the longitudinal spacing between dog sets, whereby longitudinal movement of the centerbar relative to the core tube will effect pivoting of the dogs into-or out of engagement with impact receiving means provided on the pile shell interior. With this arrangement the core may be lowered into a pile shell with its driving dogs positioned within the. outer periphery of the core tube, thereby insuring free passage ofthe core past the impact receivingmeans provided on the'interior of the pile shell. Once the core isso positioned, the center bar is arranged so as to move downwardly relativeto the core tube, thereby causing its dog engaging cam means to pivot the dogs outwardly into engagement with the impactreceiving means on the shellinterion In this position the pile maybe driven and after driving, by lifting up on the center bar, the dogs will'be cammed inwardly through the openings in the core wall to a position within the outer-periphery of the core tube, thereby freeing thecore for ready removal from the shell.

As mentioned above, pile shells contemplated foruse with the inventionwill bed the generally straight-sided or cylindrical type'and may be. ofvery light gaugemetal and may, if desired, be corrugated. Tlie=lower point of the straight-sided shell contemplated hereinmay beclosed off so as torender it watertight by means of a conventional boot plate having a diameter similar to that of the lower end of the shell. Such aboot platewould, of course, be secured to a conventional boot ring having an impact receiving surface adapted toreceive blows from a suitable driving shoulder provided on the lower end of the core. On the other hand, if desired, to the lower end of the aforedescribed straight-side'dpile shell there" may be joined a tapered lower section, forexample, of" the type described in -U. S. patent application, Serial No. 455,610, filed September 13, 1954, by Herman R; Smith, and in such event the lower'end ofthe core structurehereof would of course be fashioned as disclosed inth'at application. However, .it is also a contemplated that in certain instances it may be desirable to provide anenlarged lower point. Many attempts have heretofore been made for providing such'enlarged points, but'in none of them has the point itself been formed bya completely water tight shell capable of withstanding ground pressure after driving and permitting of inspection after the core has been withdrawn but prior to filling the shell with concrete. For the most part'such enlarged points have been formed by driving concrete out into: the ground beneath the lower end of the pile shellso as to forma bulb. Suchbulbs as mentioned, however, have not been encased by a substantially rigid and watertight 'shell. Sucha watertight shell surrounding the bulb is most desirable, since it permits of visual inspection prior to 'the pouring of the concrete, thereby insuring the driver-that a perfect pile has been driven and. can be .cas.t.=., Theapresently known enlarged points or abulbsas described above :have resulted. in imperfect piles, in t that, not. being providedl with an enclosing shell, water and mud inevitably interis mingle with the concrete before it is set, thereby reducing its load bearing capacity. The present invention also overcomes these difficulties and provides a lower end core construction which is capable of driving an enlarged shell point into the ground and also provides for ready removal of the entire core following driving.

Other and more specific objects, features and advantages of the invention will appear from the detailed description given below taken in connection with the accompanying drawings which form a part of this specification and illustrate by way of example the presently preferred embodiments of the invention.

In the drawings:

Fig. 1 is a vertical elevational view partially broken away showing the driving core of the invention with a pile shell having an enlarged lower point shelled up on the core in position ready for driving;

Fig. 2 is avertical sectional view showing the upper portion of the driving core in position within a shell;

Fig. 3 is a vertical sectional view showing the lower portion of the driving core in position within a shell;

Fig. 4 is an enlarged, fragmentary vertical sectional view showing the core dog construction with its cooperating center bar in driving position, the dogs having their driving shoulders positioned in engagement with the impact receiving means on the interior of the pile shell;

Fig. 5 is a horizontal sectional view taken on the line 5-5 of Fig. 4;

Fig. 6 is an enlarged fragmentary vertical sectional view showing a driving dog of the core being cammed inwardly out of engagement with the pile shell impact receiving ring means under the action of the center bar;

Fig. 7 is a vertical elevational view showing portions of a core assembly'according to the invention having two core units secured together by a screw threaded con nection;

Fig. 8 is an enlarged fragmentary sectional view of the screw joint for securing adjacent core units together;

Fig. 9 is a perspective showing of a lock washer used in the screw joint of Fig. 8;

Fig. 10 is a sectional view taken on the line 10-10 of Fig. 8;

