Dock leveler

Claim 2

A dock leveler comprising a fixed structure, a deck having one end pivoted to said structure for swinging up and down movement of its other end, a lip pivoted to said other deck end for movement with said deck and swinging movement relative thereto between outstanding and depending positions, a holding mechanism connected to said lip and deck to hold said lip in its outstanding position and release said lip to its depending position, lip extending means connected to said lip to move the latter to its outstanding position upon upward deck movement, said holding mechanism serving to hold said lip in its outstanding position upon said upward deck movement and downward return of said deck to a predetermined lower position, actuating means located for operative actuation of said holding mechanism to release said lip to its depending position upon said downward return of said deck to said predetermined lower position; said holding mechanism comprising a linkage swingable into and out of limited over-center position with said lip outstanding to positively retain the latter outstanding; said linkage comprising a pair of links having their adjacent ends pivotally connected together and having their distal ends respectively pivoted to said lip and deck, and stop means carried by one of said links and engageable with the other of said links to limit relative swinging movement to said over-center position; and said actuating means comprising an abutment located to displace said links out of their over-center position upon downward deck movement to said predetermined lower position.

Claim 3

A dock leveler according to claim 1, said lip extending means comprising a crank arm pivotally carried by said deck and operatively connected to said lip for swinging the latter upwardly upon pivotal movement of said crank arm, and operating means connected between said crank arm and structure to operate the lip extending means on upward swinging movement of said deck.

Claim 4

A dock leveler according to claim 1, said abutment comprising a leg depending from one of said links adjacent to said adjacent link ends for abutting engagement with the nether fixed structure to effect said displacement.

Claim 5

A dock leveler according to claim 1, said lip extending means comprising linkage means connected between said deck, fixed structure and lip to effect outstanding movement of the latter upon upward deck movement, said linkage means being resiliently biased to effect yieldable lip extension, and cam means operatively associated with said linkage means to hold the latter against said resilient biasing.

Claim 6

A dock leveler according to claim 4, said linkage means being freely telescopic in one direction to render said lip extending means ineffective to retract said lip.

Claim 7

A dock leveler according to claim 1, said lip extending means comprising linkage means connected between said deck, fixed structure and lip to effect positive outstanding movement of the latter upon upward deck movement to a predetermined upper position and positive retracing link movement upon downward deck movement to a predetermined lower position.

Claim 8

A dock leveler comprising a fixed structure, a deck having one end pivoted to said structure for swinging up and down movement of its other end, a lip pivoted to said other deck end for movement with said deck and swinging movement relative thereto between outstanding and depending positions, a holding mechanism connected to said lip and deck to hold said lip in its outstanding position and release said lip to its depending position, lip extending means connected to said lip to move the latter to its outstanding position upon upward deck movement, said holding mechanism serving to hold said lip in its outstanding position upon said upward deck movement and downward return of said deck to a predetermiNed lower position, actuating means located for operative actuation of said holding mechanism to release said lip to its depending position upon said downward return of said deck to said predetermined lower position; said lip extending means comprising linkage means connected between said deck, fixed structure and lip to effect positive outstanding movement of the latter upon upward deck movement to a predetermined upper position and positive retracing link movement upon downward deck movement to a predetermined lower position; and additional lip extending means comprising additional linkage means connected between said deck, fixed structure and lip to effect outstanding movement of the latter upon upward deck movement, said additional linkage means being resiliently biased to effect lip extension, and cam means operatively associated with said additional linkage means to hold the latter against said resilient biasing, said additional linkage means being freely telescopic in one direction to render said additional lip extending means ineffective to retract said lip.

Claim 9

A dock leveler comprising a fixed structure, a deck having one end pivoted to said structure for swinging up and down movement of its other end, a lip pivoted to said other deck end for movement with said deck and swinging movement relative thereto between outstanding and depending positions, a holding mechanism connected to said lip and deck to hold said lip in its outstanding position and release said lip to its depending position, lip extending means connected to said lip to move the latter to its outstanding position upon upward deck movement, said holding mechanism serving to hold said lip in its outstanding position upon said upward deck movement and downward return of said deck to a predetermiNed lower position, actuating means located for operative actuation of said holding mechanism to release said lip to its depending position upon said downward return of said deck to said predetermined lower position; said lip extending means comprising linkage means connected between said deck, fixed structure and lip to effect positive outstanding movement of the latter upon upward deck movement to a predetermined upper position and positive retracing link movement upon downward deck movement to a predetermined lower position; and additional lip extending means comprising additional linkage means connected between said deck, fixed structure and lip to effect outstanding movement of the latter upon upward deck movement, said additional linkage means being resiliently biased to effect lip extension, and cam means operatively associated with said additional linkage means to hold the latter against said resilient biasing, said additional linkage means being freely telescopic in one direction to render said additional lip extending means ineffective to retract said lip.

Claim 10

A dock leveler according to claim 7, said holding mechanism comprising a linkage swingable into and out of a limited over-center position with said lip outstanding.

Claim 11

A dock leveler according to claim 8, said linkage comprising a pair of links having their adjacent ends pivotally connected together and having their distal ends respectively pivoted to said lip and deck, and stop means carried by one of said links and engageable with the other of said links to limit relative swinging to said over-center position.

Claim 12

A dock leveler according to claim 9, said actuating means comprising an abutment located to displace said links out of their over-center position upon downward deck movement to a predetermined position.

Claim 13

A dock leveler according to claim 1, further comprising means for automatically returning said dock leveler to a substantially level position.

Claim 14

A dock leveler according to claim 11, wherein said means for automatically returning said dock leveler to a substantially level position comprising linkage means and a cam follower arm having a roller at one end and cam means for operatively returning said deck leveler to a positive, locked, and substantially level position.

Claim 15

A dock leveler according to claim 12, wherein said cam means is a ramp.

Claim 16

A dock leveler according to claim 12, wherein said cam follower arm is pivotally mounted intermediate the roller end and the other end of said cam follower arm.

Claim 17

A dock leveler according to claim 14, wherein said other end of said cam follower arm is pivotally connected to said linkage means.

Claim 18

A dock leveler according to claim 15, wherein said linkage means comprising a link pivotally connected to an arm cooperatively associated with said lip, and tension means connected to a fixed position and to an outer end of an arm fixed intermediate said follower arm, whereby upon said lip being dropped, said deck is returned to a positive, locked, level position.