Bridges – Gangway – ramp – or dock leveler – Attached
Reexamination Certificate
2000-06-12
2002-09-03
Hartmann, Gary S. (Department: 3671)
Bridges
Gangway, ramp, or dock leveler
Attached
C014S069500
Reexamination Certificate
active
06442783
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a dock leveler with run-off barrier configuration. A dock leveler is a device designed to bridge the gap between a loading dock and the surface of a truck or trailer bed. Under most circumstances, the floor of the truck bed and the top of the loading dock are at unequal heights and most dock levelers known in the prior art can accommodate some degree of vertical range of mis-match in these elevations.
There are three main categories of dock levelers, namely, pit levelers, vertically stored levelers, and edge of dock levelers. Pit levelers are designed to reside in a formed pit in the dock and are usually designed to accommodate a comparatively large height mis-match between the top surface of a loading dock and the surface of a truck bed, as much as 12 inches or more in some cases. Pit levelers provide unobstructed access to the dock and tend to be more expensive to manufacture and install than other types of dock levelers.
Vertically stored levelers do not require as much concrete work when they are installed and can often accommodate as great a height mis-match as is the case with a pit leveler. The vertically stored leveler has severe shortcomings in that it is extremely expensive to install and with a vertically stored leveler in place, access to the dock face is unobtainable.
A third type of dock leveler is known as the edge of dock leveler and attaches to the face of the dock where it intersects with the surface of the dock. Edge of dock levelers are more economical to install than other types of levelers in that less concrete work is required and in a similar manner as a pit leveler, edge of dock levelers provide unobstructed access to the dock as desired such as for end loading of a truck. However, edge of dock levelers known in the prior art do have a limitation in that, as known, they have a limited ability to accommodate a severe height mis-match between the dock surface and truck bed surface, usually, no greater than around 5 inches.
Edge of dock levelers as they are known in the prior art typically consist of three primary components, the faceplate, the deck and the lip. The faceplate is stationary and solidly fixed to the dock face. The deck rotates around the faceplate, and the lip rotates around the opposite end of the deck. When stored, the deck is substantially horizontal and the lip is angled approximately 90 degrees with respect to the deck hanging downward by gravity. To use such an edge of dock leveler, the deck is rotated back engaging a mechanism readies the lip for extension. The deck is then rotated forward and the engaged mechanism causes the lip to rotate around the deck. The now extended edge of dock leveler rests on the truck bed creating the bridge for loading and unloading of the truck. As the lip rests on the truck bed, the mechanism disengages. To return the edge of dock leveler for another use, the deck is rotated back some amount and the lip falls. After the lip falls off the truck bed, the deck is rotated forward until it rests in the initial cycle orientation. If the truck pulls away from an extended edge of dock leveler, the leveler will fall back to the initial, stored configuration.
Edge of dock levelers are also known to employ other activation mechanisms. Often a counterbalance spring or counterweight mechanism is installed to lessen the force required to activate the leveler. Other methods include powering the unit with hydraulics, pneumatics, and/or electromechanical power. On both ends of a typical edge of dock leveler, bumpers are often provided that prevent a truck from impacting the leveler when in the stored position.
Usually, when stored, both pit levelers and edge of dock levelers provide unobstructed access to the dock. Sometimes this can be advantageous, such as when a truck is loaded to the extreme rear not allowing room for the lip of the leveler to rest on the truck bed. But often, the unobstructed access provided by traditional storage position of both prior art pit levelers and prior art edge of dock levelers can allow equipment to run off the dock. A dock is typically around 3½ feet off the ground and free fall from that distance can easily cause equipment damage, personal injury, or even death.
One type of edge of dock leveler has been mandated by the U.S. Postal Service for use on their loading docks and is often described as the “Post Office Model”. In such a device, the lip may be extended into the deck forming a short, nearly vertical barrier when the edge of dock leveler is in the stored position. This configuration prevents lightly loaded equipment such as, for example, postal carts, from running off the edge of the dock. One deficiency of the so-called “Post Office Model” is the fact that it does not have a stored position allowing unobstructed access to the dock surface. In particular, the closest thing to a stored position for the “Post Office Model” consists of the position in which it comprises a light capacity vertical barrier.
The following prior art is known to Applicant:
U. S. Pat. No. 3,486,181 to Hecker, Jr. et al. teaches a dockboard including a deck and a lip. In the stored position of the device, the lip is received between two plates. In that position, the deck portion is aligned in a common plane with the surface of the dock.
U. S. Pat. No. 3,636,578 to Dieter discloses a spring counterbalanced compact dockboard including a deck and a lip pivotably mounted together. Dieter does not teach any configuration in which the device may act as a barrier.
U. S. Pat. No. 3,974,537 to Ellis et al. teaches a lip extender for loading dock levelers that includes a deck and a lip pivotably mounted together including a toggle arm connected between the dock and the lip allowing the lip to drop onto the truck bed. Ellis et al. fail to teach a pivotable linkage having an over-center stop mechanism combined with a kick-out bar.
U. S. Pat. No. 4,065,824 to Ellis et al. teaches similar structure.
U. S. Pat. No. 4,665,579 to Bennett et al. teaches a counterbalancing mechanism for an edge-of-dock dockboard. Bennett et al. fail to teach or suggested a configuration in which their device may be used as a barrier.
U. S. Pat. No. 4,525,887 to Erlandsson et al. teaches a counterbalancing mechanism for the ramp of a dockboard. The Erlandsson et al. device includes only a short lip and does not include the over-center structure of the present invention.
U. S. Pat. No. 4,689,846 to Sherrod teaches a dock leveler apparatus including a deck and a lip pivotably mounted together. Sherrod fails to teach or suggest use of the device as a barrier nor does he teach the specific details of the linkages of the present invention.
U. S. Pat. No. 4,920,598 to Hahn discloses a dock leveler with automatic vehicle barrier. In Hahn, a device separate from the deck and lip may act as a vehicle barrier. This differs from the teachings of the present invention in which the deck and lip may be reconfigured to create the barrier. U. S. Pat. No. 5,040,258 to Hahn et al. is similar in that a structure separate from the deck and lip is employed as a vehicle barrier.
U. S. Pat. No. 4,935,979 to Walker et al. discloses a dock leveler operating apparatus in which the dock leveler includes a deck and a lip pivotably mounted together. A linkage such as a chain interconnects a leg pivotably attached to the deck. Walker et al. fail to teach or suggest use of their device as a barrier nor do they teach or suggest the linkages disclosed herein.
U. S. Pat. No. 5,157,801 to Alexander teaches a dock leveler having an automatically actuated vehicle barrier. In a similar manner to the Hahn patents, the vehicle barrier in Alexander consists of a structure that comprises a separate device from the structure and function of the deck and lip.
U. S. Pat. No. 5,195,205 to Cook discloses a dock leveler operating apparatus in which a handle is used to actuate the functions of the dock leveler. Cook fails to teach or suggest a configuration of the deck and lip thereof that operate as a barrier nor does he
Chirico Robert J.
Yoon Young Z.
Genquip Corporation
Hartmann Gary S.
Markovich Kristine
Spiegel H. Jay
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