Tool Coupler

The present invention is generally directed to coupling apparatus for releasably securing a tractor linkage to a tool such as: bucket, blade, ripper, auger, etc.

The task of connecting and disconnecting a tool on the linkage of a tractor such as a backhoe, excavator, loader, etc. has been simplified a great deal by the development of releasable quick change connectors. The connector includes a second coupling element on the tractor linkage and a first coupling element which is complementary with the second coupling element on each tool which is to be connected to the tractor linkage. A typical connecting system includes a cylindrical cross member at the front end of the tool and a pair of spaced hooks at the front end of the tractor linkage for engaging the cross member. When the tractor linkage is positioned in a coupling mode on the tool, the tool is secured to the tractor linkage by means of complementary locking means at the rear end of the tractor linkage and the tool. This type of coupler system permits a wide range of tools to be connected to any type of tractor or equivalent machine. The coupler system permits a single operator to change tools, in some cases, without leaving the operator's compartment.

One of the problems with the prior art tool coupling devices is that the interengaging elements of the tractor linkage and the tool wear, due to the high operating forces and extensive use of the equipment. As these interengaging parts begin to wear, the connections between the tractor linkage and the tool become loose. This adversely affects the operation of the tractor and, eventually, leads to downtime for the tractor and tools in order to repair or replace worn parts. These and other difficulties experienced with the prior art devices have been obviated by the present invention.

It is, therefore, a principal object of the present invention to provide a coupling apparatus for a tractor linkage which enables the tractor linkage to be coupled to a tool, easily and accurately.

Another object of the invention is the provision of a coupling apparatus for a tractor linkage which enables the tractor linkage to be coupled to a tool with a precise snug fit and to maintain the snug fit throughout the operation of the tool.

A further object of the present invention is the provision of a coupling apparatus for a tractor linkage which minimizes wear of the engaging portions of the coupling. It is another object of the present invention to provide a coupling apparatus for a tractor linkage which includes adjusting means for compensating for wear of the surfaces of the tractor linkage which engage complementary surfaces of the tool to avoid replacement of worn components and down time of tractor linkage and tool.

A still further object of the invention is the provision of a coupling apparatus for a tractor linkage which provides the superior coupling characteristics recited above for a tractor linkage which also includes a swinging capability. With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

In general the invention consists of a coupling apparatus for releasably securing a tool to the linkage of a tractor such as a backhoe, excavator, loader, etc. The coupling apparatus includes a second coupling element which is fixed to the lower end of the dipper stick of a tractor linkage and a first coupling element which is fixed to the upper end of the tool. One of the coupling elements has a generally upwardly facing third engaging surface for engaging a downwardly facing first engaging surface of the other coupling element. This provides the main coupling connection between the first and second coupling elements. One of the coupling elements has a second engaging surface which is spaced from the first engaging surface. The other coupling element has a fourth engaging surface. When the tractor linkage is coupled to the tool, a primary downward preloading force is imparted to the rear end of the tractor linkage relative to the tool along a primary line of action which is at a right angle to the generally horizontal top end of the tool. When the first and second coupling elements are brought together in a coupling mode, the second and fourth engaging surfaces engage and form a fulcrum between the tool and the tractor linkage. The primary downward preloading force creates a moment about the fulcrum which is formed by the second and fourth engaging surfaces for forcing the third engaging surface against the first engaging surface with a resultant upward acting force along a resultant line of action which is at an acute angle to the primary line of action to provide stability to the coupling apparatus during normal operation of the tool and to maintain the first engaging surface in contact with the third engaging surface. The first coupling element has a first locking element at the rear end of the first coupling element for engaging a complementary second locking element at the rear end of the second coupling element and for receiving a connector to lock the first and second locking elements together when the coupling apparatus is in the coupling mode. An upward reactive force is formed at the fulcrum in response to the primary downward preloading force along a resultant line of action which is at an acute angle to the primary line of action. The connector effective for transmitting a downward or upward working force from the tractor linkage to the rear end of the tube.

