Field of the Invention
This invention is generally directed to loading dock lifts and more specifically to safety barriers for such loading dock lifts.
Background of the Invention
Loading dock lifts have a variety of applications involving the transfer of cargo between an elevated truck bed and a depot floor. A typical loading dock lift includes a lift platform and apparatus for moving the lift platform between an upper position aligned with a truck bed and a lower position in which the lift platform is aligned with the depot floor. Cargo transfers during loading and unloading operations from the truck occur at a “front” side of the loading dock lift which is closely adjacent the truck bed. A “back” side of the lift platform is parallel to and spaced from the “front” side. When the lift platform is at a lowered position, cargo can be transferred between the depot floor and the lift platform at the back side. “Left” and “right” sides of the lift platform extend between the front and back sides of the lift platform, “left” and “right” being referenced when viewing the loading dock lifts from the back side of the lift platform toward the truck.
For purposes of this invention, “cargo” may comprise a variety of goods that have different sizes, shapes and weights. Generally speaking a lift platform is useful in elevating cargo from the depot floor to an upper level corresponding to a truck bed level to facilitate the transfer of freight onto the truck bed. That is, when freight is to be loaded onto a truck, the freight is transferred onto the lift platform over the back side at the ground or factory floor level. Then the lift platform and any cargo loaded on the lift platform elevates until the lift platform comes into an essentially coplanar alignment with the truck bed whereby cargo can transfer to the truck bed past the lift platform front side.
During an off-loading operation, an empty lift platform elevates to be in an essentially vertical alignment with the truck bed whereupon cargo can be moved from the truck bed onto the elevated lift platform past the front side. Then the loaded lift platform lowers to the factory floor level whereupon the cargo can be moved from the lift platform to the depot floor at the back side of the loading dock lift.
Personnel may ride on a loading dock lift during displacement of the lift platform. Consequently it is important that such loading dock lifts minimize the possibility of a person's sustaining an injury by making a misstep and possibly falling from the lift platform in an elevated position.
Many loading dock lifts include fixed side barriers along each side that prevent an individual from inadvertently walking off the lift platform along each side. When the upper surface of a lift platform is coplanar with the factory floor, there is little risk of personal injury by walking past the front side because the front side essentially is at the same level as the factory floor and is adjacent the truck bed. However, when the lift platform is elevated and absent a barrier across the back end of the lift platform, there is greater risk of personal injury due to a misstep because a person could fall along with the cargo being loaded on or off the truck at the back side of the lift platform.
Prior art lift platforms may include a barrier spanning the back side of the lift platform for providing protection during operations while the lift platform is being elevated or lowered or is at the elevated position. A common prior art approach uses a chain or other removable barrier that personnel attach and detach when the lift platform is lowered and attach prior to elevating the lift platform. However, such attaching and detaching steps constitute extra work that personnel may overlook while performing loading and unloading operations even recognizing that a failure to install this barrier poses a risk of injury. Consequently, such barriers along back side the lift platform still pose a risk to personnel of inadvertently walking off the lift platform while it is elevated.
Therefore it is an object of this invention to provide a safety gate for a loading dock lift that provides a barrier at any time the lift platform is elevated from the factory floor.
Another object of this invention is to provide a safety gate that closes automatically without effort by personnel.
Still another object of this invention is to provide a safety gate that is economical to install
In accordance with this invention a safety barrier for a loading dock lift includes a lift platform that moves between a bottom position and an upper position. The safety barrier comprises a sleeve attached to the lift platform extending along a vertical axis. A gate has a barrier attached to an upper portion of a shaft wherein a bottom portion of the shaft extends through and is rotatable within the sleeve. The sleeve includes a guide that is shaped to define open and closed positions of said gate and the shaft includes a pin at a position along the shaft that extends through the guide, wherein when a pin interacts with the guide in the closed position, the gate is closed and when the pin interacts with the guide in the open position, the gate can be opened.
