Dock leveling apparatus

Abstract

A loading dock leveling apparatus including a ramp pivotable about its rear end and having a pivotable lip on its forward end. Apparatus is provided for projecting the lip outwardly after the ramp is raised beginning when the ramp is walked down to provide that the lip will engage the bed of a vehicle to be loaded or unloaded. The projecting apparatus includes a knuckle joint which pivots to projecting position on the ramp upswing and which is subsequently pivoted by a lever to release the projecting apparatus during the walk down but before the ramp descends to the highest serviceable vehicle level. A lip lock is provided for holding the lip in its projected position until the lip rests on the bed of the vehicle to be unloaded or until the ramp passes well below dock level and the lip lock is disengaged by a lip lock release.

I claim: 
     
       1. Lip lock means for maintaining a pivotable lip of a pivotable ramp associated with a loading dock in projected position until released by (1) pivoting the lip to a position near parallel with the ramp or (2) pivoting the lip end of the ramp to a downwardly inclined position to engage a lip lock release means, comprising, parallel plates secured together and sandwiching therebetween a block, the plates each being longer than the block and spaced apart by a width greater than the width of the block whereby the block is longitudinally slidable between the plates,   means for securing the block in the space between the plates and the lower portion of the securing means comprising a bracket of a generally elongated shallow U-shape, the open end of the U-shaped bracket facing upward toward the lower edges of the plates, the bracket being attached to and slidable with said block,   the front end of the plates being pivotally connected to the lip and the rear end of the plates being unattached,   means associated with the .[.deck.]. .Iadd.ramp .Iaddend.for supporting a pin, said pin projecting through the space between the plates and the U-shaped bracket and thereby supporting the plates, the pin having a diameter less tnan the depth of the U-shaped bracket,   a groove in the lower surface of the block having an axis parallel to the pin and a depth greater than the radius of the pin, the groove being located to open downwardly into the open face of the U-shaped bracket at the end of the bracket most remote from the lip,   notches formed in the lower surfaces of each of the plates and of a depth greater than the radius of the pin, the notches in the two parallel plates having a common axis parallel with the pin,   surface means forming the .[.slots.]. .Iadd.notches .Iaddend.wherein the surface means nearest the lip is shaped for preventing the pin from being .Iadd.relatively cammed .Iaddend.from the .[.slots.]. .Iadd.notches .Iaddend.as a result of force exerted by the weight of the lip acting on the plates.   
     
     
       2. The lip lock means of claim 1 wherein the surface of the notches most remote from the lip slopes to a smaller notch depth away from the lip to thereby .Iadd.relatively .Iaddend.cam the pin out of the notches as the lip pivots toward a plane parallel with the ramp. 
     
     
       3. The lip lock means of claim 2 wherein the lip lock release means comprises means for blocking the descent of the plates relative to the descent of the pin. 
     
     
       4. The lip lock means of claim 3 wherein the U-shaped bracket is of a width greater than the width between the plates. 
     
     
       5. The lip lock means of claim 4 in combination with automatic lip projecting and release means for raising the lip relative to the ramp until the pin moves into the .[.slot.]. .Iadd.notch .Iaddend.and thereafter releasing the lip to be supported by the pin. 
     
     
       6. The lip lock means of claim 1 in combination with automatic lip projecting and release means for raising the lip relative to the ramp until the pin moves into the .[.slot.]. .Iadd.notch .Iaddend.and thereafter releasing the lip to be supported by the pin. 
     
     
       7. The lip lock means of claim 1 wherein the lip lock release means comprises means for blocking the descent of the plates relative to the descent of the pin. 
     
