Abstract:
A connection for firmly securing an adapter for carrying a digging tooth to a lip of an excavating container. The connection has substantially aligned openings in the adapter and the lip. A pressure applying unit, such as a hydraulic actuator, is arranged inside the opening and generates a generally horizontally acting force which draws the adapter and the lip towards each other. A stress member is operatively coupled to the hydraulic actuator and resiliently deforms relative to its relaxed shape when it is subjected to the horizontally acting force. The wedge is shaped so that upon a reduction or cessation of the horizontally acting force the stress member, remains in the resiliently deformed state in which it draws the adapter and the lip towards each other and keeps them immovably secured to each other until the wedge can be withdrawn following a repressurization of the hydraulic actuator.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application is a Continuation-in-Part of allowed U.S. patent application Ser. No. 12/881,997 filed Sep. 14, 2010, which claims the benefit of U.S. Provisional Application No. 61/276,786, filed Sep. 15, 2009, the entire contents of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     Ground-moving and excavating equipment employs shovels, buckets and the like with which earth, gravel, rock formation and the like are excavated and moved around. Typically, such buckets carry a lip along their digging edges, and the lips in turn mount the digging teeth. 
     The digging teeth and their connections to the lips of the buckets are subject to the most wear and tear of the entire bucket because they are exposed to constant abrasion, impacts and the like. As a result, they require frequent replacement. Replacing the teeth in accordance with the prior art is relatively time-consuming, and the excavating equipment must sit idle during that time, which is undesirable because it ultimately reduces profits. 
     There are presently many variations of how the teeth are attached to the adapters and the adapters are in turn attached to the lips of the buckets or shovels. U.S. Pat. Nos. 4,413,432, 6,032,390, 6,216,368 and 6,668,472, for example, disclose different approaches for securing teeth to the adapters and/or the adapters to the lip. 
     The present invention is particularly directed to the manner in which the adapters are secured to the lips or other members of a wide variety of containers used in ground-handling equipment, such as loaders, shovels, buckets, dragline buckets and the like. 
     BRIEF SUMMARY OF THE INVENTION 
     Generally speaking, the present invention secures an adapter to the front edge of a container or bucket, or a lip carried by the container and digging teeth to a front end of the adapter or the front edge of the container. A connection is provided for firmly securing replaceable digging teeth to either the front edge of the container, or to the adapter, and the adapter to the lip of an excavating container of excavating equipment, such as, for example, a loader, a shovel, a dragline bucket or the like. 
     The adapter has an upper leg and a lower leg located proximate respective upper and lower surfaces of the lip. The connection employs substantially aligned openings in the legs and the lip, and engagement sections of the adapter legs traverse the opening in the lip proximate and forward of an aft end thereof. A pressure applying unit is arranged inside the openings and generates a generally horizontally acting force which draws the adapter and the lip towards each other. A stress member is operatively coupled to the pressure applying unit and resiliently deforms relative to its relaxed shape when the stress member is subjected to the horizontally acting force. Further, a spacer is inserted between the pressure applying unit and the openings while the horizontally acting force resiliently deforms the stress member. The spacer is shaped so that upon a reduction or cessation of the horizontally acting force the spacer continues to maintain the stress member in a resiliently deformed state in which the adapter and the lip are locked to each other. 
     In one embodiment of the invention, generally oblong, vertically oriented, aligned slots are provided in the adapter with a similarly vertically oriented slot in the bucket or lip (hereafter usually referred to as “lip”). The stress member is formed by a C-clamp with a main body from which a pair of arms perpendicularly extend. The C-clamp is inserted into the aligned holes formed by the adapter and the lip so that the arms of the clamp engage generally rearwardly extending, typically inclined, ramps defined by an aft section of the adapter. 
     The forward facing side of the main body of the C-clamp is flat and vertical. The clamp is further constructed so that the rearwardly facing side of the main body is spaced apart from the adjacent hole wall in the adapter through which the C-clamp extends. 
     A pressure applying unit in the form of a hydraulic actuator with at least one and preferably a plurality of, e.g. two, hydraulically actuated pistons is inserted into the aligned holes so that the pistons face the vertical, forward facing or front side of the main C-clamp body. The front side of the pressure applying unit extends in a vertical direction past the end of the hole in the lip and is supported by and positioned on the lip proximate the forward end thereof. 
     The rearwardly facing or aft surface of the pressure applying unit, past which the pistons can be extended, and which faces the vertical front side of the main C-clamp body, is angularly inclined relative to the vertical and diverges in a downward direction relative thereto. As a result, following placement of the C-clamp and the pressure applying unit into the substantially aligned holes in the lip and the adapter, a downwardly converging, wedge-shaped space is formed between the inclined aft surface of the pressure applying unit and the vertical front side of the C-clamp. 
     The spacer, in the form of a wedge, has a flat, vertical rearwardly facing aft surface that mates with the vertical front side of the C-clamp. The opposite front side of the wedge forms a serrated surface that is complementary to the correspondingly serrated aft surface of the pressure applying unit. The serrated front surface of the wedge is angularly inclined relative to its flat aft surface and converges in a downward direction to define the wedge, which is shaped so that it substantially corresponds to the wedge-shaped space between the front side of the C-clamp and the aft side of the pressure applying unit. 
