US2677343A - Anchor - Google Patents

Description

May 4, 1954 H. P. SHIPLEY ANCHOR Original Filed Feb. 5, 1950 FIG. I. 22 E i 4 Sheets-Sheet l INVENTOR HA RDWICK I? SH/PLEY ATTORNEY y 4, 1954 H. P. SHIPLEY 2,677,343

ANCHOR Original Filed Feb. 5, 1950 4 SheetsSheet 2 INVENT OR HA ROW/6K P SH/PLEY ATTORNEY May 4, 1954 H. P. SHIPLEY 2,677,343

ANCHOR Original Filed Feb. 3, 1950 4 Sheets-Sheet 5 INVENTOR nARowlax' F! SHIPLEY ATTORNEY y 4, 1954 H. P. SHIPLEY 2,677,343

ANCHOR Original Filed Feb. 5, 1950 4 Sheets-Sheet 4 n a o '0 u .0 9 E 5 8 AREA OF GROWN OPENING PROJECTED AREA OF PLATE ELEMENT (m THousANn Las) m -2 m: o

N w w g g, q t q INVENTOR i HARDWIOK P. SHIPLEY o m m 0 o qn N BY SClNVSflOl-U. m 3.LV'ld umouo vauv iuanow ATTORNEY WEIGHT OF ANOHORUN THOUSAND LBS) Patented May 4, 1954 NlTED STATES TENT OFFICE Continuation of abandoned application Serial No. 142,243, February 3, 1950. This application June 17, 1953, Serial No. 362,429

(Granted under Title 35, U. S. Code (1952),

see. 266) 17 Claims.

This application is a continuation of application Serial No. 142,243, filed February 3, 1956, which has since become abandoned and, which in turn is a continuation-in-part of application Serial No. 531,239, filed April 15, 1944, for an Anchor, now Patent No. 2,496,315.

lhe invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

The present invention relates to anchors and more specifically to anchors of a novel construction so as to be applicable to both large and small ships.

In prior known anchors, of the type which possess flukes rotatable a limited number of degrees with respect to the shank, the tendency has been toward broad, fiat fiukes which, by presenting a wide surface normal to the direction of pull on the anchor, increase the holding power of the device. The use of such wide surfaces, however, has a serious disadvantage in the fact that many times the anchor has to be pulled a considerable distance before the fiukes take hold of the ground. When the anchor is dropped, the wide fiukes often fall flat on the surface of the ground so that when force is applied to the anchor the flukes skid along the surface of the ground rather than bury themselves. The skidding will often continue until the flu-hes strike some obstruction to rotate them into the ground. Also other types of prior art anchors have employed a large mass of metal for the crown and utilized only relatively short, narrow flul-zes so that the holding ability of the device is supplied primarily through the sheer weight of the metal. However, this type is likewise unsatisfactory since it is burdensome to handle and store, it adds unnecessary weight to the vessel using it, and it does not function eficiently.

The anchor relating to the present invention, on the other hand, offers many improvements over prior anchors and thereby eliminates the digging-in function prior to the gripping of the nukes, which makes it operative immediately upon being dropped, and it exhibits a holding power which is greater than comparable anchors of the older types. By means of the novel construction of the crown, and its associated digging element in the present invention, the flukes are assisted in quickl burying into the ground and are then maintained at their optimum operating angle thereby providing desirable features which are not shown in prior anchors.

An object of the present invention is the provision of an anchor which has a positive diggingin function prior to the gripping of the fiukes.

Another object is to provide an anchor which has a digging element for rotating the fiukes to an initial gripping position.

Another object is to provide an anchor having a crown which will pass substantially all of the earth dislodged and which will not clog up.

A further object is the provision of an anchor having a digging element which assists the fiukes to assume the optimum position for holding.

Still another object is the provision of an anchor which exhibits a high holding power for its weight and size.

Yet another object is to provide an anchor having a scoop-shaped digging element and. a stool; on the crown end of the anchor to limit the depth to which the crown will be imbedded.

A further object is to provide an anchor of a type described, comprising an elongated stock which not only acts as a stabilizer for preventing rotation or tumbling of the anchor, but also insures that the anchor, when dropped, will assume a digging-in position so that it will immediately start to dig in when pulled upon.

