A coupler for a wheel loader

Abstract

A coupler for a wheel loader is used for coupling an attachment ( 102 ) to a lifting arm of the wheel loader. A bracket ( 100 ) is installed between the lifting arm and the attachment ( 102 ). The bracket's back face is pivotally connected to a lifting arm and the bracket's front face is detachably connected to the attachment ( 102 ). The attachment ( 102 ) has a pair of protrusions ( 104 a, 104 b ) rearwardly extending from the lower back of the attachment ( 102 ) and have locking holes pierced through their width. The bracket has a pair of receiving slots ( 108 a, 108 b ) formed at the lower front of the bracket and engaged with the protrusions( 104 a, 104 b ). The coupler has a shaft ( 202 ), and a pair of locking pins ( 204 a, 204 b ) combined with the shaft by threads ( 216 a, 216 b ). The threads ( 216 a, 216 b ) formed at one end of the shaft ( 202 ) are right handed and the threads ( 216 a, 216 b ) formed at the other end of the shaft ( 202 ) are left handed. When users turn the shaft ( 202 ) in one direction,the locking pins ( 204 a, 204 b ) are extended and engaged with the locking holes (a coupling position). When users turn the shaft in the other direction,the locking pins are shortened and released from the locking holes (a release position).

1 . A coupler for detachably connecting an attachment to the free end of a lifting arm on a wheel loader, comprising:
 a bracket with a back face pivotally connected to said lifting arm and a front face detachably connected with said attachment;   a first and a second protrusions rearwardly extending from the lower back of said attachment and laterally spaced apart from each other, said first protrusion having a first locking hole pierced through its width and said second protrusion having a second locking hole pierced through its width;   a first and a second receiving slots formed at the lower front of said bracket and engaged with said first protrusion and said second protrusion, respectively;   a shaft which has threads formed at both ends and installed at the lower part of said bracket, wherein the threads formed at the one end of said shaft are right handed and the threads formed at the other end of said shaft are left handed;   a first locking pin which has threads corresponding to the threads formed at the one end of said shaft;   a second locking pin which has threads corresponding to the threads formed at the other end of said shaft;   a first holder fixed to said bracket and supporting said first locking pin so as to prevent said first locking pin from being rotated when said shaft is driven to rotate, thereby enabling a rectilinear movement of said first locking pin and disabling a rotational movement of said first locking pin;   a second holder fixed to said bracket and supporting said second locking pin so as to prevent said second locking pin from being rotated when said shaft is driven to rotate, thereby enabling a rectilinear movement of said second locking pin and disabling a rotational movement of said second locking pin; and   wherein said coupler has a coupling position of the attachment in which said locking pins are extended and engaged with said locking holes of said protrusions as said shaft rotates in one direction, and a release position of the attachment in which said locking pins are shortened and released from said locking holes of said protrusions as said shaft rotates in the other direction.   
     
     
         2 . The coupler of  claim 1 , wherein:
 said first locking pin is longitudinally divided into a cylindrically cross-sectioned outer part and a non-cylindrically cross-sectioned inner part, said outer part being subject to be engaged with said first locking hole;   said second locking pin is longitudinally divided into a cylindrically cross-sectioned outer part and a non-cylindrically cross-sectioned inner part, said outer part being subject to be engaged with said second locking hole;   said first holder has a contacting surface corresponding to the non-cylindrical contour of said inner part of said first locking pin; and   said second holder has a contacting surface corresponding to the non-cylindrical contour of said inner part of said second locking pin.   
     
     
         3 . The coupler of  claim 2 , wherein:
 the cross-section of said inner part of said first locking pin is partially flattened cylindrical shape; and   the cross-section of said inner part of said second locking pin is partially flattened cylindrical shape.   
     
     
         4 . The coupler of  claim 2 , wherein:
 the cross-section of said inner part of said first locking pin is polygonal shape; and   the cross-section of said inner part of said second locking pin is polygonal shape.   
     
     
         5 . The coupler of  claim 2 , wherein:
 the longitudinal length of said inner part of said first locking pin is longer than or at least equal to the rectilinear moving stroke of said first locking pin along said shaft; and   the longitudinal length of said inner part of said second locking pin is longer than or at least equal to the rectilinear moving stroke of said second locking pin along said shaft.   
     
     
         6 . The coupler of  claim 1 , wherein:
 said first locking pin is tubular and said threads of said first tubular locking pin are formed at the internal surface of said first tubular locking pin; and   said second locking pin is tubular and said threads of said second tubular locking pin are formed at the internal surface of said second tubular locking pin.   
     