Fig. 11 is an enlarged fragmentary vertical sectional view showing the expandable core tip mechanism in fully expanded driving position relative to the enlarged shell point;

Fig. 12 is a view similar to Fig. 11, but showing the core tip mechanism in partially collapsed position at the start of the removal of the core from the shell;

Fig. 13 is a view similar to Fig. 11, but showing the core tip mechanism in fully collapsed position ready for complete removal from the shell;

Fig. 14 is an enlarged horizontal sectional view of the core tip expander mechanism taken on the line 1414 of Fig. 11;

Fig. 15 is also an enlarged horizontal sectional view taken on the line 1515 of Fig. 11;

Fig. 16 is also an enlarged horizontal sectional View taken on the line 16-16 of Fig. 11;

Fig. 17 is an enlarged perspective showing of one of the expansible core tip driving leaves;

Fig. 18 is an enlarged fragmentary vertical sectional view showing one manner of securing adjacent shell sections to a driving ring; and

Fig. 19 is an enlarged fragmentary vertical sectional view showing an alternate embodiment of securing adjacent shell sections to a driving ring.

Referring now to the drawings in more detail, the core assembly of the invention comprises a head portion 20 which is adapted to receive through suitable follower pieces or the like the impacts from a pile driving hammer. The lower portion of the core head is provided with a tenon-like portion 21 adapted to be secured within a socket 22 formed in the upper end of a core head sleeve 23 by means of a cross pin 24. This core head sleeve 23 is also provided at its lower end with a socket 25 which is adapted to receive the upper end of a center bar 26, the latter being secured to the former by means of cross pin 27. It should, of course, be understood that, if desired, suitable cushioning members may be provided between the upper end of the center bar and the core head sleeve in order to absorb the shock of impact blows delivered by the pile hammer. The core tube itself may comprise an integral unit 28 having a plurality of axially aligned, spaced-apart lengths of rigid steel pipe such as 25' rigidly interconnected by tubular cast steel reinforcing collars 29. As shown, the upper and lower ends of each of these collars 29 are formed with a peripheral groove as at 30, 31 adapted to receive telescopically the adjacent end portions of the pipe sections 28 which may be then welded to the collar as at 32, 33. Each collar is provided with a plurality of peripherally spaced sidewall openings or windows 34, each designed to receive a driving dog 35. As shown the external diameter of this core is such as to permit its shelled up assembly within a pile shell 43 with only a small peripheral clearance 43' therebetween.

These cast collars 29 are formed with a thickened peripheral wall portion 36, the dog receiving windows being formed in said thickened wall portion. The design is such that even with the dog receiving window portions having been cut away, the cross-sectional area of the collar at that region is still sufficient so that the collar; possesses a strength comparable to that of the thinner walled core tube sections. Each of the windows 34 is of generally rectangular cross-section and is so dimensioned as to receive rather loosely one of the driving dogs 35. As shown, each dog is pivotally mounted in the upper end of its respective collar window, such pivotal mounting being accomplished, for example, by means of a ball and socket joint comprising a ball-like portion 37 provided on the dog and a spherical engaging socket portion 38 provided in a dog retaining bracket 39, which bracket is secured to its collar 29 by suitable means such as a head screw 40. Each of the dogs 35 is provided with a driving shoulder 41 for engaging an impact receiving driving ring 42 which is suitably secured, as for example by welding, to the interior of the pile shell 43. In order to insure even distribution of the impact blows from the pile driving hammer, the dog receiving windows of each collar are symmetrically disposed about its periphery, and each set of driving dogs will preferably comprise at least four individual dogs symmetrically disposed about the periphery of the core. In the example shown, six symmetrically disposed dogs 35 comprise a set, and-it should be, of course, understood that each set may comprise a greater number of dogs when desired, depending upon the size of the dogs and the core and the nature of the driving operations contemplated.