A primary object of the invention is to provide an anchor of a type described having a crown, dukes and rear stock which co-operate to cause the anchor substantially immediately upon reaching ground, hard or soft, to start to dig into the ground and before it is dragged a distance approximating its own length.

A final object is to provide an anchor having a digging element which prevents the anchor 3 from inadvertently breaking free, and a stock which prevents the anchor from burying too deeply.

A further object of the invention is to provide an anchor which rapidly begins its digging-in function once it is dropped, and which exhibits an outstanding holding power for its weight when it is imbedded in the ground but without any significant tendency to keep digging deeper into the ground.

Other objects and features of the invention will become apparent to those skilled in the art as the disclosure is made in the following detailed description of a preferred embodiment of the invention as illustrated in the accompanying sheet of drawings, on different scales, in which Fig. 1 is a plan view, partly in section, of the preferred anchor with its flukes closed.

Fig. 2 is a side view of the anchor with its flukes fully open and showing the crown in cross-section.

Fig. 3 is an after end view of the crown showing the space for passage of earth dislodged by the digging element.

Fig. 4 is a perspective View of the anchor more clearly showing the crown structure.

Fig. 5 is a view representing the digging or plate element as an area projected on a plane normal to the plane of the flukes; representative values of such areas for specific anchors being indicated in a table set forth in the specification.

Fig. 6 is a perspective view showing that the flukes will dig into the ground even with the anchor on its side.

Fig. '7 is a graphical representation generally corresponding to certain values of typical anchors set forth in the aforesaid table, the curve thereof having as ordinates the ratio of areas of dirtdischarge openings of crowns to the projected areas of digging or plate elements, and having as abscissae the weights of the associated anchors.

Fig. 8 is a graphical representation generally corresponding to certain values of typical anchors set forth in the aforesaid table, the curve thereof having as ordinates the moments area of digging or plate elements of the crown, and having as abscissae the weights of the associate anchors.

Referring now to the drawings, wherein like reference characters designate like or corresponding parts throughout the several views, there is shown in Fig. 1 a general view of the present invention comprising an anchor having a pair of flukes 2|, a shank 22, a stock 23, and a crown 24. At the extreme forward end of shank 22 there is pivotally mounted a shackle 25 for attachment to a cable, chain, or the like, from a vessel, while the rear or after end of the shank extends into, and is completely surrounded by, crown 2 3. The after end extremity of the shank is provided with an aperture 21 whereby the shank is freely mounted upon the stock 23 so that it is able to oscillate about the stock, independently of the crown. Hence, the center part of the stock 23 acts as a pivot shaft.

The stock 23 consists of an elongated member which is always positioned normal to the longitudinal axis of shank 22, and passes through the shank and crown 24. Associated with the stock 23, and forming an integral portion thereof, is an abutment 28 which cooperates with a washer 2B and pin 3|) to hold crown 24 in position on the stock, but at the same time permitting the crown to freely oscillate on the stock.

As is clearly apparent from the drawings, each of the flukes 2| comprises a comparatively extensive or fiat portion which is relatively wide at its after end and tapers to an edge in the form of a point or tip at its forward end so as to permit the fluke to freely enter and to dig into the ground when force is applied to the anchor to pull it forward. In the embodiment described, the broad or fiat portions of the flukes 2| can be considered to lie in a single central plane that is common to and passes through both of them. The flukes may be provided with reinforcing ridges such as better shown in Fig. 6, these ridges extending along the shank-side edges of the flat portions of the flukes.

When the flukes are in the ground in an operating position such as shown in Fig. 2, their flat portions in the ground provide a drag that opposes the pull on the anchor and in this manner produce the desired holding power. The flukes 2|, at their after ends, are attached to and form an integral part of the crown 2 whereby they oscillate about the shaft 23 along with the crown, there being one fluke positioned on each side of the shank 22.