     The wedge is fork-shaped, and the portion thereof overlying the piston or pistons in the pressure applying unit remains open so that the pistons can be moved rearwardly from the pressure applying unit into engagement with the vertical front side of the C-clamp. 
     In use, after the C-clamp and the pressure applying unit have been slipped over and engage the adapter and the lip, respectively, the wedge is inserted into the wedge-shaped space between the C-clamp and the pressure applying unit. 
     To secure the adapter to the lip, the hydraulic actuators are energized to move the pistons rearwardly into engagement with the vertical front side of the C-clamp. As the pressure in the hydraulic actuators increases by applying as much as 10,000 psi, which, in a presently preferred embodiment of the invention, generates a force of about 50 tons, the main body of the C-clamp is deflected in the aft direction. This in turn resiliently stresses the C-clamp and spreads its arms apart, which increases the spacing between them so that the force applied by the pistons forces the C-clamp in the aft direction relative to the adapter engaged by the C-clamp arms. 
     The applied force also elongates the holes in the lip and the adapter, which also causes some resilient elongation of the length of the openings in the adapter. 
     As a result of the foregoing, the downwardly converging space between the C-clamp body and the pressure applying unit becomes larger in a generally horizontal direction and allows the wedge to further drop downwardly into that space. 
     When the hydraulic pressure in the actuator which defines the pressure applying unit is relieved, the built-up stresses in the resiliently deflected C-clamp push the actuator via the wedge forwardly into rigid engagement with the lip, while the resiliently deflected arms of the C-clamp remain in forced engagement with the adapter since the wedge remains fixed between the C-clamp and the pressure applying unit. The interlocking serrations of the pressure applying unit and the wedge prevent the latter from moving upwardly out of the wedge-shaped space between the pressure applying unit and the C-clamp. 
     Although it is preferred that the vertical aft side of the C-clamp remains spaced apart from the proximate aft wall of the opening in the adapter, it is possible to use the arrangement without such spacing. In such an event, the C-clamp is locked in place and instead of the C-clamp being resiliently stressed, the metal of the adapter and the lip become tension-stressed in the horizontal direction to open up the wedge-shaped space between the C-clamp and the hydraulic actuator. When the pressure on the pistons of the actuator is relieved, the stressed portions of the adapter and the lip move a slight distance back towards their relaxed state until the wedge between the C-clamp and the hydraulic actuator blocks further contractions by the lip and the adapter, thereby locking the wedge in place and maintaining the stress-induced force, which tends to move the lip and the adapter towards each other. 
     Another embodiment of the present invention is particularly well-adapted for use with dragline buckets of dragline excavating equipment. Thus, this embodiment provides a connection for firmly securing the adapter for detachably carrying a replaceable digging tooth at its front end to the lip of an excavating container, e.g. a dragline bucket. The connection has substantially aligned openings in the legs and the lip, and engagement sections of the adapter legs traverse the opening in the lip proximate and forward of the aft end of the opening. The upper and lower legs of the adapter extend from proximate a front end of the lip at inclined angles relative to the respective upper and lower surfaces of the lip. As a result, the opening in the lip and the openings in the adapter legs are non-contiguous. A pressure applying unit, again preferably a hydraulic actuator, is arranged inside the openings and configured to selectively apply and release a generally horizontally acting force which draws the adapter and the lip towards each other. A wedge is arranged in the openings, converges in a vertical, typically downward, direction, and is disposed between and in contact with an inclined side of the hydraulic actuator, preferably its front side, and the vertical front wall of the opening in the lip, which together define a wedge-shaped space that receives the wedge. 
     The hydraulic actuator has at least one power-actuated piston that is extendable and retractable in a generally horizontal direction through the wedge-shaped space for applying the generally horizontally acting force to the upper and lower legs of the adapter. This enlarges a horizontal extent of the wedge-shaped space and resiliently elongates the upper and lower adapter legs, which places the legs in a stressed state. The wedge placed in the wedge-shaped space has a horizontal dimension selected so that when it is inserted into the wedge-shaped space while the hydraulic actuator applies the horizontally acting force, the adapter legs are and remain in their stressed state even if the pressure acting in the pistons is reduced or ceases altogether as generally described above, thereby maintaining the lip and the adapter in firm, immovable contact with each other. 
     As stated, the pressure applying unit will normally be a hydraulic actuator, and it preferably comprises a housing that extends through at least a portion of the openings in the adapter and the lip in a generally vertical direction. The housing defines an interior cavity inside of which at least one and preferably two hydraulic pistons are movable in a generally horizontal direction for placing the stress member in its stressed state. A pressure conduit extends from the cavity to a vertical end, preferably the upper end, of the housing for pressurizing and depressurizing the cavity, which extends the pistons out of and retracts them into the cavity. A pressure fitting adapted to be connected to a source of a pressurized fluid communicates with the conduit and extends to an exterior of the housing, where a metal cap covers the vertical (e.g. upper) end of the housing to encapsulate the pressure fitting and protect it from debris and against heavy impacts which might damage the fitting and render it inoperative. The cap is removably secured to the housing, preferably with at least one detent member in either the housing or the cap and a depression cooperating with the detent member in the other one of the housing and the cap. The detent member is spring-biased into the depression when the cap is placed over the vertical end of the housing and retains the cap on the housing with a force selected so that the cap can be manually removed from the housing to provide access to the pressure fitting. 