Pile shell 43 may be comprised of a plurality of corrugated shell sections 4-6 of the cylindrical or so-called straight sided type wherein the shell diameter remains constant throughout it length. The driving rings 42 are secured between adjacent ends of such shell sections. If desired the shell sections 46 may be rigidly joined together so as to form a one piece shell 43 prior to assembly on the core, and in this event the adjacent ends of the sections 46 may be welded rigidly to the rings 42 as shown at 42', 42 in Fig. 18. On the other hand, when it is desired that the shell be assembled on the core section by section, each shell section 46 may be welded to the top of one of the driving rings 42 as shown at 44 (Fig. 19), while to the bottom of that driving ring there is welded as at 44 a short screw collar 45 having a helical corrugation 45 adapted to threadedly engage the upper end of the next adjacent shell section 46. With such a construction additional shell sections 46 may be added to the shell by simply screwing them up over the collars 45 as needed. It will be, of course, understood that the core is provided with a set of driving dogs 35 forjeach of the driving rings 42, the exact number of such sets of dogs and cooperatingdriving rings. being dependent upon the length of shell to be. driven. The collars 29 with their sets of driving dogs may be, for example, spaced apart along the core at 8, 12, 16 or 24- ft. intervals, depending, of course, upon the intensity of driving force which will be required in the particular driving operation.

As shown in Figs. 4-6, the center bar 26extendslongitudinally through the hollow interior of the core tube and is provided with dog engaging, cam means 48 spaced along its length at intervals corresponding to the longitudinal spacing between dog sets on the core tube. Each dog engaging cam means 48 comprises a central portion 49 having a diameter greater than the diameter of the center barand a pair of oppositely inclined end portions 50;,and 51 which taper gradually from the enlarged center portion inwardly towards the center bar. Each dog 35 is ,provided with an earflike portion 52 extending angularlyinward and upward from its pivotal mounting .37, 38. Fig, 4 illustrates the relationship of the center bar dog engaging cam means and aset of driving dogs when thearespective parts are in position for driving. As there shown, the coretube is inserted imposition within cylindrical shel-l 43 and the, dogs 35 protrude outwardly beyond fthe periphery of, the core tube through their respective, windows 34 with their driving shoulders 41 engaging; the upper surface of the driving ring 42.; During dr iving the dogs are maintained in ,this outwardly projectingposition by virtue of engagement of the enlarged central portion 49 :of thecenten bar cam means being incontact with the inner surfaces. of the lower portions of thedogs as shown at53. It will be seen that when in thisdriving position the, driving force from the pile hammer is transmitted in substantially vertical, straight line direction from the core tube, to the driving rings 42 ,;there beinglittle. or no bending moment. developed in. the dogs, and thereby providing a mostdurable construction capable of withstandingsevere shocks due to driving impacts. When it is desired to remove. the core frorn the shell after the latter has been driven, the, center bar, may be raised vertically relative to its core tube as sh own in Fig. 6, thereby causing the dog cars 52 to be cammed outwardly asthey come into. engagement with theupper,taperedportion 50 of the cam engaging means 48 -,until;the enlarged center portion 49.: of this cam engagingmeans comes into contact with these ears as shown at 55, whereupon it will be observed that the dog driving shoulders. 41 have, in turn, been cammedsinwardly to such-an extentthat the, same are now positioned entirely within the inner periphery of the .core, thereby freeing the dogsand hence the core for travel past .the inwardly projecting driving rings Al positioned on the interior of theshell. With the dogs in this position, the core may be lif ted-outof its nested position in theshell and readied for use in subsequent driving operations. It will be obvious, of course, that the driving dogs may be similarly positioned within the periphery of their. core .at the time it ,is desired to shellupi (i.,e., assemble) shell sections around the driving core while, that core isrsuspended in the leadsof a pile driving hammer prior. to an actual pile, driving operation.