The crown 24 comprises two side pieces, or webs 3i, positioned parallel with shank 22 and located on either side thereof so as to form a support for flukes 2i. Connecting the two side pieces SI and extending normal to their planes are digging members or plate elements or members 32 which are positioned so as to be inclined with said central plane of the flukes 2!. Also connecting the side pieces, on the side opposite the flukes, is a cross-piece 33. The digging elements 32 consist of fiat plates positioned so as to define a dihedral angle of substantially 30 to and preferably about 60, and since the plates are positioned equidistantly on either side of flukes 2|, then each plate makes an angle of from 15 to 40 and preferably about 30 relative to said flukes. It is evident that the plates slope outwardly and forwardly with respect to the flukes; that is, the plates are positioned at a slope making a forwardly flaring angle relative to the fiukes, as is apparent in Fig. 2. These plates may be sharpened along their forward edges 34 to facilitate digging in, while their interior surfaces 35, as limited by the side pieces 3 l, form digging surfaces which function to enter the ground prior to the flukes 2 l. The area of these digging surfaces may be clearly seen in Figs. 4 and 5, and the manner in which they function will be described more fully hereinafter. It can be observed from Fig. 2, that the digging surfaces are more extensive than the digging edges 34.

As can be clearly seen in the views of Figs. 2 and 3, digging elements 32 do not extend completely to close the crown 24, but when taken in cooperation with the side pieces 3 i, define a specific passageway 36, through the crown, between the shank and the digging elements of an area to permit any ground dislodged by the digging elements to pass therethrough. The dimensions of passageway 36 relative to the other elements of the anchor will be more fully described hereinafter.

Within the crown 24 and integral with shank 22 and extending on either side thereof, but spaced away from the side webs, are protuberances 38 which function to contact the inner surface 35 of the digging elements thereby to act as a limit-stop for the crown and flukes as they rotate about stock 23. The height of the protuberances is such that, when one of the digging elements seats thereagainst, that digging element is parallel to the longitudinal axis of the shank and the other element 32 is at an angle in the range of about 30 to 80", but preferably about 60, with the shank, and the angle between the longitudinal axis of the shank and the fiukes is between 20 and 40 but preferably 30.

The operation of the present invention is typically as follows:

A sume that the anchor is deposited upon the ground or sea bed and that at this stage rests upon the tips of the flukes 2| and the forward edge 34 of the digging element, with the shank 22 extending at an angle somewhat above the fiukes depending upon the amount of cable attached to the anchor. The flukes are at a slight angle with the ground (about but havent necessarily started to dig in. The stock serves generally to force the anchor substantially to this position when the anchor is first dropped and pulled.

As a forward force is imparted to the anchor, the digging element 32 which is in contact with the ground immediately starts to dig in, even before the flukes 2| take hold, inasmuch as the digging element is at quite a sharp angle with the ground. As penetration of the ground by the digging element proceeds, the reaction of the ground on this element creates a torque on the crown and attached nukes tending to rotate the ilulees, about the stock, acting as a pivot, downward into the ground. After this initial engagement of the flukes has been accomplished, the torque developed by the action of the ground on element 32 combines with the torque due to the downward component of the ground force on the flakes and assists in rotating the flukes into their final operative angular position of approximately 39 with the center-line of the shank, such as seen in Fig. 2. As is apparent from Fig. 2, this angular position of the flukes is obtained with the fiukes sloping outwardly and forwardly relative to the shank; that is, the flukes in this position are at a slope making a forwardly flaring angle relative to the shank. One protuberance 38 abuts the digging element 32 which is not in the ground, so that when the flukes are completely open they are at the optimum angle for penetration and holding power.

Any forward motion of the anchor, which might result from the application of force thereto, will cause a strip of ground to be dislodged by the digging element, but the passageway 36, through the crown, is so proportioned that the dislodged ground will freely and unobstructedly pass therethrough. By preventing the crown from clogging up, the desired rotating torque imparted to the flukes is not destroyed.