     To enable removal of the protective cap in the event it became damaged in use and can no longer be manually removed, the housing preferably includes a generally horizontally oriented support surface proximate the vertical (e.g. upper) end of the housing. The cap extends in a vertical direction past this support surface and defines a cut-out positioned proximate the support surface and shaped to be engaged by a prying tool that is configured to rest on the support surface while it engages the cut-out so that the cap, when jammed, can be pried off the housing with a suitable prying tool. 
     According to a further embodiment of the invention the digging tooth is immovably secured to a front end of an excavating container or bucket. The front end, which can be the front end of the bucket or an adapter interposed between the bucket and the tooth (hereafter sometimes collectively also referred to as the “adapter”), has upwardly and downwardly facing surfaces that converge in a forward direction. The tooth has upper and lower legs that face the respective upper and lower surfaces of the front end. An opening through the adapter and openings through the legs of the tooth overlap and the tooth has engagement sections that traverse the opening in the adapter. 
     A pressure applying unit, preferably a hydraulic actuator, is located in the overlapping openings in the adapter and the legs, engages the engagement sections of the tooth legs, and selectively generates and releases a horizontally acting force which draws the tooth and the adapter towards each other. The tooth legs resiliently deform relative to their relaxed shape when subjected to the horizontally acting force. A wedge is inserted between the hydraulic actuator, the opening in the adapter and the tooth openings while the horizontally acting force resiliently deforms the stress member. The wedge is shaped and dimensioned so that upon a reduction or cessation of the horizontally acting force the tooth legs remain stressed. 
     The tooth is immovably but detachably secured to the front end of a bucket or an adapter by positioning the tooth over the front end of the adapter and bracing a body of the tooth from which its legs extend against relatively moving in an aft direction. When the horizontal force is applied while bracing the body in this manner the tooth legs are elastically elongated in the aft direction, thereby subjecting the legs to tension stresses. 
     To facilitate bracing the body it converges in a forward direction where it forms the tip of the tooth. The rear end of the body includes a rearwardly facing aft surface which has a shape that conforms to that of the front end of the bucket so that the aft surface of the body fully abuts against the front end of the bucket in a stable manner. 
     When the horizontally acting force is released the elongated legs are prevented from returning to their unstressed state because they continue to be subjected to the residual horizontal force. Thus, the legs remain in a residual stressed state and continue to generate a residual horizontal force. The tooth including particularly its legs are shaped and dimensioned so that in their residually stressed state the residual horizontal force generated by the legs of the tooth is sufficient to immovably secure the tooth to adapter. As a result, the tooth remains immovably fixed to the adapter (or the container lip) even though the actuator which initially generated the horizontal force remains deenergized during normal operations of the excavation equipment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  schematically illustrates an excavating unit to which an excavating bucket having a front lip, an adapter overlying the lip and digging teeth are secured; 
         FIG. 2  is a side elevational view, in section, showing the hydraulic lock of the present invention; 
         FIG. 3  is an exploded, perspective view separately illustrating the components of the hydraulic lock shown in  FIG. 2 ; 
         FIG. 4  is a perspective, exploded view of a hydraulic actuator and a serrated face thereon employed by the present invention; 
         FIG. 5  is a perspective view of the hydraulic actuator in its assembled state; 
         FIG. 6  is a perspective view of a piston employed in the hydraulic actuator shown in  FIG. 5 ; 
         FIG. 7  is a perspective, side elevational view, in section, similar to  FIG. 2  and illustrates an alternative embodiment of the present invention; 
         FIG. 8  is a plan view, in section, and is taken on line  8 - 8  of  FIG. 7 ; 
         FIG. 9  is a side elevational view, in section, and illustrates an alternative embodiment of the present invention that is particularly suitable for use on dragline buckets; 
         FIG. 10  is a partial sectional view of a releasable connection of a digging tooth to an adapter or a container lip in accordance with the present invention; 
         FIG. 11  is an exploded, perspective view of the tooth connection shown in  FIG. 10 , and 
         FIG. 12  is a fragmentary schematic plan view in the direction of arrows  12 - 12  of the portion of  FIG. 10  showing the force applying unit illustrated in  FIG. 10 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 1 , by way of background, a bucket, shovel or the like  2  (hereafter sometimes also more generally referred to as “container”) is conventionally attached to a piece of excavating equipment  4 . A front lip  6  is normally separately attached in any one of a variety of manners to the bucket, but which can also be formed by the bucket itself should that be desired. The lip defines a front edge  8  of the bucket. Digging teeth  10  are spaced apart across the width of the bucket and project from the lip in the forward, travel direction of the excavating equipment. An adapter  12  is interposed between each tooth and the bucket lip. Each adapter has a front end to which the tooth is typically replaceably attached and an aft portion  14  defined by upper and lower legs  16 ,  18 , respectively, which overlie respective upper and lower surfaces  20 ,  22  of the bucket lip and can be slipped onto the lip. 