Intheconstructionshown the center-barmay be raised from-its drivingposition shown inFig. 4,to its removal position. as shown in Fig. 6 by simplylifting the core=head poption 20which will, in turn, raise thecorethead sleeve 23: As shown inFig. 2; there .is secured to the upper,- most, pipe section 28. of the, core tube, as by welding. at 60,:an upp er core section 61 of increased sidewall: thickness having a pair,oflongitudinallyextending slots 62 cutin its sidewalls. Secured to the core .head sleeve 23 are a pairofkey blocks 63.which.are.free to slide in these.slots.62 As shown in Fig. 2, withthe. center bar in its lower or drivingposition, an annularlshoulder 64* formed on. the corehead sleeve 1 rests on the. .top surface 6 of this upper core section 61. When, however, the core head sleeve 23 is lifted upwardly, the same, together with its connected center bar, is free to move relative to the core tube until the key blocks 63 come in contact with the shoulders 65 provided by the upper extremity of the slots 62. When these key blocks 63 engage the shoulders 65, continued upward travel of the core head sleeve will result in movement upwardly of the core tube itself. It should be understood that when the core assembly is, for example, suspended from the leads of a pile driving hammer, the. key blocks 63 will be in contact with the shoulders 65, and thus the center bar will be in its upper position as shown in Fig. 6 with the driving dogs cammed inwardly so as to permit passage of the core into the shell which is to be driven. With the parts of the core assembly in these relative positions the shell may be shelled up on the core in conventional manner, since the driving dogs are cammed inwardly and will not contact the inwardly projecting driving rings 42 on the shell interior. When the shell has been thus positioned, the winch or other mechanism holding the core suspended from the leads of the pile driver may be released sufiiciently so as to permit the core tip to move downwardly into contact with the bottom of the shell. As will be described in more detail hereinbelow, once the tip does so come into contact with the shell bottom the core tube itself will remain stationary while the core head sleeve 23 will continue to move downwardly relative to the core tube, key blocks 63 sliding in slots 62 until the shoulder 64 comes to rest on the upper core tube tube, thereby causing the dog cam engaging means 48 to force the dogs 35 laterally outward into contact with their respective shell driving rings 42. further understood that when it is desired to disassemble a dog or set of dogs 35 from the core tube, the key blocks 63 will be disengaged through the slots 62 and the center bar then raised sutficiently so as to clear the dogs completely from their cam engaging means 43, whereupon the head screws 40 can be removed and their respective.

dog retaining brackets 39 pivoted so as to permit removal of the dogs 35 through their windows 34.

As shown in Fig. 3, the lowermost core tube section 28'. is provided at its lower end with an interiorly screw.

threaded socket 65. which is adapted to receive an ex teriorly threaded stud 66, which latter as shown is formed on the upper end of a core point adapter unit 67. To the lower end of this adapter unit, there is secured by means of a socket and tenon joint with cross-pin 68 an expansible core tip mechanism 69 adapted for driving an enlarged or bulb-like shell point '70. Of course, it should be understood that it is highly desirable to pro- .vide for ready lengthening of the core tube in the event that a lengthy shell is to be driven. Therefore, as shown inFigs. 7-11, when desired, additional lengths or integral units of core tube similar in construction to unit 28 described above, having pipe sections 93 and interconnect .ing. collars 99 with driving dogs 165, may be readily secured in the screw threaded socket 655 formed in the lowermost core tube section 28 by simply providing .on the upper end of the additional unit 98 an externally threadedstud 96 which is adapted tothreadedly engage.

.the socket 65. In order to secure these core units in such' manner as to prevent relative angular displacement therebetween during driving, a lock washer 101 may be provided having opposed interior radial projections 102 slidably disposed in close fitting keyways 103 formed on the stud 96, and a pair of cutout portions 104 may be formed on the peripheral surface of the lower extremity of the socket 65. With this construction the additional length of core unit 98 may be screw threaded tightly into socket 65, whereupon by driving a cold chisel or the like under washer 101 a pair of tangs 104a may be sheared It should be ofi and simultaneously bent at right angles so as to matingly engage in the cut-out portions 104. With this construction the joint may be locked against angular displacement at exactly that point at which it becomes completely tight regardless of to What degree the stud has been screwed up into its socket. A similar lock Washer construction is, of course, also provided for preventing angular displacement between the lowermost core section and the core point adapter unit 67. It should also be understood that the length of the center bar 26 may be similarly adjusted to correspond to the length of the core tube by providing additional sections of bar secured together by means of screw joints such as 26 having similar lock washers.