In order that all of the earth dislodged may pass through passageway 36, this opening is designed to bear a definite relation to the size of digging elements 32 and the angle with which they are positioned relative to flukes 2|. This relation varies with different sized anchors, and is illustrated in Fig. 2 wherein is shown the foremosu and rearmost edges of the digging element 32 projected onto a plane perpendicular to the plane of the flukes. For the anchor of Fig. 2, it will be found that the distance measured along the perpendicular plane, between the projections of these edges, is less than the narrowest part of the passageway through the crown. In other words the projected distance 81, for the anchors as shown in Figs. 2 and 5, is less than the distance from the rearmost edge of element 32 to the nearest portion of the shank. This last distance is indicated as the dimension 36' in Fig. 2. The relationship of this distance 36' to the projection distance 31 for anchors of various weights constructed in accordance with the principles of this invention is shown in a table subsequently set forth in columns 1 and 4.

It is obvious that the amount of earth dislodged by the digging element is directly proportional to the projected area of the digging surface (Fig. 5). As the anchor is varied in weight for application to ships of different sizes, then this projected area should also vary in size; and in order to insure free movement of the dislodged earth through the crown, it is necessary that the area of the opening 36 vary proportionately. Experience has shown, however, that as the weight of the anchor increases, the accompanying increase in area of the opening may be somewhat lessened relatively and the graph of Fig. 7 shows the trend of this relationship. In the graph the ratio of the area of the opening to the projected area of the plate element is plotted against weight of the anchor and it can be seen that the curve falls off at first and then from about 10,000 lbs. up it practically levels off to a straight line. The equation for the curve of Fig. '7 may be stated as In an anchor of the type described, the torque which the digging elements exert to rotate the fiukes downward into the ground may be expressed in familiar engineering language as the moment of the digging element about the crown pivot point, or in other words the projected area of the digging element times the moment arm. The graph of Fig. 3, which is a plot of the mo ment of digging element (crown plate) against weight of the anchor, shows that this relationship goes up in a straight line as the size of the anchor increases, and the curve may be expressed as y:0.3386w+27.5005.

The following table has been compiled to better illustrate the relationship between the various elements which make up the present invention, and the manner in which these elements vary as the size of the anchor varies. The headings of the various columns may be more fully described as follows:

0. Weight of the anchor in pounds.

1. Height of the opening (36) in inches.

2. Width of the opening (35) in inches.

3. Area of the opening (35) in square inches (columns 1x2).

4. Projected height of digging plate (see 3?, Figs. 2 and 5).

5. Width of plate (same as column 2).

6. Projected area of digging plate (Fig. 5) (columns 4x5).

7. Ratio of area of opening to projected area of the plate (column 3/6).

8. Lever arm of plate element (from plane of flukes).

9. Moment area of plate element (columns 6X8) 10. Ratio of the area of opening to the moment area of the plate element (column 3/9).

11. Ratio of the moment area of the plate element to the area of the opening (column 9/3).

12. Ratio of height of opening to the projected height of the plate element (column l/ l).

13. Logm of weight in pounds.

Ht. Width Area Proj Moment Anchor Open- Open- Open- Proj. g Area B31110 {if Area Rfltlo B3110 B8410 E"? Wt. ing ing ing Ht. P1 P1 P1. 2 in Lbs. at at at P]. as 2 Element 6 Elem'ent Element 9 3 4 Lb Rem Rear Rear 4X5 6X8 It is obvious that curves may be plotted from the data given in the foregoing table and a comparison of the features of the present invention made thereby. The plot of Fig. 7 was made from the data of column '7, while Fig. 8 is from column 9, both curves, however, being extended out beyond the limits shown in the table.

In addition to assisting the flukes to rotate into the ground, the digging elements 32 serve several added purposes. It will be noted in Fig. 2 that the element which is not engaging the ground abuts the protuberance 33 when the flukes are fully open and also that protuberance 38 is constructed of such a length that the element 32 maintains a position substantially parallel with shank 22. In this manner there is effectively produced a safety feature to prevent the anchor from freeing itself, should it bury itself below the level of the stock. If, by some circumstance the anchor should penetrate the ground until the upper digging element also engages the ground, then any ground disturbed by this upper element will pass directly through the crown without irn-- parting any rotation to the flukes, since the plane of the digging element is parallel with the motion of the anchor. It can be clearly seen that if the upper digging element did not come to rest substantially parallel to the shank and the direction of applied force, that any rotation which it would apply to the flukes would be either counter to the ground engaging rotation of the opposite digging element, thereby tending to break the flukes out of the ground, or else the rotation would be so as to make the flukes dig even deeper, both of which are undesirable. It will be noted that the upper digging element will not roll up the dislodged earth, nor clog up, to impart a counter rotation to the flukes, even through the protuberance 38 is in contact with the upper digging element, because there is still sufficient clearance on either side of the protuberance to pass the earth.

