Front-of-dock dockboard

• US 4,501,042 A
• Filed: 10/13/1981
• Issued: 02/26/1985
• Est. Priority Date: 01/07/1980
• Status: Expired due to Fees

• Current Assignee: Kelley Co., Inc. (Assa Abloy AB)
• Original Assignee: Kelley Company
• Inventors: DiFonzo, Mark A.
• Primary Examiner(s): Bonck, Rodney H.
• Application Number:
  US06/310,499
• Time in Patent Office: 1,232 Days
• Field of Search: 14/71.3, 14/71.1, 14/71.7, 403/379, 248/613, 187/94
• US Class Current: 14/71.3
• CPC Class Codes: B65G 69/2858 with weight counterbalancing means

Abstract

A dockboard to be attached to the front of a loading dock. The dockboard includes a deck plate, the side edges of which are pivotally connected to guide bars that are movable vertically within guideways formed in the upper portion of a rectangular frame. The frame is mounted for vertical movement within guides mounted on the front face of the loading dock, and the frame and deck plate are partially counterbalanced to an upper position by a counterweight mechanism that is connected to the frame through a synchronized chain drive. The deck plate is stored in a vertical position below deck level and, in use, is lifted to a raised position above dock level, pivoted to a substantially horizontal position and then lowered into engagement with the bed of a carrier located in front of the dock. The pivotal connection between the deck plate and the guide bars enables the deck plate to tilt diagonally as a load moves across the deck plate in the event that the bed of the carrier is not parallel to the upper surface of the dock. When the carrier moves from the dock, the deck plate will swing to a vertical position and the frame will lower by gravity to move the deck plate to the vertical storage position.

Claims

1. A dockboard to be mounted on a loading dock having an upper surface and a front wall, comprising a generally rectangular frame disposed adjacent the front wall of the dock, guide means for mounting the frame for vertical movement relative to the dock, a pair of elongated tubular guideways disposed on said frame adjacent the sides thereof, a guide bar mounted for sliding vertical movement within each guideway, and a deck plate pivotally connected to the upper ends of the guide bars, said deck plate being liftable vertically from a first vertical lower storage position in which the deck plate is disposed generally vertically along the front wall of the dock to a second higher vertical position where at the lower end of the deck plate is above a bed of a carrier disposed adjacent the front wall of the dock so that the deck plate can be pivoted about said guide bars to a generally horizontal position and lowered to a cross traffic position to span the distance between the dock and the bed of said carrier with the rear end of the deck plate supported on the dock and thr forward end of the deck plate supported on the carrier, the forward end of the deck plate being biased downwardly so that the deck plate will assume a generally vertical position when the carrier is removed from its location adjacent the front wall of the dock and said deck plate will descend by gravity to said storage position, the sliding connection of the guide bars to said frame permitting the deck plate to tilt as a load passs over the deck plate when in the cross traffic position.

2. The dockboard of claim 1, and including counterbalancing means connected to the frame for partially counterbalancing the weight of the deckplate.

3. The dockboard of claim 2, wherein said counterbalancing means comprises a weight, and a pair of chains interconnecting the weight and the side edges of said frame.

4. The dockboard of claim 3, and including a pair of rotatable sprockets mounted in spaced relation adjacent the upper edge of the dock, each sprocket being engaged with a chain, one end of each chain connected to said weight and the opposite end of each chain connected to the lower portion of said frame.

5. The dockboard of claim 4, and including a shaft to carry each sprocket, and means for interconnecting the shafts to provide synchronous movement of said chains as the weights move vertically.

6. The dockboard of claim 1, wherein said guide means is composed of a pair of vertical walls spaced in a front-to-rear direction, said dockboard including a guide roller mounted on each side of the frame and disposed to ride against the forward surface of the rear vertical wall of each pair.

7. A dockboard to be mounted on a loading dock, said dock having an upper surface and a front wall, comprising a supporting structure mounted on the front wall of the dock, a generally rectangular frame disposed adjacent the front wall of the dock, guide means for mounting the frame for vertical movement on said supporting strucure, an elongated guideway disposed adjacent each side edge of the frame, a guide bar mounted for free vertical movement in each guideway, a deck plate having a front edge and a rear edge and a pair of side edges, means for pivotally connecting the side edge portions of the deck plate to the respective guide bars, counterweight means disposed along the front wall of the dock, a pair of chains, a pair of sprockets mounted at the upper end of the supporting structure and engaged with the respective chains, one end of each chain being connected to said counterweight means and the opposite end of each chain belong connected to the lower portion of said frame, a shaft to carry each sproket, said shafts being in general axial alignment, a connecting member connecting the adjacent ends of the shafts together whereby the chains will operate in synchronization as the counterweight means moves vertically to prevent skewing of said frame in said guide means, and means for permitting limited relative axial movement between each shaft and the connecting member.

8. A dockboard to be mounted on a loading dock having an upper surface and a front wall, comprising a generally rectangular frame disposed adjacent the front wall of the dock, guide means for mounting the frame for vertical movement relative to the dock, a pair of elongated tubular guideways disposed on said frame adjacent the sides thereof, a guide bar mounted for free sliding vertical movement within each guideway, and a deck plate pivotally connected to the upper ends of the guide bars, said deck plate being liftable vertically from a first vertical lower storage position in which the deck plate is disposed generally vertically along the front wall of the dock to a second higher vertical position where at the lower end of the deck plate is above the bed of a carrier disposed adjacent the front wall of the dock so that the deck plate can be pivoted about said guide bars to a generally horizontal position and lowered to a cross traffic position to span the distance between the dock and the bed of said carrier with the rear end of the deck plate supported on the dock and the forward end of the deck plate supported on the carrier, the forward end of the deck polate being biased downwardly so that the deck plate will assume a generally vertical position when the carrier is removed from its location adjacent the front wall of the dock and said deck plate will descent by gravity to said storage position, the sliding connection of the guide bars permitting the deck plate to tilt as a load passes over the deck plate when in the cross traffic position, and counterbalancing means interconnecting one of said guide bars and the deck plate for partially counterbalancing the weight of the deck plate to enable the deck plate to be pivoted to said generally horizontal position with a lesser manual force.

9. The dockboard of claim 8, wherein said counterbalancing means comprises a gas spring, said gas spring including a cylinder connected to one of said deckplate and said guide member, and a piston member slidable within the cylinder and connected to the other of said deckplate and said guide member.

10. The dockboard of claim 9, wherein the gas spring is connected between the lower end of said guide member and the underside of the deck plate, being located forwardly from the pivotal connection of said deck plate to the upper ends of said guide members.

11. The dockboard of claim 10, including a connecting member interconnecting the lower end of said guide member and said gas spring, said connecting member having an extensible connection disposed to permit said gas spring when fully extended to move relative to said guide member and prevent over extension of said gas spring on continued pivotal movement of said deckplate.

12. The dockboard of claim 11, wherein said extensible connection comprises a slotted connection between said gas spring and said connecting member.