As mentioned above, in certain instances it is desirable to drive a shell having an enlarged point or bulb at its lower end which is both watertight and capable of withstanding normal ground pressures after removal of the core following driving. In the embodiment shown herein such an enlarged point or bulb 79 is shown. This point may, for example, be of inverted frustro-conical shape with its upper end having a diameter substantially greater than the diameter of the pile shell 43 as shown at 71, and its lower end tapering to a diameter which may be smaller than the diameter of the pile shell as shown at 72 (Fig. 3). The lower end of this shell point is closed off by means of a circular boot plate 73 which may be welded in position as at 7 while the large diameter upper end of said point may be joined to the lower end of the shell 43 by means of a flared connecting collar 75 which may be welded in position as shown at 76, 77. It is most desirable that the point 70 be formed of light gage sheet metal and, therefore, it is necessary to provide means on the core end which will closely conform to the interior walls of this enlarged point during the driving operation so as to prevent buckling of the same under ground pressure and still will be capable of removal through the interior of the smaller diameter shell after driving. As mentioned above, to the lowermost core tube section there is secured a core point adapter unit 67, and to this adapter unit there is secured an expansible core tip mechanism 69 having an inverted frustro-conical portion 69 formed with a plurality of radially extending ribs 97 as shown best in Figs. 11-17. In the recesses or valleys thus provided on the exterior of the frustro-conical portion 69' between the ribs 97, there are formed a plurality of inwardly stepped driving shoulders 78. A plurality of downwardly tapered wedge shaped leaves 79, each having stepped shoulders 80 adapted to mate with the driving shoulders 78 on tip portion 69' are slidably secured to said tip portion by means of a pin and groove connection, with transverse pins 81 secured to the lower ends of ribs 97 being adapted for cooperation with longitudinally extending grooves 82 formed in the leaves. The lower ends of these leaves 79 are interconnected by a ring 83 which extends through suitable slots 33 formed in the lower ends of each of the leaves, the slots being closed off by retainer plates 84 welded to the bottom of each of the leaves. The diameter of the leaf positioning ring 83, will, of course, be so dimensioned so as to always maintain the lower ends of these leaves in a position which will closely conform to the lower diameter of the shell point and yet will. permit clear passage of the leaves through the interior of the shell 43.

The operation of the expandable core tip mechanism is as follows (Figs. ll-l3). Fig. 11 shows the relationship of the expansible core tip mechanism 69 to the enlarged shell point 7 when the parts are in position for driving with the core lowered fully into the shell. In this position it will be seen that the leaves 79 have been expanded outwardly into close contact with the inner wall of the shell point 70, their shoulders 80 being meshed with the driving shoulders 78 on the core tip. In this position the leaves serve to reinforce the thin gauge Wall of the sheet metal shell point and prevent collapse of the same under ground pressures during driving. When it is desired to remove the core mechanism from the shell as described above, the core head assembly will be raised upwardly, thereby first causing relative movement between the core head sleeve 23 and the core tube itself due to the sliding of key blocks 63 in slots 62. This provides initially for upward movement of the center bar 26 relative to the core with its consequent freeing of the driving dogs 35 from engagement with their driving rings 42. Once this upward movement of the core head has progressed to the point where key blocks 63 engage shoulder 65, the core tip portion 69' will, of source, be caused to move upwardly. As soon as this core tip begins to move upwardly, pins 81 will begin to slide upwardly in their respective leaf grooves 82. Continued upward movement of these pins in their grooves will, however, as shown in Fig. 12 serve to draw the upper ends of the leaves inwardly out of contact with the enlarged shell point wall until, as shown in Fig. 13, the leaves will be positioned entirely within the inner diameter of the shell 43, thereby permitting free passage of these leaves upwardly through the shell sections as the upward travel of the core is continued. This will, of course, result in leaving the enlarged shell point 70 intact in position in the ground at the lower extremity of the shell 43. In inserting the core into the shell at the start of the driving operation, the action is, of course, exactly the reverse; that is, the leaves 79 are initially suspended as shown in Fig. 14 with pins 81 engaging the upper extremity of their leaf grooves 82. As the core is lowered into position within the shell, the retainer plates 84 on each of these leaves come in contact with the boot ring 73, thereby preventing further downward movement of the leaves themselves while the core and core tip continue to move downwardly, the coaction of the pins and grooves 81, 82 serving to cam the leaves outwardly into engagement with the inner wall of the shell point until the respective parts have reached the driving position shown in Fig. 12. Once the core tip mechanism has been thus expanded into driving position as described above, further relaxation of the winch or mechanism which suspends the core mechanism in the leads of the pile driver will permit the core head sleeve 23 to move still further downward relative to the core tube, the latter remaining stationary, until the annular shoulder 64 comes to rest as shown in Fig. 2 on the top of upper core section 61. This last downward movement of the core sleeve relative to the core tube will, of course, move the center bar 26 downwardly relative to the core tube, thereby causing the driving dogs 35 to be cammed outwardly into engagement with their driving rings 42 at which point the entire mechanism will be in position for commencing the pile driving operation. It should be of course understood that the expansible core type mechanism herein disclosed may be used to drive enlarged shell points provided on the lower ends of step-tapered shells and standard tapered shells. It should be further understood that the provision of sockets such as 22 and 68 at the upper and lower ends of the straight-sided core mechanism above described makes it possible to add sections of conventional step-taper core either at the top or at the lower end of the straight-sided core section, the same being connected by conventional tenon and cross-pin means, when it is desired to drive a composite pile having either or both upper and lower ends formed of the step-taper type with the central portion being formed of the straightsided type. Furthermore, it should be understood that the straight-sided core section above described can also be used to drive a composite pile using a pipe, H-beam or a wood pile as the lower section with the upper section being of the straight-sided shell type.