The stock 23, of the present invention, is made comparatively long, relative to the width of the flakes, and thereby serves several distinct purposes. First, that the anchor will always ultimately position itself with its flukes parallel with the ground, even though it should primarily hit the ground in a position such as shown in Fig. 6. It can be seen in that view that the three points of contact are so spaced, and the center of gravity of the anchor is so off balance, that the anchor cannot remain in this position, and so will fall over and dig in. Another purpose served by the relatively long stock is that it functions to prevent the anchor from burying itself too deeply into the ground. Once the flukes have started to engage the ground, they will continue to penetrate until a point is reached where the stock is flush with the level of the ground. The comparatively long stock will not readily sink into the ground, and by distributing over a wide area the force tending to bury the anchor, the continued penetration is effectively halted. If an anchor be permitted to continue penetration until some hard obstruction is hit below the ground, it would be so firmly imbedded that its removal would be impossible without damage to the flukes or shank. The present anchor is designed to offer maximum holding power when its flukes are fully open and it is buried to the center line of the shank.

A common failing of prior art anchors which have no crown stock, is that should one fluke strike an obstruction in the ground, the anchor becomes unbalanced and thereafter will tumble, or rotate, and ultimately will pull out of the ground. The long stock on the present anchor in addition to its other advantages will obviate this difiioulty and maintain the device balanced at all times.

Fig. 6 clearly illustrates another advantage of the preesnt invention in respect to the shape of the forward portion of the flukes, and it can be seen that the tapering, pointed flukes always present a point, positioned for penetration into the ground, even though the anchor should fall, as shown.

From the foregoing description, the advantages of the present anchor over those of the prior art may be summarized as follows. Where the anchor crown is provided with a stock but has no positive digging elements as in certain wellknown anchors, the flukes are not forcibly engaged by the ground during setting of the anchor and such anchors have been known to skid on hard ground for a considerable period before engaging their flukes. Furthermore, once the flukes engage, the crown continues to move along the surface of the ground thereby permitting the angle of attack of the flukes to increase whereby the anchor continues to bore into the ground to great depths and forcing the relatively thin, sharp shank,- to plow into the ground. This has the overwhelming disadvantage of making it impossible to withdraw the anchor without bending or damaging, or even destroying, the flukes and the shank. Such anchors, even when provided with a crown stock, have been known to enter into hard ground a distance of twenty-five feet and to have been rendered completely useless by the forces applied thereto during their subsequent removal.

Where an anchor is provided with digging elements but no stock on its crown, the digging elements will cause the flukes to forcibly engage the ground during setting of the anchor to provide rapid imbedding of the flukes but because the digging elements must always be designed to have a greater angle of attack than the flukes to be effective, the digging elements will burrow into the ground more rapidly and deeply than the flukes to cause the flukes eventually to assume an angle which will bring them up out of the ground thereby rendering the anchor inoperative.

It is apparent, then, that by providing both digging elements and a stock on the crown of the anchor as in the present invention, these disadvantages of the prior art are obviated. The present anchor causes rapid setting of the flukes and prevents the shank from plowing into the ground and eliminates the tendency of the digging elements to bore too deeply once the stock engages the surface of the ground, the digging elements having too small an area to drag the stock down below the surface of the ground. As the angle of attack of the flukes on the ground is not permitted to increase on full digging in of the crown, there is no tendency of the anchor to bore rapidly downward to undesirable depths even though the anchor may drag due to excessive winds blowing on the anchored vessel. This allows the anchor to be retrieved with ease and without damage.