The character of the invention, however, may be best understood by reference to one of its structural forms, as illustrated by the accompanying drawings, in which:

FIG. 1 is a top plan view of a coupling apparatus embodying the principals of the present invention;

FIG. 2 is a side elevational view of the coupling apparatus, looking in the direction of arrow II of FIG. 1;

FIG. 3 is a top plan view of a portion of a coupling apparatus which is fixed to a materials handling tool;

FIG. 4 is a side elevational view of a coupling apparatus with the coupling elements separated in a non-coupling mode and, with portions in section;

FIG. 5 is a fragmentary view of one of the coupling elements, looking in the direction of arrow V of FIG. 4;

FIG. 6 is a fragmentary view of the other of the coupling elements, looking in the direction of arrow VI of FIG. 4;

FIG. 7 is a view similar to FIG. 4, showing the coupling elements in transition between the uncoupling mode and the coupling mode;

FIG. 8 is a view similar to FIGS. 4 and 7, showing the coupling elements in the coupling mode;

FIG. 9 is a fragmentary view of the coupling elements, looking in the direction of arrow IX of FIG. 8;

FIG. 10 is a fragmentary side elevational view of the coupling apparatus of the present invention which is similar to FIG. 8 and shows a modified tractor linkage which is provided with a swinging mechanism;

FIG. 11 is a fragmentary side elevational view of a first modified coupling which includes tensioning and wear compensating means; and

FIG. 12 is a fragmentary side elevational view of a second modified coupling which includes tensioning and wear compensating means.

Referring first to FIGS. 1-4, the coupling apparatus of the present invention is generally indicated by the reference numeral 16 for coupling a tractor linkage which is generally indicated by the reference numeral 18 to a tool which, by way of example, is a bucket, generally indicated by the reference numeral 20.

Referring particularly to FIGS. 1-8, the tractor linkage 18 includes dipper stick or arm 22 which is pivotally connected to a main body, generally indicated by the reference numeral 34, by a hinge pin 42. A bucket link 24 is also connected to the main body 34 by a hinge pin 40. A guide link 26 is connected to the dipper stick 22 at one end by a hinge pin 32 and at its other end to the upper end of the guide link 24 by a hinge pin 28 which is also connected to a piston 30. The tractor linkage 18 is described in U.S. Pat. No. 3,934,738 which is incorporated herein by reference. Further details of the connection and the operation of the tractor linkage can be found in this patent. The main body 34 includes a pair of spaced vertical plates 36 which are connected, in part, by a cross plate 38. The tractor linkage 18 is adapted to exert a downward working force on the upper rearward portion of the bucket 20 for actuating the bucket 20 when the tractor linkage is in a coupling mode relative to the bucket 20.

The bucket 20 has a pair of vertical side walls 44, a back wall 46, a bottom wall 48 and a front opening 50. The bucket 20 has top horizontal plate 52 which has a top opening 54. A cross tube 56 extends between the side plates 44 and has an outer cylindrical first engaging surface 57. A horizontal bar 58 is fixed to a pair of spaced vertical brackets 64 which are, in turn, fixed to the rear end of the cross tube 56. A shim plate 60 is removably connected to the bar 58 by a pair of fasteners 62. The bar 58 has end surfaces 59. The shim plate 60 has an upwardly facing second engaging surface 61 which is spaced from the first engaging surface and is at an acute angle to the primary line of action 19 of the tractor linkage 18 when the tractor linkage is in its coupling mode with the tool 20. The bucket 20 is shown in FIGS. 4, 7 and 8 in its normal resting position on the ground prior to being coupled with the tractor linkage 18, wherein the generally horizontal upper periphery of the bucket is at an angle to the horizontal. However, during operation of the tractor, the upper end of the bucket is generally horizontal.

