Lip lifting mechanism for a dock leveler

In a dock leveler having a ramp pivotably mounted for movement between a raised position and a lowered position;

• a lip pivotably mounted to the ramp for movement between an inoperative position and an extended operative position in which the lip forms an extension of a deck plate forming a part of the ramp;
• a selectively operable lifting mechanism for raising the ramp to its raised position from its lowered position for subsequent lowering of the ramp;
• and a toggle mechanism for moving the lip to its extended operative position upon movement of the ramp toward its lowered position from its raised position, the toggle mechanism comprising an axial lifting rod engageable with the lip via lug structure pivotably connected to the ramp adjacent the lip, a push bar defining first and second ends and being pivotably mounted to stationary structure toward its first end, a link pivotably mounted to the ramp for movement about a first pivot axis and pivotably mounted to the lifting rod for movement about a second pivot axis, and releasable engagement structure interposed between the link and the push bar toward the second end of the push bar for engaging the push bar with the lifting rod through the link when the link is in a lip lifting position in which the link and the lifting rod form a rigid toggle structure for moving the lip to its extended operative position upon lowering of the ramp;
• the improvement comprising a release arrangement for moving the link away from its lip lifting position to break the rigid toggle structure, comprising a trip member fixed to the ramp and movable therewith, the trip member being engageable with the push bar toward its second end when the ramp reaches a predetermined position during movement of the ramp toward its lowered position from its raised position, to cause engagement of the push bar with the link to move the link away from its lip lifting position, to break the toggle and to enable the lip to fall to its inoperative position from its extended operative position.

A lip lifting mechanism for a dock leveler having a ramp pivotably mounted for movement between a raised position and a lowered position, a lip pivotably mounted to the ramp for movement between an inoperative position and an extended operative position in which the lip forms an extension of a deck plate forming a part of the ramp, and a selectively operable lifting mechanism for raising the ramp to its raised position from its lowered position for subsequent lowering of the ramp, comprising:

• a push bar defining first and second ends, wherein the push bar is pivotably mounted toward its first end to a stationary structure;
• an axial lifting rod defining first and second ends, wherein the first end of the rod is pivotably mounted to a pivotable lug with which the lip is engageable;
• a link pivotably mounted to the lifting rod toward its second end for pivoting movement about a first pivot axis, and pivotably mounted to the ramp for pivoting movement about a second pivot axis, and wherein the second end of the push bar is located adjacent the link and movable relative to the link upon movement of the link caused by raising and lowering of the ramp;
• engagement structure between the link and the push bar for engaging the push bar with the link upon lowering of the ramp from its raised position toward its lowered position, wherein the engagement structure functions to move the link and the lifting rod into an over-center toggle position upon movement of the ramp toward its lowered position for moving the lip from its inoperative position and for maintaining the lip in its extended operative position, wherein the engagement structure between the link and the push bar is engageable at a location spaced from and out of alignment with a transverse axis interconnecting the first and second pivot axes of the link;
• and
• a release arrangement for moving the link from its lip lifting position to move the link and the lifting rod away from the over-center toggle position, comprising a trip member fixed to the ramp and movable therewith, the trip member being engageable with the push bar toward its second end when the ramp reaches a predetermined position during movement of the ramp toward its lowered position from its raised position, to cause engagement of the push bar with the link to move the link and the lifting rod away from the over-center toggle position and to enable the lip to fall to its inoperative position from its extended position.