Because the plate of the upper digging element assumes a position parallel to the longitudinal of the shank during setting of the anchor, there is no tendency, when the anchor is being set in mud, for the upper digging element to exert a counter-torque acting to force the flukes out of contact with the ground, and the fact that the protuberance on the shank is spaced from the webs of the digging elements, prevents mud from balling up in the upper digging element to produce such a counter-torque.

It should be understood, of course, that the foregoing disclosure relates to only a preferred embodiment of the invention and that numerous modifications or alterations may be made therein without departing from the spirit and the scope of the invention as set forth in the appended claims.

What is claimed is:

1. An anchor comprising a shank and a crown, said crown having a air of flukes pivotally mounted on the shank for rotation, said. crown including webs, and a substantially rectangular plate element supported by said webs, said plate element having substantially parallel interior and exterior flat surfaces, said plate element having a forward end adapted to dig into the ground and rock the crown relative to the shank so as to rotate the flukes downward into the ground, said plate element being positioned at a slope making a forwardly flaring angle relative to said flukes, said plate element having its rearward end spaced away from the nearest portion of the shank by a distance greater than the difference in distance between the projections of the said forward and rearward ends on a plane perpendicu- 10 lar to the plane of the flukes, and a protuberance on said shank to contact the interior flat surface of said plate element and thereby limit move-- ment of the crown relative to the shank.

2. An anchor comprising a shank and a crown, Said crown having a pair of flukes pivotally mounted on the shank for rotation, said crown including webs, a substantially rectangular plate element supported by said webs, said plate element having substantially parallel interior and exterior flat surfaces, said plate element adapted to dig into the ground at its forward end and rock the crown relative to the shank so as to 1'0 tate the flukes downward into the ground, said plate element being positioned at a forwardly flaring angle relative to said flukes, said plate element having its rearward end spaced away from the nearest portion of the shank by a distance greater than the difference in distance between the projections of the said forward and rearward ends on a plane perpendicular to the plane of the flukes, and a protuberance on said shank extending at right angles thereto, said protuberance arranged to contact the interior flat surface of said plate element and thereby limit movement of the crown relative to the shank.

3. An anchor of a type described comprising, in combination, a shank and a crown enveloping one end of said shank, a pivotal connection joining said shank and said crown, said crown having a pair of substantially fiat flukes extending forwardly thereof each having a side edge that is wide rearwardly and tapers inwardly forwardly substantially to a tip, said crown comprising a pair of spaced webs, said webs being on opposite sides of said shank, said crown comprising a plate element between said webs, said plate element having a forwardly facing interior digging surface inclined to the central plane of the flukes, said digging surface being substantially fiat and having a sharp forward edge extending forwardly of said webs, said plate element having a rearward edge spaced from the shank but closer the central plane of the flukes than its forward edge, and said plate element being adapted to dig into the ground and rock the crown relative to the shank so as to rotate the flukes downward into the ground, said plate element having its rearward end spaced away from the nearest portion of the shank by a distance greater than the difference in distance between the projections of said forward and rearward edges on a plane perpendicular to the plane of the flukes, and an elongated stock extending outwardly from both sides of said crown so that said anchor when cle posited on the ground can rest upon the tips of said flukes and on said forward edge of said plate element.

4. An anchor of a type described comprising, in combination, a shank and a crown enveloping one end of said shank, a pivotal connection joining said shank and said crown, said crown having a pair of substantially flat flukes extending forwardly thereof each having a side edge that is wide rearwardly and tapers inwardly forwardly substantially to a tip, said crown comprising a pair of spaced webs, said webs being on opposite sides of said shank, said crown comprising plate elements between said webs, each of said plate elements having a forwardly facing interior dig ging surface inclined to the central plane of the flukes, said digging surface being substantially flat and having a sharp forward edge extending forwardly of said webs, each of said plate elements having a rearward edge spaced from the shank but closer the central plane of the flukes than its forward edge, each of said plate elements being adapted to dig into the ground and rock the crown relative to the shank so as to rotate the flukes downward into the ground, each of said plate elements having its rearward end spaced away from the nearest portion of the shank by a distance greater than the difference in distance between the projections of said forward and rearward edges on a plane perpendicular to the plane of the flukes, a projecting element on said shank adjacent said crown for engaging said crown and thereby constituting stop means, and stock means extending outwardly beyond said flukes.