Although certain particular embodiments of the invention are herein disclosed for purposes of explanation,

various further modifications, thereof,- after study, of;

this specification, will be apparent to those skilled in the art to which this in ventiomper tains. Reference should accordingly .be had to, the appendedclaims in determining face, and a rigid tubular core positioned within said, shell and. dimensioned so, as to provide only a slight peripheral clearance between itself and the shell whereby the core will; serve to, reinforce the shell during driving and yet will permit of,slidablelremoval therefrom subsequent to driving, said core having mounted therein at spaced longitudinal intervals sets of driving dogs, the dogs of-each set-being-symmetricallyspaced about the core periphery, each of said dogs being pivotally mounted in a window in the core, in combination with actuating means extending longitudinally through the interior of the core and having dog cam engaging means spaced therealong at intervals corresponding to the longitudinal spacing between dog sets on the core whereby longitudinal movement of the actuating means relative to the core tube will pivot the dogs into and out of engagement with said impact receiving means provided on the shell, said shell having secured thereto at its lower end a watertight point section of generally frustro-conical form and having a portion of enlarged cross-sectional diameter and an expansible core tip mechanism provided on the lower end of said core and having means for expanding said mechanism into contact with the said enlarged shell point during driving and for collapsing said mechanism subsequent to driving so as to permit read removal thereof through the interior of the smaller diameter shell.

2. A driving core and pile shell assembly comprising a generally cylindrical light-gauge metal shell having internally projecting'driving means positioned along its interior surface and a rigid tubular core positioned within said shell and dimensioned so as to provide only a slight peripheral clearance between itself and the shell whereby the core will serve to reinforce the shell during driving and yet will permit of slidable removal therefrom subsequent to driving, said core having mounted therein at spaced longitudinal intervals sets of dogs symmetrically spaced about its periphery, each of said dogs being pivotally mounted in a window in the core and center bar means extending longitudinally through the interior of the core and having dog cam engaging means spaced therealong at intervals corresponding to the longitudinal spacing between dog sets on the core whereby longitudinal movement of the center bar relative to the core tube will pivot the dogs from a position within the periphery of the core into engagement with the said driving means provided on the shell.

3. A driving core and pile shell assembly comprising a sheet metal shell and a core positioned within said shell and dimensioned so as to provide only a slight peripheral clearance between itself and the shell whereby the core will serve to reinforce the shell during driving and yet will permit of slidable removal therefrom subsequent to driving, said shell having secured thereto at its lower end a watertight point section of enlarged cross-sectional diameter and an expansible core type mechanism provided on the lower end of said core and having means for expanding said mechanism into contact with the said enlarged shell point during driving and for collapsing said mechanism subsequent to driving so as to permit ready removal thereof through the interior of the smaller diameter shell.

4. A driving core and pile shell assembly comprising a generally cylindrical, light-gauge metal shell having inrna ly, r i g ns imn sw ei ng meansp s tion d 11 its interior surface and a rigid, non-collapsible, unitary, tube-like core positioned within said she'll-and dimension ed so asto. provide-only ,a slight peripheral clearance 1 between itself andgthe rshell whereby the core will serve to reinforce the r shell; duringdriving and yet will permit of slidable removal therefrom subsequent to driving,; sa1d;" core having mounted -therein a set of driving dogs, said dogs ,being symmetrically spaced about the core periph ery, eachof saiddogsbeing, pivotally mounted in a win dow inthe core and means ,to cam said dogs from a posi v tion entirely within the outertperipheryof the coreout wardly into engagement with the, said"irnpact receiving means provided on thewshell.

