Dockboard

Claim 2

A dockboard to be mounted on a dock, comprising a frame secured to the front surface of the dock, a ramp having a lower vertical storage position whereat the ramp is disposed along the front surface of the dock and having an elevated operating position whereat the ramp is located above the level of the dock and spans the distance between the upper surface of the dock and the bed of a carrier, guide means associated with the frame for guiding the ramp in vertical movement, a pair of scissor arms, a first end of a first of said arms being pivotally connected to the frame and the second end of said first arm being mounted for movement on said ramp, a first end of the second of said arms being pivotally connected to the ramp and the second end of said second arm being mounted for movement on said frame, the central portions of the arms being pivotally connected together, said arms being disposed in generally parallel relationship when the ramp is in its vertical storage position and said arMs being pivoted to a generally erect X-shaped configuration when the ramp is moved to its operation position, and spring means connected to the second end of one of said arms for urging said second end inwardly toward the first end of the other arm and thereby urging the arms to the generally erect X-shaped configuration.

Claim 3

The dockboard of claim 1, wherein said spring means comprises a first spring and a second spring, said first spring interconnecting the second end of the first arm and the ramp, said second spring interconnecting the second end of the second arm and the frame, said springs acting to urge the arms of the X-shaped configuration, and means responsive to the ramp being elevated to a given position above the lower vertical storage position for withdrawing the force of said first spring from the ramp so that only the force of said second spring acts to counterbalance the weight of the ramp.

Claim 4

The dockboard of claim 2, and including a third spring operably connected to the second end of the first arm and acting in conjunction with said first spring and said dockboard including means responsive to the ramp being elevated to a second predetermined position above the lower vertical storage position for withdrawing the force of said third spring from the ramp.

Claim 5

A dockboard to be mounted on a dock, comprising a frame, a guide structure connected to the frame, guide means mounted for movement with respect to said guide structure, a ramp pivotally connected to the guide means and having a vertical storage position in which the ramp is disposed vertically along the front surface of the dock with the upper edge of the ramp being below the upper surface of the dock and said ramp having an upper vertical position in which the lower end of the ramp is at an elevation above the bed of a carrier located in front of the dock whereby the ramp can be pivoted to a generally horizontal position and lowered to an operative position wherein the ramp spans the distance between the dock and he bed of the carrier, a pair of scissor arms, a first end of a first of said arms being pivotally connected to the frame and the second end of said first arm being mounted for movement on said ramp, a first end of the second of said arms being pivotally connected to the ramp and the second end of said second arm being mounted for movement on said frame, the central portions of said arms being pivotally connected together, said arms being disposed in generally parallel relationship when the ramp is in the vertical storage position and said arms being pivotable to a generally X-shaped configuration as the ramp is moved upwardly to its operative position, counterbalancing means operably connected to said scissor arms for urging the arms to the X-shaped configuration, said counterbalancing means serving to exert a counterbalancing force to counterbalance the weight of the ramp, and means responsive to a given amount of movement of the ramp from the storage position toward the upper position for decreasing said counterbalancing force.

Claim 6

A dockboard to be mounted on a dock, comprising a frame, a guide structure connected to the frame, guide means mounted for movement with respect to said guide structure, a ramp pivotally connected to the guide means and having a vertical storage position in which the ramp is disposed vertically along the front surface of the dock with the upper edge of the ramp being below the upper surface of the dock and said ramp having an upper vertical position in which the lower end of the ramp is at an elevation above the bed of a carrier located in front of the dock whereby the ramp can be pivoted to a generally horizontal position and lowered to an operative position wherein the ramp spans the distance between the dock and he bed of the carrier, a pair of scissor arms, a first end of a first of said arms being pivotally connected to the frame and the second end of said first arm being mounted for movement on said ramp, a first end of the second of said arms being pivotally connected to the ramp and the second end of said second arm being mounted for movement on said frame, the central portions of said arms being pivotally connected together, said arms being disposed in generally parallel relationship when the ramp is in the vertical storage position and said arms being pivotable to a generally X-shaped configuration as the ramp is moved upwardly to its operative position, counterbalancing means operably connected to said scissor arms for urging the arms to the X-shaped configuration, said counterbalancing means serving to exert a counterbalancing force to counterbalance the weight of the ramp, and means responsive to a given amount of movement of the ramp from the storage position toward the upper position for decreasing said counterbalancing force.

Claim 7

The dockboard of claim 4, wherein the ramp includes a guide track on its undersurface and extending in a direction between the side edges of the ramp, the second end of the first arm having a guide element disposed to ride on the guide track as the arms are moved between the parallel and X-shaped positions.