5. An anchor as defined in claim 4 but further characterized by said plate element comprising an exterior flat surface substantially parallel to said interior surface, and forming an angle of about 15 to 40 with said flukes.

6. An anchor of a type described comprising, in combination: a shank in the form of a straight bar, said bar having a shackle means at its forward end and an after end, a unitary open-ended crown comprising a web on each side of said after end of said shank, said crown also comprising digging members joining said webs and lying on opposite sides of said shank, said crown further comprising flukes extending from said webs, said flukes having broad flat portions, said digging members comprising flat elements at a slope making a forwardly flaring angle about 15 to 40 with respect to the axis of said shank when said flukes extend parallel to said axis of said shank, a pivot connection between said shank and crown, whereby said shank and crown are separately oscillatable on said connection, said flukes having side edges with portions that taper inwardly forwardly substantially to a tip, and a relatively elongated stock means extending from both sides of said crown beyond said flukes.

'7. An anchor as defined in claim 6 but further characterized by a projecting element on each of a pair of sides of said shank adjacent said pivot connection generally intermediate said flat elements, each projecting element having a face for bearing against an adjacent flat element.

8. An anchor of a type described comprising, in combination: a shank in the form of a straight bar, said bar having a shackle means at its forward end and a single aperture in its after end, a unitary open-ended crown comprising a web on each side of said after end of said shank, each web having an aperture, said crown also comprising digging members joining said webs and lying on opposite sides of said shank, said digging members'having sharp forward edges, said crown further comprising flukes extending from said webs, said flukes having broad flat portions, said digging members comprising flat elements at a slope making a forwardly flaring angle about 15 to 40 to the axis of said shank when said flukes extend parallel to said axis of said shank, the rear size of the opening of said crown being on account of said sloping elements less than but over one-half that of the forward opening of said crown, and a relatively elongated stock journalled in said aperture and said apertures in said webs, whereby said shank and crown are separately oscillatable on said stock, each of said flukes having a tapered forward edge portion coming substantially to a tip.

9. An anchor as defined in claim 8 but further characterized by a narrow cross piece joining the rear edges of said webs, paralleling said stock,

10. An anchor as defined in claim 8 but further characterized by said forward edges of said digging elements extending forwardly of said webs.

11. An anchor of a type described comprising, in combination: a shank in the form of a straight bar, said bar having a shackle means at its forward end and a single aperture in its after end, a unitary open-ended crown comprising a web on each side of said after end of said shank, each web having an aperture, said crown also comprising digging members joining said webs and lying on opposite sides of said shank, said digging members having sharp forward edges, said crown further comprising flukes extending from said webs, said flukes having broad flat portions, said digging members comprising flat elements at a slope making a forwardly flaring angle about 15 to 40 with respect to the axis of said shank when said flukes extend parallel to said axis of said shank, the area of the rear opening of said crown being on account of said sloping elements less than but over one-half that of the forward opening of said crown, and stop means on said shank adjacent the crown adapted to engage said crown for limiting tilting of said crown beyond a position where one of said digging members is substantially parallel to said shank.

12. An anchor as defined in claim 11 but further characterized by said stop means being protuberances on said shank in line with said openings in said crown but narrower than said openings so as not to bar the movement of ground through said openings.

13. An anchor comprising a shank, an open crown at one end of said shank, a pivotal connection joining said shank and said crown, a pair of flukes secured to and extending forwardly of said crown, said flukes having a forward digging end, said crown comprising web means and a pair of digging elements supported by said web means so that each element generally makes a forwardly flaring acute angle relative to said flukes, each digging element having an interior surface facing toward said shank and a sharp forward end adapted to dig into the ground and rock the crown and flukes relative to the shank so as to rotate said flukes downward into the ground whereby they can dig into the ground, each digging element having its rearward end closer to said shank than its said forward end but spaced from said shank so that dirt dug up by said digging elements can pass through the space therebetween, an elongated stock means extending outwardly from both sides of said crown beyond said flukes, a pair of protuberances extending from a pair of sides of said shank adjacent said crown for engaging the interior surfaces of said digging elements, said protuberances being of lengths to engage a first of said digging elements to restrain the other of said digging elements at a slope making a forwardly flaring acute angle with respect to said shank, the sum of said acute angles being less than ninety degrees.