The bucket 20 has a cylindrical bearing 66 which extends upwardly from the rear end of the bucket. The bearing 66 has a horizontal cylindrical bore 67. The main body 34 has a cylindrical bearing 68 at its rear end. The bearing 68 has a horizontal cylindrical bore 70 and a semi-circular projection or crescent 72 at the rearward end of the bearing 68. When the coupling apparatus of the present invention is moved from its uncoupling mode as shown in FIG. 4 to its coupling mode as shown in FIG. 8 the rearward end of the cylindrical beating 68 and 66 abut so that the horizontal bores 67 and 70 are aligned and the crescent 72 engages the upper cylindrical surface of the bearing 66 at the forward end of the bearing 66. This helps to position correctly the beating 68 relative to the bearing 66. The cylindrical bearings 66 and 68 constitute complementary first and second locking elements 63 and 65, respectively, which are locked together by a connector pin 73 the connector pin 73 is inserted into the bores 67 and 70 so that the forward end of the pin extends forwardly of the bearing 68 as shown in FIG. 8. The forward end of the pin 73 has a transverse bore 74 for receiving a latch pin 76 to secure the connector pin 73 in its locking position. The central longitudinal axis of the bore 70 is slightly higher than the central longitudinal axis of the bore 67. When the pin 73 is inserted into the bores 70 and 67, the rear end of the tractor linkage is forced downwardly relative to the tool 20 with a primary downward preloading force along a primary line of action 19 through the pin 73. The forward end of the pin 67 is beveled to enable the pin to be inserted into the misaligned bores 67 and 70. The preloading force is substantially less than the working force for operating the tool or bucket 20

The main body 34 has a pair of downwardly extending spaced vertical hooks 78. Each hook 78 has an upwardly and forwardly facing surface 79. Each surface 79 is concave and has a radius of curvative which is substantially equal to the radius of the cylindrical surface 57. Surfaces 79 collectively form a third engaging surface. A cross bar 80 extends horizontally between the hooks 78 and is fixed to the cross plate 38. Each hook 78 has an inwardly facing surface 77 and a downwardly and inwardly facing surface 82 and is shown most clearly in FIGS. 4 and 5. The bar 80 has a downwardly facing fourth engaging surface 86 which is at an angle to the primary line of action 19 of the tractor linkage when the main body 34 is coupled to the bucket 20, as shown in FIG. 8. When the coupling apparatus 16 of the present invention is in its coupling mode, as shown in FIG. 8, the fourth engaging surface 86 of the bar 80 engages the second engaging surface 61 of the shim plate 60.

When the tractor linkage 18 is moved from its uncoupled position relative to the bucket 20, as shown in FIG. 4, to its coupled position, as shown in FIG. 8, the hooks 78 are inserted through the opening 54 so that the hooks pass rearwardly of the bar 58 and are positioned below the tube 56, as shown in FIG. 7. Also, in this position, the downwardly facing fourth engaging surface 86 of the bar 80 is located above the upwardly facing second engaging surface 61 of the shim plate 60. As the main body 36 continues to move towards the coupling position as shown in FIG. 8, the fourth engaging surface 86 engages the second engaging surface 61. The engagement of the second and fourth engaging surfaces 61 and 86, respectively, forms a fulcrum between the tool 20 and the tractor linkage 18. There is sufficient elasticity in the coupling apparatus so that when the pin 73 is forced into the misaligned bores 67 and 70, the bores 67 and 70 become aligned. The primary downward preloading force along the primary line of action 19 produces a moment about the fulcrum which is formed by the engaging surfaces 86 and 61. This causes the third engaging surface 79 of the hooks 78 to be forced against the first engaging surface 57 of the tube 56 with a resultant upward acting force along a resultant line of action 89. This insures that the surfaces 57 and 29 remain in tight engagement throughout the operation of the tool. The resultant line of action 89 is at an acute angle to the primary line of action 19. The preferred angle of the resultant line of action relative to the primary line of action 19 is from 15.degree. to 75.degree.. The primary downward preloading force and the resultant upward acting force are opposed by an upward reactive force at the fulcrum along a reactive line of action, indicated by arrow 90 in FIG. 8. The reactive line of action 90 is parallel to the resultant line of action 89 and transverse to the surfaces 61 and 82. This maintains the surface 79 in tight engagement with the surface 57 during operation of the tractor in all of its phases of operation. This close engagement between the surfaces 57 and 79 prevents foreign material such as dirt from entering between the engaging portions of the surfaces 57 and 79 and significantly reduces the amount of wear on these engaging portions.