The appended claims particularly point out and distinctly claim the subject matter of this invention. The various objects, advantages and novel features of this invention will be more fully apparent from a reading of the following detailed description in conjunction with the accompanying drawings in which like reference numerals refer to like parts, and in which:
Each of
The structures constituting the safety gates of this invention have similar construction except for modifications that will appear in the implementation of the left and right safety gates. In the following description it will be helpful to define a loading dock lift as having “front,” “back,” “left” and “right” sides. In the following description some corresponding components have the same reference numbers; however the letters “L” and “R” distinguish the components associated with the left and right safety gates, respectively. For example,
The figures show a barrier does exist at the back side of the platform. In accordance with this invention, this barrier comprises left and right safety gates 40L and 40R that are attached to the side barriers 30L and 30R, respectively. Support shafts 42L and 42R ride in sleeves 43L and 43R respectively for axial motion of the support shafts along a vertical axis of each sleeve between an uppermost axial position of the support shafts 42L and 42R when the lift platform 26 is at the position of
When the lift platform 26 begins to elevate, the shafts 42L and 42R remain in contact with the ground or floor 21 and undergo downward displacement relative to sleeves 43L and 43R, respectively, due to gravity. The shaft 42R interacts with the sleeve 43R to rotate the shaft 42R clockwise, when viewed from above, to close the safety gate 40L. As the lift platform 26 continues to rise, the shaft 42R lowers with respect to the sleeve 43R and the safety gate 40R is locked in a closed position. The safety gate 40L undergoes a similar process except the shaft 42L rotates counter-clockwise when viewed from above.
The lower portion of the vertical support shaft 42R extends downwardly to pass through the sleeve 43R that the bracket 44R supports in a vertical orientation. The bracket 44R also positions the sleeve 43R to be offset from the edge of the horizontal lift platform 26 such that the shaft 42R is free to slide vertically in the sleeve along an axis 55 without contacting the lift platform 26. In fact, when the gate is in the open position (e.g., the lift is in the lowered position), shaft 42R contacts the floor. When in the closed position (e.g., the lift is in the elevated position), shaft 42R slides vertically down axis 55 through sleeve 43R and the bottom of shaft 42R is not in contact with a surface and extends into the air. Referring to
In this embodiment, the guide 60 has a doglegged shape, but the guide can have any shape so long as it allows for vertical and rotational movement along the axis so that the gate can move from the closed position to the open position, and vice versa. Widened portion 65 or the tapered mouth (e.g., the upper portion of the dogleg) is formed by extension 62 and the top portion of vertical edge 61 and allows the user to open and close the gate because the pin 66 along with shaft 42R and barrier 41R can rotate 90° between the edges when the gate is in the open position and the lift is in the lowered position.
The first and second guides 60 and 70 are located oppositely in the sleeve 43R with the center line of the channels 63 and 73 being diametrically opposed. The pin 66 is supported by the shaft 42R and extends horizontally beyond the sleeve 43R so that the guides 60 and 70 control the angular position of the support shaft 42R.
Now referring to
Now referring to
As the lift platform 26 lowers to a position proximate the floor 21 whereupon, the bottom end 48R comes into contact with floor 21 and rises so that the pin 66 moves upward through the intermediate control section and into the widened areas 65 and 75. Typically the safety gate 40R remains in the closed position. Once the pin 63 is positioned in the widened areas 66 and 76, it is possible to manually pivot the barrier 40R between the closed and open positions. That is, a force applied by an individual to the barrier 40R will readily overcome any friction generated by contact between the bottom 48R and the floor 21. Consequently in this position an individual can elect to open the safety gate and close the safety gate.
A sleeve 143R mounts between the beams 150 and 151 and rotates with the gate 141R about a vertical axis defined by the sleeve 143R and the extension 156R.
Still referring to
In this embodiment, the sleeve 143R will have a second guide on the opposite side of the sleeve 143R. Like the embodiment of
As the lift platform 121 elevates from the position shown in
In this embodiment, the bracket includes a metal tab 149R. As the sleeve 143R moves downward the travel path defined by the guides 160 and 170, the vertical position of the sleeve 143R enables the gate 141R to clear the tab 149R.
As will now be apparent, the vertical displacement of the safety gate from an open position to a locked position as shown in
As will now be apparent, a safety gate for a loading dock lift constructed in accordance with this invention provides a safety gate that provides a barrier at any time the lift platform is elevated from a factory floor. Closing the safety gate occurs automatically without effort by personnel while the lift platform is proximate its bottom position. Moreover, it will be apparent that such a safety gate is economical to install.
This invention has been disclosed in terms of specific embodiments. It will be apparent that a number of modifications can be made to the specifically disclosed embodiments incorporating this invention. Therefore, it is the intent of the appended claims to cover all such variations and modifications as come within the true spirit and scope of this invention.
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