     The bucket teeth are subject to heavy wear and rough treatment and therefore require frequent replacement. The adapters holding the teeth are also subject to heavy wear and rough treatment and therefore also require frequent replacement. To allow replacement of the adapter, it is releasably secured to the bucket lip  6  by a connection  24  (not shown in  FIG. 1 ) constructed in accordance with the present invention as is described below. 
     A widely used connection of this type is the so-called Whistler connection that employs a C-clamp which extends through aligned openings in the legs  16 ,  18  of the adapter and lip  6 . By applying a horizontal, rearwardly directed force against the C-clamp, its arms press the adapter against the upper and lower surfaces of the lip and thereby lock the two to each other. To prevent a loosening of the lock, a variety of releasable locking devices are used that in one manner or another employ wedged surfaces that maintain the C-clamp in engagement and lock it in place to prevent the clamp from becoming loose. 
     Keeping down-time of the excavating equipment to a minimum, prior art connections employed locking members that could normally be reasonably quickly released to allow the replacement of the worn adapter. However, in the course of replacement those parts of the connection became damaged and had to be replaced at significant cost. 
     Referring now to  FIGS. 2 and 3 , in one preferred embodiment, a connection  24  constructed in accordance with the present invention positions the upper and lower legs of the adapter over lip  6  so that respective vertical openings  26  and  28  in the lip and the legs of the adapter overlie each other. As is well-known in the art and illustrated in the drawing figures, the aft and front ends  30 ,  32  of the vertical openings in the adapter are located forward of the aft and front ends  34 ,  36  of the hole in the lip when the front edge  8  of the lip engages the adapter while maintaining an open passage extending through both openings through which the components of connection  24  are inserted as described in the following. 
     A C-clamp  38  has a main body  40  that extends through the openings in the adapter legs and the lip and a pair of arms  42  that extend rearwardly from the main body. Engagement surfaces  44  are defined by surfaces of the arms that face each other, diverge in an aft direction and form a taper relative to the horizontal in the aft direction. A vertical end of the C-clamp is preferably provided with a handlebar  46 . 
     With the C-clamp in its relaxed, unstressed state, it is moved rearwardly so that the opposing engagement surfaces  44  on the arms of the C-clamp engage a preferably slightly rounded edge  48  of the aft portion of the adapter at a point spaced from respective forward and aft ends of engagement surfaces  44 . Edge  48  is generally defined by the intersection of aft surface  30  of the hole in the adapter and a tapered surface  50  of the adapter surface. The latter preferably has substantially the same angle of inclination relative to the horizontal as the engagement surfaces on the C-clamp arms. 
     A pressure applying unit  52  is next inserted into the holes extending through the adapter and the lip between a vertical, front surface  54  of the C-clamp and front surface  36  of hole  26  in the lip. 
     Referring now to  FIGS. 2 ,  4  and  5 , pressure applying unit  52  is preferably a hydraulic actuator that has a main body  58  that defines a front surface  56  which is in abutment with front surface  36  of hole  26  in the lip and an aft surface  60  formed in part by the main body and in part by a plate  62  with undulations  64  that extend in a horizontal direction across the width of the plate and form smooth, alternating ridges  66  and valleys  68 . Screws  70  releasably secure plate  62  to main body  58 . The portion  61  of aft surface  60  defined by the main body  58  is recessed relative to the undulations in plate  62  and smooth, that is, free of undulations, as best seen in  FIG. 5 . 
     Front surface  56  of the hydraulic actuator is vertically oriented parallel to the front surface  36  in lip opening  26 , while aft surface  60  converges at an angle to the vertical towards front surface  54  of C-clamp  38  in a downward direction to define a wedge-shaped space  57  between the two that converges in a downward direction. 
     On its inside, body  58  forms a pair of spaced-apart cylinder openings  72  that movably houses a disc-shaped flange  74  of a hydraulic piston  76 . Each flange includes an O-ring  78  to seal the piston as it reciprocates inside the cylindrical opening. A tension spring  80  has an inner hook  82  that is anchored to a bolt  84  that extends across the cylindrical opening formed in a depression  86  extending from the closed end of the cylindrical opening as is illustrated in  FIG. 2 . 
     Pushers  88 , which are an integral part of piston  76 , preferably have a generally rectangular cross-section and extend from piston flanges  74  in the aft direction through openings  90  in plate  62  with sufficient play so that the pushers can reciprocate through the openings. 
     Hydraulic actuator  52  further includes a high pressure fitting  92  that is in fluid communication with the interior of cylinder openings  72 . When high pressure hydraulic fluid is applied to the fitting via a suitable pressure hose (not shown) connected to a source of high pressure, presently preferably capable of applying a pressure of at least 10,000 psi, pistons  76  move against the tension force exerted by springs  80  in the aft direction so that pushers  88  move past the openings  90  in plate  62  towards front side  54  of the C-clamp. Conversely, by reducing or ceasing entirely the pressure applied to the interior of cylindrical openings  72 , the tension of springs  80  retracts the pistons so that the ends of pushers  88  project only slightly, or not at all, out of openings  90  in the plate. 