As the hooks 78 are moved toward their final position, as shown in FIG. 8, the end surfaces 59 of the bar 58 engage the inwardly facing surfaces 77 of the hooks 78 to provide lateral stability to the coupling of the tractor 18 and the tool 20 when the coupling apparatus 16 is in its final coupling position as shown in FIGS. 8 and 9. The end surfaces 59 are guided into engagement with the surfaces 77 by the cam surfaces 82. The surface 79 of each hook 78 is concave and has the same radius as the surface 57 of the cross tube 56 for snugly engaging the rear half of the cross tube 56 when the coupling apparatus 16 of the present invention is in the coupling position as shown in FIG. 8. The forward end of each hook 78 has a flat upwardly facing edge surface 81 for engaging the corresponding flat upwardly facing surface which is found on many tools which are still in existence. This enables the tractor linkage 18 which is provided with the coupling apparatus of the present invention to be used with tools 20 which are provided with the coupling apparatus of the present invention as well as with certain prior art tools which are still in existence. In the example shown in the drawings, the surfaces 79 of the hooks 78 and the surface 86 of the cross bar 80 constitute a second coupling element. The outer cylindrical surface 57 of the cross tube 56 and the surface 61 of the shim plate 60 and the first locking element 65 constitute a first coupling element, the apparatus which is shown and described constitutes a preferred embodiment of the invention. However, other variations of the first and second coupling elements are possible. For example, the hooks 78 and bar 80 can be part of the bucket 20 and the tube 56 along with the bar 58 and the shim plate 60 can be part of the main body 34.

During operation of a tractor which is provided with the coupling apparatus of the present invention, the lifting force between the main body 34 and the bucket 20 is transmitted to the upwardly facing portions of the hooks 78 and the downwardly facing portions of the cross tube 56. The pushing force is transmitted to the forwardly facing portions of the hooks 78 and the rearwardly facing portion of the cross tube 56. The downward working force from the tractor linkage 18 is transmitted to the tool 20 through the pin 73.

Wear between the engaging surface portions of the tractor coupling and the bucket is greatly reduced by the coupling of the present invention. However, over a period of time, wear does occur to one or more of the engaging surfaces. Eventually the initial "preloading" of the coupling is lost and the coupling becomes loose at the points of engagement between the tractor linkage and the bucket. This enables foreign material to enter between the surfaces 57 and 79 and between the surfaces 60 and 86, which causes additional wear to occur at the engaging surfaces. When the coupling apparatus 16 loosens because of wear, the shim plate is removed from the bar 58 by removing the fasteners 62. One or more of the shims are applied to the horizontal bar 58 and the shim plate 60 is reapplied to the bar 58. This raises the surface 60 so that when the tractor linkage 18 is applied to the bucket 20, the coupling 16 is returned to its "preloaded" state. If desired, the shim plate 60 can also be replaced by a thicker shim plate to achieve the same results.

In the preferred embodiment of the present invention, the bar 80 is substantially harder than the shim plate 60 so that any wear which results from the engagement of the surfaces 86 and 61 is more likely to be to the shim plate 60.