5. A core assern bly for driving pile shellsof the ,genegally straight-sided, type tcomprising a plurality of axially aligned, rigid,pipe, sections, the adjacent-ends of saidsec: tions nsj i id y emannested by bul r in tzrs si collars, each said collars being formed ,with a th ened peripheral wall portion having a plurality of dIlV- ing dog receiving openings formed therein and symmetrically spaced about the periphery thereof, driving dogs pivotally mounted in the upper end of each of the collar openings, said dogs being provided with an ear-like portion extending inward and upward from the dogs point of pivotal mounting with the core and a center bar dog actuating means extending longitudinally through the interior of the said rigid pipe sections and collars and being provided with dog engaging cam means adapted to engage the ear-like portion of said dogs for pivoting the dogs inwardly through their openings to a position within the outer periphery of their respective collars when it is desired to insert or remove the core assembly in a pile shell.

6. A driving core and pile shell assembly comprising a light-gauge metal shell and a core positioned within said shell, said shell having secured thereto at its lower end a substantially watertight point section of generally frustro-conical form having a portion of enlarged diameter relative to the shell diameter and an expansible core tip mechanism provided on the lower end. of said core and having means for expanding said mechanism into contact with the said enlarged shell point during driving and for collapsing said mechanism subsequent to driving so as to permit ready removal thereof through the interior of the smaller diameter shell.

7. A driving core and pile shell assembly comprising a shell and a core positioned within said shell, said shell having secured thereto at its lower end an enlarged, generally frustro-conical point section formed of light-gauge sheet metal and an expansible core tip mechanism provided on the lower end of said core and comprising a plurality of driving leaves with means for expanding said leaves into contact with the said enlarged shell point during driving and for collapsing said leaves subsequent to driving so as to permit ready removal thereof through the interior of the smaller diameter shell.

8. A core assembly for driving pile shells of the type having an enlarged point section comprising a tubular core having an expansible core tip mechanism secured to its lower end, said core tip mechanism comprising a portion having a plurality of inwardly stepped driving shoulders, a plurality of driving leaves secured] by pin and groove connections to said portion, the leaves having a plurality of stepped shoulders adapted to mate with the driving shoulders on said portion when the tip mechanism is in expanded condition ready for driving.

9. A core assembly for driving pile shells of the type having an enlarged point section, having an expansible core tip mechanism secured to its lower end, said core tip mechanism comprising a portion having a plurality of inwardly stepped driving shoulders, a plurality of driving leaves secured by pin and groove connections to said frustro-conical portion and having a plurality of 11 stepped shoulders adapted to mate with the driving shoulders on said portion.

10. A driving core and pile shell assembly comprising a light-gauge sheet metal shell and a rigid, noncollapsible, unitary tube-like core positioned within said shell and capable of being removed therefrom after driving, said shell having secured thereto at its lower end an enlarged bulbous section formed of material capable of withstanding ground pressure after removal of the core and an expansible core tip mechanism provided on the lower end of said core and having means for expanding said mechanism into contact with the said enlarged shell point during driving and for collapsing said mechanism subsequent to driving so as to permit ready removal through the interior of the smaller diameter shell.

1'1. A core assembly for driving pile shells of the generally straight-sided type comprising a plurality of axially aligned rigid core tube units, the adjacent ends of said units being secured together so as to prevent angular displacement therebetween during driving and a set of driving dogs provided in each unit, the dogs of each set i being symmetrically spaced about the periphery of the core unit with each dog being pivotally mounted in an opening formed in the wall of its core tube unit, said dogs being provided with means extending inwardly into the interior of the core and dog actuating means positioned within said interior of the core for engaging said inwardly projecting means on the dogs whereby relative longitudinal movement between the dog actuating means and the core will cause the said dogs to be cammed from a position entirely within the periphery of the core to a position extending outwardly of the core periphery.

References Cited in the file of this patent UNITED STATES PATENTS

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