     Hydraulic actuator  52  is inserted into the approximately aligned openings  26 ,  28  through the lip and the adapter, and the front surface  56  of the actuator abuts the front surface  36  of the hole through the lip. Flanges  94 ,  96  at upper and lower ends of actuator body or housing  58  center the actuator relative to opening  26  through the lip. Hydraulic pressure is then applied via fitting  92  into the interior of cylinders  72  to push pistons  76  rearwardly until force transmission surfaces  98  at the ends of pushers  88  engage front surface  54  of the C-clamp and in particular that section of main C-clamp body  40  which is inside hole  26  through the lip. 
     In a presently preferred embodiment of the invention, adapted for use with connections for a wide variety of sizes of bucket lips, adapters and C-clamps, the hydraulic cylinders are dimensioned so that the two pistons  76  exert a combined force of about 50 tons against the aft side of the C-clamp. This force deflects the main body of the most commonly used C-clamps rearwardly, which in turn causes arms  42  of the C-clamp to spread apart, thereby increasing the spacing between them and causing the pushers  88  of the pistons to move the C-clamp in an aft direction relative to the tapered surface  50  at the aft portion of adapters  12 . 
     With the pistons moved rearwardly as far as possible under the applied force generated by the hydraulic pressure in the cylinders, a forked wedge  100  is dropped into the wedge-shaped space  57  between the forward surface  54  of the C-clamp and aft surface  60  of hydraulic actuator  52 . 
     As is best seen in  FIGS. 2 and 3 , the wedge has a width about equal to the width of hydraulic actuator body  58  and is defined by a pair of spaced-apart legs  102  which, at their upper ends, are joined by a top section  104  of the wedge. The open space between the legs is greater than the width, as measured in the horizontal direction, of pushers  88  so that the legs straddle the pushers and the latter can extend rearwardly in the horizontal direction past the thickness of the C-clamp. 
     An aft surface  106  of the wedge is flat, while a front surface  108  thereof is inclined relative to the vertical and converges relative to the aft surface of the wedge in a downward direction. It is further dimensioned so that the wedge can be dropped into the wedge-shaped space  57  between aft surface  60  of the hydraulic actuator and front surface  54  of the C-clamp. Further, the front surface of the wedge has horizontally extending undulations or serrations  110  which correspond to the undulations  64  in actuator plate  62 . The thickness of the wedge is such that it can be dropped into the wedge-shaped space  57  when the pistons are under pressure and so that the wedge will not permit the C-clamp to return to its unstressed, relaxed state when pressure in the hydraulic actuator is reduced or ceases. 
     With pistons  76  in actuator  52  energized, wedge  100  is dropped into the space between the hydraulic actuator and the front surface of the C-clamp as far as possible, preferably by manually pushing the top  104  of the wedge downwardly as far as possible until it comes to rest at a location relative to the actuator where the undulating surfaces of the wedge and the actuator are in engagement, that is, where the ridges of one engage the valleys of the other. The relative dimensions of the opposing, undulating surfaces are selected relative to the maximum rearward deflection of the main C-clamp body while pressure is applied to the hydraulic cylinders so that, upon the release of the pressure, the deflected main body of the C-clamp can, at the most, return over only a small proportion of its total deflection back towards its relaxed state before its arms firmly engage and are prevented from further movement in the forward direction by the hydraulic actuator housing  58  and wedge  100  interposed between them. The wedge thereby becomes locked in position by the interengaged undulations on the hydraulic actuator and the wedge and is prevented from vertically moving inside the hole through the lip and the adapter legs. 
     Following the completion of the connection  24  in the just-described manner, a protective, resilient cap, e.g. made of rubber or the like (not shown), can be placed over the free end of pressure fitting  92 . It is additionally preferred to place a metal cover (not shown in  FIGS. 2-6 ) over the open space  112  at the upper end of actuator  52 . 
     When it is time to replace a worn adapter  12  with a new one, the just-described metal cap and/or rubber cover are removed from the top of fitting  92 , a pressure hose is connected to the fitting, and the hydraulic cylinders are pressurized to move pistons  76  rearwardly and deflect the main body  40  of the C-clamp in the aft direction as aforedescribed in connection with the installation of a new clamp onto the lip. This deflection of the main body in the aft direction enlarges the wedge-shaped space  57  between the opposing surfaces of the actuator and the clamp to its original, maximum extent. The wedge is thereby loosened so that the opposing undulations on the wedge and the actuator become disengaged. This permits the wedge to be manually pulled out of the wedge-shaped space  57 . 
     This opening of connection  24  is rapidly accomplished by simply applying pressure to the actuator and causes no damage to the C-clamp, the wedge or the hydraulic actuator because all relative movements between the three parts are conducted while the energized pistons  74  keep the wedge-shaped space  57  sufficiently wide to permit sliding the wedge in and out of the opening without requiring hammer blows, crunching turning movements of a screw or the like between any two or more of these parts. 
     Thus, while the initial cost of the connection, and in particular of the pressure applying unit, e.g. including the hydraulic actuators, is greater than the initial costs of many prior art connections, the much greater speed with which the connection of the present invention can be set and released greatly reduces the excavation equipment down-time required for replacing adapters on container lips, which in and of itself provides significant cost savings. Additional, significant cost savings result from the reusability of the three principal components that form the connection. 