     
       8. In the combination of dock leveling apparatus associated with a loading dock which is designed for loading and unloading vehicles; the loading dock having a generally planer upper surface; the apparatus including a ramp having front and rear portions and pivotally mounted at its rear portion; means associated with the ramp for releasibly blocking the upward movement of the ramp; means for pivoting the ramp upward upon release of said blocking means; lip means pivotally attached to the front portion of the ramp, said lip .Iadd.means .Iaddend.being for bridging the gap between the ramp and a bed of a vehicle and for limiting the descent of the front portion of the ramp below said bed; means for limiting the angle of pivot of the lip means from approximately parallel with the ramp to about a downwardly extending right angle with the ramp; means for automatically pivoting the lip upwardly from its right angle position to a projected position following (a) release of the ramp blocking means and (b) the upward pivoting movement of the ramp and during subsequent downward pivoting movement of the ramp; the automatic lip pivoting means comprising a straight arm pivoted from both ends, one end being pivoted from the lip and the other end pivoting from a short bar, the short bar being pivotally anchored to a substrate, said substrate being stationary relative to said dock, projecting means extending from the bar intermediate its pivot points for limiting the pivoting of said bar toward the substrate and means for releasing the automatic lip pivoting means during the ramp descent while the front portion of the ramp is above the level of the dock; lip lock means for maintaining the lip in projected position after the automatic lip pivoting means is released and until (1) the front portion of the ramp descends below the level of the dock to engage lip lock release means (2) the lip is pivoted to a position near parallel with the ramp; the improvement comprising: the .[.projection.]. .Iadd.projecting .Iaddend.means extending from the bar .[.is.]. .Iadd.and .Iaddend.adjustable in length to cooperatively coordinate the release of the automatic lip pivoting means with the time .Iadd.that the .Iaddend.lip lock means is positioned to support the lip in .Iadd.a .Iaddend.projected position.   
     
     
       9. The combination of claim 8 wherein the lip lock means comprises parallel plates secured together and sandwiching therebetween a block, the plates each being longer than the block and spaced apart by a width greater than the width of the block whereby the block is longitudinally slidable between the plates, means for securing the block in the space between the plates and the lower portion of the securing means comprising a bracket of a generally elongated shallow U-shape, the open end of the U-shaped bracket facing upward toward the lower edges of the plates, the bracket being attached to and slidable with said block,   the front end of the plates being pivotally connected to the lip and the rear end of the plates being unattached,   means associated with the ramp for supporting a pin, said pin projecting through the space between the plates and the U-shaped bracket and thereby supporting the plates, the pin having a diameter less than the depth of the U-shaped bracket,   a groove in the lower surface of the block having an axis parallel to the pin and a depth greater than the radius of the pin, the groove being located to open downward into the open face of the U-shaped bracket at the end of the bracket most remote from the lip,   notches formed in the lower surfaces of each of the plates and of a depth greater than the radius of the pin, the notches in the two parallel plates having a common axis parallel with the pin,   surface means forming the notches whereby the surface means nearest the lip is shaped for preventing the pin from being cammed from the .[.slots.]. .Iadd.notches .Iaddend.as a result of force exerted by the weight of the lip acting on the plates.   
     
     
       10. The combination of claim 9 wherein the projection means extending from the bar is adjustable in length to cooperatively coordinate the release of the automatic lip pivoting means with the time the pin moves into the notches in the lip lock means. 
     
     
       11. The combination of claim 8 wherein the straight arm of the automatic lip pivoting means comprises coaxially mounted tubes, said tubes allowing an angular swing of the ramp greater than needed for the lip to rise above the truck bed, means biasing the tubes together. 
     