Referring to FIG. 10, there is shown a modified coupling apparatus, generally indicated by the reference numeral 98, which is applied to the bucket 20 and a modified tractor linkage which is generally indicated by the reference numeral 100. The tractor linkage 100 is identical to the tractor linkage 18 and has a main body portion which is generally indicated by the reference numeral 34'. The main body portion 34' is similar to the main body portion 34 except that it includes a tool tilting apparatus which is generally indicated by the reference numeral 102. The swinger apparatus 102 is a standard apparatus which enables the materials handling tool and a coupling apparatus 98 to swing relative to the vertical plates 36' of the main body 34' about a front to back horizontal axis 104. The hooks 78' of the hitch 100 are fixed to a swinger housing 105 which is pivotally mounted in forward and rearward bearings 106 and 68', respectively, for swinging about the horizontal axis 104. The swinging motion is controlled by a hydraulic actuator which is generally indicated by the reference numeral 108 which is operatively connected to the hydraulics of the tractor. The rearward portion of the bearing 68' is similar to the bearing 68 and cooperates with the bearing 66 of the bucket 20 in the same manner as the bearings 68. The bearing 68' has a horizontal cylindrical bore 109 which is horizontally aligned with the bore 67 of the bearing 66 for receiving a first cylindrical portion 110 of a connector pin 73'. The bearing 68' has an upwardly extending flange 111 which has an aperture 112 for receiving a second cylindrical projection 113 of the connecting pins 73'. The projection 113 has a transverse bore 114 for receiving a latch pin 76' after the projection has been inserted through the aperture 112.

Referring to FIG. 11, there is shown a first modified coupling apparatus which is generally indicated by the reference numeral 119 and which forms part of a first modified tractor linkage 18' and a first modified tool or bucket 20'. The first modified coupling apparatus 119 is identical to the coupling apparatus 16 with respect to the locking elements, the hooks 78, and the tube 56. The first modified coupling apparatus 119 differs from the coupling apparatus 16 in the area where a fulcrum is formed between the tractor linkage 18 and the bucket 20. The first modified coupling apparatus 119 includes at the fulcrum adjusting means, generally indicated by the reference numeral 120. The adjusting means 120 includes the cross bar 80 which is fixed to the cross plate 38, an L-shaped bar, generally indicated by the reference numeral 122, and a tapered wedge block 128. The L-shaped bar 122 includes a forward leg portion 124 which is fixed to the top edges of the brackets 64 and a rear upwardly extending leg portion 126. A screw 132 extends freely through the leg portion 126 and is threaded into a bore 130 in the wedge block 128. A spring washer 134 is located on the rear side of the leg portion 126 and the head of the screw 132. A lock nut 136 is threaded onto the screw 132 at the forward side of the leg portion 126. The wedge block 128 has an upper surface 129 which bears against the lower surface 86 of the cross bar 80. The wedge block 128 is moved forwardly and rearwardly relative to the L-shaped bar 122 by turning the screw 132. The rearward and forward movement of the wedge block 128 causes the surface 129 to move rearwardly and forwardly from the lower surface 86 of the cross bar 80 when the tractor linkage 18' is in its coupling mode relative to the tool 20', as shown in FIG. 11. When the first modified coupling apparatus 119 is initially installed, the wedge block 128 is positioned so that when the tractor linkage 18' is in the coupling mode relative to the tool 20' the surface 129 of the wedge block bears against the lower surface 86 of the cross bar 80 with sufficient pressure to create a "preloading" condition which forces the third engaging surface 79 of the hooks 78 against the surface 57 of the tube 56. In the event of wear to any of the engaging surfaces, the wedge block 128 is adjusted forwardly. This is accomplished by loosening the lock nut 136 and turning the screw 132. As the screw 132 is backed out of the aperture 130, wedge block 128 is adjusted forwardly. The forward advance of the wedge block 128 causes the surface 129 to move toward the lower surface 86 and return the coupling apparatus 119 to its original "preloading" condition.

Referring to FIG. 12, there is shown a second modified coupling apparatus, generally indicated by the reference numeral 139 and which forms part of a second modified tractor linkage 18" and a second modified tool or bucket 20". The second modified coupling apparatus 139 is identical to the coupling apparatus 16 except for the locking means at the rear end of the tool 20" and tractor linkage 18" The locking means for the second modified coupling apparatus 139 includes tensioning and wear compensating means which is generally indicated by the reference numeral 140.