     Referring now to  FIGS. 7 and 8 , in an alternative embodiment of the present invention there are no horizontal undulations between the pressure applying unit, e.g. of hydraulic actuator  52 , and wedge  100 . In this embodiment, horizontal undulations  114 , which correspond to serrations  64  shown in  FIGS. 2-6 , are formed on front surface  54  of C-clamp  38  and the side of wedge  100  facing it, as illustrated in  FIG. 7 . Front surface  54  of the C-clamp and the matching surface of the wedge are vertically oriented. A front surface  116  of wedge  100  tapers in a downward direction relative to its side facing front surface  54  of the C-clamp, and the wedge is disposed in a wedge-shaped space defined by the front surface of the C-clamp and a downwardly converging but otherwise flat surface  118  of the hydraulic unit. 
     To secure the connection  24  shown in  FIG. 7 , C-clamp  38  is inserted in openings  26 ,  28  as earlier described so that its arms  42  contact engagement surfaces  44  of the adapter. The hydraulic actuator is positioned at the front end of the overlapping holes  26 ,  28  in the lip and the adapter, and wedge  100  is inserted in the wedge-shaped space (not separately numbered in  FIG. 7 ) between front surface  54  of the C-clamp and the aft, tapered surface  118  of the hydraulic actuator. The wedge is placed so that its serrations  114  face the corresponding serrations on the front surface  54  of the C-clamp. 
     Thereafter a hydraulic pressure conduit, such as a hose (not shown), is connected to pressure fitting  92 , and pistons  76  of the hydraulic actuator are energized to move them in a horizontally aft direction until they engage the main body of the C-clamp and prestress it as was described earlier, thereby resiliently deforming the C-clamp, which enables it to be further pushed in an aft direction onto the sloping engagement surfaces  50  of the adapter. While the pistons are energized, wedge  100  is manually pushed down into the enlarged wedge-shaped space between the front surface of the C-clamp and the hydraulic actuator and, thereafter, the pressure on the hydraulic pistons is released. Upon release of the pressure, the resiliently deformed C-clamp returns a short distance towards its relaxed condition but remains locked in place by wedge  100  in a prestressed state in which the C-clamp continues to exert a force drawing lip  6  and adapter  12  towards each other and continues to firmly engage the adapter as described above. 
     To loosen the connection, the hydraulic actuator is reenergized sufficiently to widen the wedge-shaped space between the C-clamp and the actuator so that wedge  100  can be manually withdrawn. Thereafter, upon the depressurization of the hydraulic actuator, the C-clamp returns to its relaxed, stress-free position, enabling a withdrawal of the C-clamp and the hydraulic actuator for replacing the adapter with a fresh one, as was described in more detail above. 
     The constructional details of the internal components of the hydraulic actuator  52  shown in  FIG. 7  were described earlier and are not here repeated again. It is sufficient to state that internally the hydraulic actuator has preferably two spaced-apart pistons  76  which are drawn into a refracted position by tension springs (not shown in  FIG. 7 ). Upon introducing pressurized fluid into the hydraulic actuator, pistons  76  are forced in an aft direction into engagement with front surface  54  of C-clamp  38  to prestress the C-clamp and engage the adapter with arms  42  of the C-clamp. 
     An important feature of the present invention is the ease with which the connection can be applied and released without damaging parts not subject to wear and tear during ordinary use of the excavating equipment. For each application or release of the connection, it is necessary to pressurize and depressurize the interior of the hydraulic actuator. Pressurized fluid is supplied via a suitable conduit and nipple  92  into the interior of the actuator. 
     To facilitate the placement and withdrawal of the hydraulic actuator, and to enable replacement of parts that may become damaged during ordinary use of the excavating equipment, preferably the upper end of the actuator is partially formed by a top plate  120  which has a pair of spaced-apart, horizontal web sections  122 . The top plate defines the uppermost end of the main body of the actuator. Pressure fitting  92  includes an elongated, enlarged diameter threaded tubular extension  124  which extends through an open hole in the upper horizontal web  122  of top plate  120  and threadably engages a threaded hole in main hydraulic actuator body portion  126 . The pressure fitting includes a convenient hexagonal head which can be used to torque the threaded end of the fitting into the threaded hole in the main body portion to thereby simultaneously secure top plate  120  in place and mount pressure fitting  92  on main actuator body portion  126 . 
     The portion of pressure fitting  92  extending into open end  112  (shown in  FIG. 2  only) of the hydraulic actuator is protected against contamination and damage by a strong, preferably a generally solid, rectangularly shaped metal, e.g. steel, cap  128  which is essentially a solid block of steel that has a center bore  130  which is configured to fully accommodate therein the nipple end of the pressure fitting through which pressurized fluid is supplied to the interior cavities of the hydraulic actuator, as is generally illustrated in  FIG. 7 . Preferably, the space between the pressure fitting and the surrounding walls of center bore  130  receives an elastomeric sleeve (not shown in the drawings) that snugly but removably slips over the nipple of the pressure fitting and otherwise fills up the annular space surrounding the nipple, as can be seen in  FIG. 8 , to keep contaminants out. 