14. An anchor of a type described comprising in combination a shank having a forward end provided with a shackle means and having an after end, a unitary open-ended crown pivoted to said shank at said after end, said crown comprising a pair of similar digging members spaced from said shank on opposite sides thereof whereby dirt is adapted to pass between said members, said web means extending to and between said digging members, said digging members having substantially parallel forward digging edges and rearward surface portions that are more extensive than said digging edges and extend from said edges to the rear of said crown, a pair of flukes secured to and extending forwardly of said crown, said fiukes having broad portions lying substantially in a plane making a forwardly flaring acute angle with respect to said surface portions of said digging members, each of said fiukes having a side edge with a forward portion that tapers substantially to a tip, and a relatively elongated stock means extending from both sides of said crown and beyond said fiukes.

15. An anchor of a type described comprising in combination a shank having a forward end provided with a shackle means and having an after end, a unitary open-ended crown pivoted to said shank at said after end, said crown comprising a pair of similar digging members spaced from said shank on opposite sides thereof whereby dirt is adapted to pass between said members, and web means extending to and between said digging members, said digging members having substantially parallel forward digging edges and rearward surface portions that are more extensive than said digging edges and extend from said edges to the rear of said crown, a pair of fiukes secured to and extending forwardly of said crown, said fiukes having broad portions lying substantially in a plane making a forwardly flaring acute angle with respect to said surface portions of said digging members, each of said fiukes having a side edge with a forward portion that tapers substantially to a tip, a relatively elongated stock means extending from both sides of said crown and beyond said iiukes, and stop means comprising a portion on each side of said shank, each of said stop portions having a face for bearing against a co-operative portion on said crown for limiting pivoting movement of said crown to a position wherein the maximum movement of said surface portions is to positions substantially parallel to said shank.

16. An anchor comprising a shank, an open crown at one end of said shank, a pivotal connection joining said shank and said crown, a pair of flukes secured to and extending forwardly of said crown, said flukes having a forward digging end, said crown comprising web means and a pair of diggin elements supported by said web means so that each element generally makes a forwardly fiaring acute angle relative to said fiukes, each digging element having a sharp forward end adapted to dig into the ground and rock the crown and fiukes relative to the shank so as to rotate said flukes downward into the ground whereby they can dig into the ground, each digging element having its rearward end closer to said shank than its said forward end but spaced from said shank so that dirt dug up by said digging elements can pass through the space therebetween, an elongated stock means extending outwardly from both sides of said crown beyond said flukes, and stop means at said crown for engaging a first of said digging elements to restrain the other of said digging elements at a forwardly flaring acute angle with respect to said shank, the sum of said acute angles being less than ninety degrees.

17. An anchor of a type described comprising, in combination, a shank having a forward end provided with a shackle means and having an after end, said shank having an open crown and a pair of fiukes pivoted thereto at said after end, said crown comprisin a pair of digging elements spaced from said shank on opposite sides thereof and providing open passage means in the space between said digging elements for the passage of dirt therethrough, said pair of flukes having broad portions lying substantially in a plane making a forwardly flaring acute angle with respect to each of said digging elements, stock means extending laterally outwardly of said crown on both sides thereof and beyond said broad portions of said fiukes, said stock means being substantially parallel to said plane, and stop means for limiting pivoting movement of said crown and flukes to a position wherein said plane makes a forwardly flaring acute angle with respect to said shank, the sum of the last said acute angle and each one of the first said acute angles being less than degrees.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 308,646 Williams Dec. 2, 1884 314,149 Pettes Mar. 17, 1885 439,921 Williams Nov. 4, 1890 532,606 Sproat Jan. 15, 1895 913,367 Downie Feb. 23, 1909 1,497,693 Myers June 17, 1924 2,249,546 Danforth July 15, 1941 FOREIGN PATENTS Number Country Date 261,980 Great Britain Dec. 2, 1926 610,779 Germany Mar. 22, 1935

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