     
       12. The combination of claim 8 wherein the lip is pivoted from the ramp by hinge means and the ramp extends horizontally beyond the hinge means to guard the pivot axis against falling material, ice and the like which might impair the pivoting movement. .Iadd. 13. The combination of claim 8 wherein the lip lock means comprises support means carrying an elongated pin in underlying relationship to the ramp and lip,   an elongated plate having one end thereof pivotally supported to permit swinging movement thereof in a plane transverse to the axis of said pin disposed beneath the ramp and lip in longitudinally extending relationship thereto, said plate having formed therein a notch with an axis parallel to said pin and opening at a longitudinal edge of the plate for receiving said pin when the lip is pivoted to the projected position, said notch having surface means shaped to prevent the pin from being cammed from the notch as a result of force exerted by the weight of the lip,   a block disposed adjacent said plate in longitudinally slideable relationship thereto, and having formed therein a groove with an axis parallel to said pin and opening at an edge surface to receive said pin when aligned with the notch in said plate,   means securing said block in association with said plate to permit relative longitudinal displacement between said plate and block, said means including a U-shaped bracket secured to said block with the open end of said bracket facing toward the edge of said block at which the groove opens for retaining the pin in association with said block, said bracket being of a length and depth greater than said pin and secured to said block to permit relative displacement of said pin into and out of said groove and to permit relative longitudinal displacement of said pin along the aforesaid edge surface of said block between a position aligned with said groove and a position not so aligned. .Iaddend. .Iadd. 14. The combination of claim 13 wherein the lip lock release means comprises means cooperatively engageable with the lip lock upon pivoting of the lip end of the ramp to a downwardly inclined position to displace said plate and block relative to said pin for disengaging said pin from the respective notch and groove whereby said plate and block may be longitudinally displaced relative to each other and to said pin and permit downward swinging of the lip with respect to the ramp. .Iaddend..Iadd. 15. The combination of claim 13 wherein said plate and block are longitudinally displaced with respect to said pin by pivoting of the lip toward a projected position at which position said pin enters the notch and groove of the respective plate and block and the lip is thereafter supported in the projected position by said pin. .Iaddend..Iadd. 16. Lip lock means for maintaining a pivotable lip of a pivotable ramp associated with a loading dock in a projected position until released by (1) pivoting the lip to a position near parallel with the ramp or by (2) pivoting the lip end of the ramp to a downwardly inclined position to engage lip lock release means,   comprising in mechanically coupled relationship between the pivotable lip and ramp   support means carrying an elongated pin in underlying relationship to the ramp and lip,   an elongated plate having one end thereof pivotally supported to permit swinging movement thereof in a plane transverse to the axis of said pin disposed beneath the ramp and lip in longitudinally extending relationship thereto, said plate having formed therein a notch with an axis parallel to said pin   and opening at a longitudinal edge of the plate for receiving said pin when the lip is pivoted to the projected position, said notch having surface means shaped to prevent the pin from being relatively cammed from the notch as a result of force exerted by the weight of the lip,   a block disposed adjacent said plate in longitudinally slideable relationship thereto and having formed therein a groove with an axis parallel to said pin and opening at an edge surface to receive said pin when aligned with the notch in said plate,   means securing said block in association with said plate to permit relative longitudinal displacement between said plate and block, said means including the U-shaped bracket secured to said block with the open end of said bracket facing toward the edge of said block at which the groove opens for retaining the pin in association with said block, said bracket being of a length and depth greater than said pin and secured to said block to permit relative displacement of said pin into and out of said groove and to permit relative longitudinal displacement of said pin along the aforesaid edge surface of said block between a position aligned with   
     
     
        said groove and a position not so aligned. .Iaddend..Iadd. 17.  Lip lock means according to claim 16 wherein said plate and block include frictional engagement means whereby said block is displaced with said plate upon longitudinal displacement of said plate to the extent permitted by said U-shaped bracket in cooperation with said pin. .Iaddend..Iadd. 18. Lip lock means according to claim 16 wherein said notch has surface means to relatively cam the pin from said notch upon longitudinal displacement of said plate as a consequence of pivoting the lip from the projected position to a position near parallel with the ramp. .Iaddend. .Iadd. 19. Lip lock means according to claim 16 wherein said pin is supported by said ramp and said plate is pivotally connected to said lip. .Iaddend..Iadd. 20. Lip lock means according to claim 16 wherein said pin is horizontally disposed and said plate is disposed in overlying relationship to said pin and is supported thereon throughout longitudinal displacement of said plate, said plate and block having the respective notch and groove formed therein in downwardly opening relationship. .Iaddend..Iadd. 21. Lip lock means according to claim 16 wherein the lip lock release means comprises means cooperatively engageable with said plate and block upon pivoting of the lip end of the ramp to a downwardly inclined position to displace said plate and block relative to said pin for disengaging said pin from the respective notch and groove whereby said plate and block may be longitudinally displaced relative to each other and to said pin and permit downward swinging of the lip with respect to the ramp. .Iaddend..Iadd. 22. Lip lock means according to claim 16 wherein said plate and block are longitudinally displaced with respect to said pin by pivoting of the lip toward a projected position at which position said pin enters the notch and groove of the respective plate and block and the lip is thereafter supported in the projected position by said pin. .Iaddend.