Claim 8

The dockboard of claim 5, wherein the guide track extends continuously between the side edges of the ramp, said guide means including a vertical guide member secured to each side edge of the ramp and disposed to move within the guide structure to guide the ramp in vertical movement, the ends of said track being connected to said vertical guide members and constituting a portion of said guide means.

Claim 9

The dockboard of claim 6, wherein the guide tack comprises a downwardly facing channel and said ramp is pivotally connected to said channel.

Claim 10

The dockboard of claim 5, and including a second guide track mounted on the lower poRtion of the frame and disposed in parallel spaced relation beneath the first guide track, the second end of the second arm having a guide element disposed to ride on the second guide track as the arms are moved between the parallel and X-shaped positions.

Claim 11

The dockboard of claim 5, wherein said guide elements are wheels.

Claim 12

The dockboard of claim 4, wherein said counterbalancing means comprises a first spring and a second spring, said first spring interconnecting the second end of the first arm and the ramp, said second spring interconnecting the second end of the second arm and the frame, said springs acting to urge the arms to the X-shaped configuration.

Claim 13

The dockboard of claim 10 and including means responsive to a given degree of angular movement between said arms in moving from the parallel position to the X-shape position for releasing the force of one of said springs, whereby the weight of the ramp is counterbalanced solely by the other of said springs.

Claim 14

The dockboard of claim 12, wherein the guideways and the guide members have a relative length such that the guide members will move upwardly out of registering engagement with the guideways when the ramp is in the upper vertical position, and said dockboard includes means for preventing displacement of the ramp in a direction toward and away from the dock when the ramp is in the upper vertical position.

Claim 15

The dockboard of claim 13, wherein the last named means includes a guide track mounted on the front wall of the dock, and a guide element connected to one of said arms and disposed to ride on the track.

Claim 16

The dockboard of claim 14, wherein the guide element is located at a level beneath the location of pivotal connection of the arms.

Claim 17

The dockboard of claim 18, and including second spring means connected to the upper end of the first arm for urging the upper end of said first arm toward the upper end of the second arm.

Claim 18

A dockboard to be mounted on a dock, comprising a frame, a pair of spaced vertical guideways mounted on the frame, a vertical guide member mounted for vertical movement in each guideway, a ramp having a pair of opposed side edges and a front edge and a rear edge, means for pivotally connecting the side edge portions of the ramp to the guide members whereby the ramp can be pivoted with respect to said guide members, said ramp having a vertical storage position in which the ramp is disposed vertically along the front surface of the dock with the upper edge of the ramp beong below the upper surface of the dock and said ramp having an upper vertical position in which the lower end of the ramp is at an elevation above the bed of the carrier, a pair of scissor arms, a first of said arms has its lower end pivotally connected to the frame and its upper end movable connected to the ramp, and the second of said arms has its lower end movably connected to the frame and its upper end pivotally connected to said ramp, and the central portions of said arms being pivotally connected together, said arms being disposed in generally parallel relationship when the ramp is in the vertical storage position and said arms being pivotable to a generally erect X-shaped configuration as the ramp is moved upwardly to its operative position, and spring means connected to the lower end of the second arm for urging the lower end of said second arm inwardly toward the lower end of said first arm and thereby urging the arms to the generally erect X-shaped configuration.

Claim 19

A dockboard to be mounted on a dock, comprising a frame, a pair of spaced vertical guideways mounted on the frame, a vertical guide member mounted for vertical movement in each guideway, a ramp having a pair of opposed side edges and a front edge and a rear edge, means for pivotally connecting the side edge portions of the ramp to the guide members whereby the ramp can be pivoted with respect to said guide members, said ramp having a vertical storage position in which the ramp is disposed vertically along the front surface of the dock with the upper edge of the ramp beong below the upper surface of the dock and said ramp having an upper vertical position in which the lower end of the ramp is at an elevation above the bed of the carrier, a pair of scissor arms, a first of said arms has its lower end pivotally connected to the frame and its upper end movable connected to the ramp, and the second of said arms has its lower end movably connected to the frame and its upper end pivotally connected to said ramp, and the central portions of said arms being pivotally connected together, said arms being disposed in generally parallel relationship when the ramp is in the vertical storage position and said arms being pivotable to a generally erect X-shaped configuration as the ramp is moved upwardly to its operative position, and spring means connected to the lower end of the second arm for urging the lower end of said second arm inwardly toward the lower end of said first arm and thereby urging the arms to the generally erect X-shaped configuration.