The tensioning and wear compensating means 140 comprises a first protrusion 142 which is fixed to the rear end of the tractor linkage 18" and a second protrusion 144 which is fixed to the rear portion of the tool 20". The second protrusion 144 has a cylindrical bore 154 which extends along a horizontal axis 147. The axis 147 is transverse to the primary line of action 19. The first protrusion 142 has a bore 143 which is at an acute angle to the axis 147 when the tractor linkage 18" is in the coupling mode with the tool or bucket 20" as shown in FIG. 12. The lower end of the bore 143 has an upwardly facing surface 146 which is at an acute angle to the axis 147. A cam block 149 is slidably mounted within in the bore 143 and has the shape of a parallelogram in cross section as shown in FIG. 12. The cross-sectional shape of the cam block 149 matches the cross-sectional shape of the bore 143. The cam block 149 has a downwardly facing surface 145 which engages the upwardly facing surface 146 of the first protrusion 142. The cam block 149 has a central horizontal bore which is co-axial with the axis 147 and which is axially aligned with the bore 154 when the tractor linkage 18" is in coupling engagement with the tool 20". A cylindrical connector pin 155 is slidably mounted within the bore 153 along the horizontal axis 147. The forward end of the pin 155 is slidably mounted within the cylindrical bore 161 of a housing 160 which is fixed to the upper end of the tractor linkage 18". A spring 162 is located within the bore 161 for biasing the pin 155 rearwardly toward the bore 154. A collar 148 is fixed to the pin 155 for engaging block 149 when the tractor linkage 18" is in the coupling mode with the tool 20" and the pin 155 is in the lock position as shown in FIG. 12. A retracting pin 150 is fixed to the pin 155. The upper end of the retracting pin 150 has a finger knob 151 which enables an operator to retract the pin 155 from its locked position against the bias of the spring 162 to an unlocked position wherein the rearward end of the pin 155 is clear of the bore 154.

When the tractor linkage 18" is brought into coupling engagement with the tool 20", the pin 155 is maintained in its unlocked or retracted position and then released so that the pin 155 slides freely through the bore 153 and into the bore 154. The collar 148 engages the cam block 149 and urges the block 149 rearwardly under the bias of the spring 162. This causes the downwardly facing surface 145 of the block 149 to forcefully engage the upwardly facing surface 146 of the first protrusion 142. Since the surfaces 145 and 146 are at an acute angle relative to the horizontal axis 147, the rearward movement of the surface 145 along the surface 146 causes the first protrusion 142 to move downwardly relative to the second protrusion 144. This creates a primary downward preloading force which causes the tractor linkage 18" to pivot about the fulcrum which is formed between the bar 80 and the shim plate 60 and causes the forwarding facing surfaces 79 of the hooks 78 (first engaging surface) to bear tightly against the rearwardly facing portions of the surface 57 of the cylindrical cross tube 56. This is equivalent to the "preloading" condition which was described in connection with the coupling apparatus 16 which is shown in FIGS. 1-9. The tensioning and wear compensating means 140 maintains the "preloading" condition after the first, second, third, and fourth engaging surfaces sustain wear during subsequent use of the tractor linkage 18" and the tool 20". As wear occurs in any of these engaging surfaces, the cam block 149 is moved rearwardly in an additional amount by the bias of the spring 162. This rearward movement of the block 149 causes the tractor linkage 18" to move downwardly relative to the tool or bucket 20" to compensate for wear and to maintain the "preloading" condition. The downward working force from the tractor linkage 18" is transmitted to the tool 20" through the pin 55.

Clearly, minor changes may be made in the form and construction of the invention without departing from the material spirit thereof. It is not, however, desired to confine the invention to the exact form herein shown and described, but it is desired to include all such as properly come within the scope claimed.