     To manually removably secure cap  128  to the hydraulic actuator  52 , a spring-biased detent ball  132  is suitably mounted in cap  120  so that the ball slightly protrudes past a side of the cap facing an upstanding wall  134  of actuator top plate  120 . Wall  134  has correspondingly spaced-apart depressions  136  for receiving the spring-biased balls  132 . 
     Cap  128  and the matching surfaces of hydraulic actuator  52 , and in particular the matching surfaces formed by actuator top plate  120 , are dimensioned so that the cap fits snugly but readily movable into open end  112  (shown in  FIG. 2 ). The spring-loaded detent balls  132 , however, retain the cap in place during normal use of the excavating equipment. Nevertheless, the cap can be manually removed by pulling it upwardly relative to the hydraulic actuator, which disengages the detent balls from the depressions  136  in the actuator so that the cap can be removed, thereby providing access to the nipple of the pressure fitting  92 . 
     To facilitate the removal of the cap, and in particular to permit ready removal of the cap even if it and/or its surfaces that mate with the remainder of the actuator are heavily contaminated and/or damaged, for example from having suffered heavy blows or impacts against it, upstanding wall  134  of top plate  120  includes a cut-out  138  which defines at a level below the uppermost surface of cap  128  a flat, generally horizontal support surface  138 . A recess  142  is formed in the side of cap  128  facing the upstanding wall  134  and straddles support surface  138  so that at least a portion of the recess is located above the support surface when cap  128  is positioned in place. This provides access to the recess from the exterior of connection  24 . The cap can be forcibly removed by supporting a suitable prying tool, which can be a heavy-duty flat screwdriver, an L-shaped metal bar with a long grab bar and a short prying end capable of engaging recess  142  in the cap when the bend of the L-shaped member is supported on the horizontal support surface  138 , or a similar tool with which the cap can be forced upwardly relative to upstanding actuator wall  134  to pry the cap loose from the actuator and remove it. 
       FIG. 9  shows another embodiment of the present invention which is particularly suitable for use in connection with dragline buckets, and in particular for replacing worn adapters of such buckets. 
     As is true for the previously described embodiments of the invention, a dragline adapter  144  is positioned over a bucket  2  having a lip  6  that ends in a lip end  8 . A forward end of adapter  144  suitably mounts a tooth  10  as seen in  FIG. 9 . 
     Adapter  124  has a nose portion  146  that receives the tooth and which has an interior cut-out  148  that snugly engages bucket lip  6  so that lip end  8  is spaced some distance, typically between about ⅛″ to ⅜″, from a bottom end  150  of the cut-out. If desired, the lip end  8  can also be allowed to extend all the way to the end  150  of the cut-out. 
     Lip  6  of bucket  2  and upper and lower legs  152 ,  154  of adapter  144  define an opening  26  in the lip and openings  28  in the adapter which are non-contiguous and generally vertically aligned but horizontally offset so that the forward and aft ends  32 ,  30  of the openings in the adapter legs are positioned forward of the corresponding forward and aft surfaces  36 ,  34  of opening  26  in the lip. 
     A hydraulic actuator  52  constructed as above described and a cooperating wedge  100  are disposed in the generally vertically aligned but horizontally slightly offset openings  26 ,  28  in the lip and the adapter legs, as is shown in  FIG. 9 . 
     When it is desired to secure the adapter to the bucket lip  6 , and following the insertion of a hydraulic actuator  52  and a cooperating wedge  104  in the generally aligned openings  26 ,  28  in the lip and the adapter legs, the hydraulic pistons  76  (only schematically shown in  FIG. 9 ) are energized as above described. Upon energization, the pistons push in a forward direction towards front wall  36  of opening  26  in the lip, while an aft side  156  of the actuator pushes in an aft direction against aft walls  30  of openings  28  in the adapter legs. The resulting force urges the lip and the adapter towards each other. The engagement of the bucket lip  6  by interior adapter cut-out  148  and/or the bottoming out of lip end  8  in the adapter cut-out  148  causes an elastic elongation of the adapter legs under the force exerted by pistons  76 . This elongation will typically be most pronounced in those portions of the adapter legs adjacent each side of the openings  28  in the adapter legs, although other portions of the adapter leg will typically be slightly elongated as well. Once the desired elongation has been reached, wedge  100  is manually pushed down until the cooperating undulations  64  on the hydraulic actuator and the wedge prevent further downward movement. Thereafter, the pressure in the hydraulic actuator is reduced or eliminated, which permits the previously elastically elongated portions of the adapter legs to contract until wedge  100  prevents further contracting movements. The engagement of the hydraulic actuator by the edge will maintain the adapter legs in their slightly reduced prestressed state and will prevent the adapter legs from returning to their relaxed state, thereby maintaining the horizontal force which tightens the adapter on the bucket lip, as described in greater detail above. 
     Pursuant to a further development of the present invention, a digging tooth  157  is replaceably and immovably secured to a front portion  160  of an adapter  10  as illustrated in  FIGS. 10-12 . The front portion defines upper and lower, forwardly converging engagement surfaces  158 ,  159 . The front portion ends in a nose of a reduced height and defines a forwardly facing stop ledge  162 . A hole  164  extends vertically through the engagement surfaces at a point aft of the stop ledge. 