     
         7 . The coupler of  claim 1 , wherein:
 said threads formed at said shafts and said locking pins are multi start threads, whereby the lead per rotation is increased.   
     
     
         8 . The coupler of  claim 6 , wherein:
 said threads formed at said shafts and said locking pins are multi start threads, whereby the lead per rotation is increased.   
     
     
         9 . The coupler of  claim 1 , wherein said shaft further comprising:
 a driving section with a polygonal cross-section.   
     
     
         10 . The coupler of  claim 1 , further comprising:
 a fixture wrapping around said shaft and fixed to said bracket at its edges.   
     
     
         11 . The coupler of  claim 9 , further comprising:
 a first fixture wrapping around said shaft at the right side of said driving section and fixed to said bracket at its edges; and   a second fixture wrapping around said shaft at the left side of said driving section and fixed to said bracket at its edges.   
     
     
         12 . The coupler of  claim 1 , wherein:
 said first receiving slot has an outer wall with a first aperture receiving and securing the end of said first locking pin in the coupling position of the attachment; and   said second receiving slot has an outer wall with a second aperture receiving and securing the end of said second locking pin in the coupling position of the attachment.   
     
     
         13 . The coupler of  claim 1 , wherein:
 said first receiving slot has an outer wall with a first indentation receiving and securing the end of said first locking pin in the coupling position of the attachment; and   said second receiving slot has an outer wall with a second indentation receiving and securing the end of said second locking pin in the coupling position of the attachment.   
     
     
         14 . A coupler for detachably connecting an attachment to the free end of a lifting arm on a wheel loader, comprising:
 a bracket with a back face pivotally connected to said lifting arm and a front face detachably connected with said attachment;   a first and a second protrusions rearwardly extending from the lower back of said attachment and laterally spaced apart from each other, said first protrusion having a first locking hole pierced through its width and said second protrusion having a second locking hole pierced through its width;   a first and a second receiving slots formed at the lower front of said bracket and engaged with said first protrusion and said second protrusion, respectively;   a shaft which has threads formed at both ends and installed at the lower part of said bracket, wherein the threads formed at the one end of said shaft are right handed and the threads formed at the other end of said shaft are left handed;   a first locking pin which has threads corresponding to the threads formed at the one end of said shaft, a cross-section of said first locking pin being partially non-cylindrical shape, a contacting surface of said first locking hole with said first locking pin corresponding to said non-cylindrical contour of said first locking pin;   a second locking pin which has threads corresponding to the threads formed at the other end of said shaft, a cross-section of said second locking pin being partially non-cylindrical shape, a contacting surface of said second locking hole with said second locking pin corresponding to said non-cylindrical contour of said second locking pin; and   wherein said coupler has a coupling position of the attachment in which said locking pins are extended and engaged with said locking holes of said protrusions as said shaft rotates in one direction, and a release position of the attachment in which said locking pins are shortened and released from said locking holes of said protrusions as said shaft rotates in the other direction.   
     
     
         15 . The coupler of  claim 14 , wherein:
 the cross-section of said first locking pin is partially flattened cylindrical shape; and   the cross-section of said second locking pin is partially flattened cylindrical shape.   
     
     
         16 . The coupler of  claim 14 , wherein:
 the cross-section of said first locking pin is polygonal shape; and   the cross-section of said second locking pin is polygonal shape.   
     
     
         17 . The coupler of  claim 14 , wherein:
 said first locking pin is tubular and said threads of said first tubular locking pin are formed at the internal surface of said first tubular locking pin; and   said second locking pin is tubular and said threads of said second tubular locking pin are formed at the internal surface of said second tubular locking pin.   
     
     
         18 . The coupler of  claim 14 , wherein:
 said threads formed at said shafts and said locking pins are multi start threads, whereby the lead per rotation is increased.   
     
     
         19 . The coupler of  claim 14 , wherein said shaft further comprising:
 a driving section with a polygonal cross-section.   
     
     
         20 . The coupler of  claim 14 , further comprising:
 a fixture wrapping around said shaft and fixed to said bracket at its edges.   
     
     
         21 . The coupler of  claim 19 , further comprising:
 a first fixture wrapping around said shaft at the right side of said driving section and fixed to said bracket at its edges; and   a second fixture wrapping around said shaft at the left side of said driving section and fixed to said bracket at its edges.