     Tooth  157  has a body  166  that terminates in a tip  167 . Rearwardly extending and diverging upper and lower legs  168 ,  170  extend from the body along the corresponding upper and lower engagement surfaces of the adapter. A hole  174  extends through each leg of the tooth. To limit relative movement of the tooth in the aft direction the tooth and the adapter are configured so that the adapter abuts (not shown in  FIG. 10 ) against tooth body  166 . Alternatively, the respective corresponding engagement surfaces of the tooth and the adapter can be provided with cooperating stop ledges and grooves  162  to limit aft relative movements of the tooth. Additionally, to limit or prevent friction forces between the opposing engagement surfaces of the tooth and the adapter the respective surfaces can be made non-contiguous, e.g. by forming a slight gap  172  between them as seen in  FIG. 10 . Alternatively, the engagement surfaces of the front end of the adapter and the legs of the tooth can be configured so that they abut when the tooth is pulled over the adapter and the tooth engages stop ledge  162  on the adapter, thereby eliminating the gap  172  shown in  FIG. 10 . 
     Holes  174  are substantially aligned with hole  164  in the adapter. The portion of each tooth leg aft of the respective holes  174  forms an engagement section  175  for a power supply unit  176 , preferably a hydraulic actuator, as further described below. The aft and front ends of hole  164  in the adapter are located rearward of the aft and front ends of the respective holes in tooth legs  168 ,  170 . 
     Hydraulic actuator  176  is primarily located within vertical adapter hole  14 . Its housing  178  extends partially into holes  174  in the legs of the tooth. An aft side  180  of the housing includes upper and lower, rearwardly facing force transmitting ledges  182  which abut vertically oriented walls of the engagement sections of the tooth. Ledges  182  are preferably also employed as positioning edges that engage corners  184  in the engagement sections of the tooth to facilitate the proper positioning of the actuator in the holes during the assembly of the connection. 
     The forwardly facing side of housing  178  is angularly inclined relative to the vertically oriented front surface  165  of adapter hole  164  and forms a wedge-shaped space  186  between them as shown in  FIG. 10 . A wedge  187 , constructed and operating as is further described below, is inserted into the wedge-shaped space. 
     Actuator housing  178  includes a forwardly open bore in which a piston  188  reciprocates. The open end of the bore is formed by a cover plate  191  which is secured to the housing with bolts  193 . The piston is driven forwardly by applying a high pressure fluid, such as oil or grease, for example, to the aft side of the piston via a pressure fitting  194  and a pressure fluid conduit  194 . A compression spring  198  between cover plate  191  and the forward facing side of piston  188  retracts the piston into the bore when no hydraulic pressure is applied via fitting  192  to the other side of the piston. A removable protective cap  196 , preferably made of a resilient material such as rubber or certain plastics, is pressed and frictionally retained inside an appropriately, preferably upwardly oriented opening formed in actuator housing  178  as seen in  FIG. 2 . This positioning of the cap in the hole shields the cap and the pressure fitting against dirt, abrasives and the like that might enter the adapter hole through its upwardly open end. 
     To install a fresh tooth  157  on adapter  12 , the tooth is initially slipped over engagement surfaces  158 ,  159  of the adapter to substantially align the holes  174  in the tooth legs with hole  164  in the adapter. Hydraulic actuator  176  is inserted into the aligned holes and pushed rearwardly to operatively align the force transmitting ledges  182  of the adapter with corners  184  of the tooth. This maintains the housing properly positioned inside the hole and prevents it from moving vertically inside the hole while the tooth is being mounted on the adapter. 
     Hydraulic pressure is next applied to the piston via pressure fitting  192  which forces piston rod  190  in a forward direction against the forward surface  165  of hole  164  in the adapter. The aft surface  180  of the housing is forced rearwardly relative to the engagement sections  175  of the tooth legs which stresses and thereby elongates the tooth legs. This correspondingly increases the horizontal width of wedge-shaped space  186 . 
     A wedge  187 , with a width is slightly less than that of the widened wedge-shaped space, but wider than the width of the wedge-shaped space when the piston is deenergized is then dropped into the wedge-shaped space. Wedge  187 , like wedge  100  shown in  FIG. 2 , is fork-shaped and has two downwardly extending legs  202  which are spaced apart to allow passage of piston rod  190  into engagement with front vertical wall  165  of adapter hole  164 . 
     When the actuator is deenergized the legs  168 ,  170  of the tooth remain in their stressed condition because wedge  187 , together with actuator housing  178  prevent the tooth legs from returning to their relaxed, unstressed state. The opposing surfaces of wedge  187  and cover plate  191  have undulations  200  which interlock to prevent relative vertical movements between them when the hydraulic actuator is deenergized. 
     The horizontally acting force applied to the stressed tooth is selected so that the tooth remains immovably secured to the front portion of the adapter following the deenergization of the actuator by appropriately dimensioning the tooth and its legs so that a residual horizontal force generated by the tooth is sufficient to maintain the immovable connection of the tooth until the actuator is again activated. 
     It is anticipated that the teeth will mostly be mounted on adapters which are interposed between the container front end, e.g. its front lip, and the tooth as described above. However, if preferred, the teeth can be immovably secured directly to configured container lips which, for simplification and as is seen in  FIG. 10 , are identified by reference “ 12 A”.