Bridges – Gangway – ramp – or dock leveler – Attached
Reexamination Certificate
1998-03-27
2001-04-17
Bagnell, David (Department: 3673)
Bridges
Gangway, ramp, or dock leveler
Attached
C014S069500
Reexamination Certificate
active
06216303
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to the field of dock levelers, and more particularly to dock levelers having support legs.
BACKGROUND OF THE INVENTION
Dock levelers are mounted on loading docks and are adapted to bridge the gap between the dock and the end of a vehicle (e.g., a truck) parked in front of the dock. The dock leveler enables material handling equipment, such as a fork lift, to move between the dock and the vehicle bed.
The typical dock leveler includes a supporting structure, which is mounted in a pit in the loading dock, and a ramp. The rear end of the ramp is pivotally attached to the supporting structure so that the ramp is movable from a horizontal position to a position within the working range of the ramp (e.g., between an upwardly inclined position and a downwardly declined position). Hinged to the front end of most ramps is an extension lip, which is movable between a downwardly hanging pendent position and an extended position where the lip forms an extension to the ramp. Typically, after a truck is parked in front of the loading dock in preparation for a loading operation, the ramp of the dock leveler is pivoted upwardly to allow the pendent lip to clear the vehicle bed and subsequently lowered. As the ramp is moved, the lip is pivoted outwardly from the pendent position to the extended position. As the ramp is lowered, the extended lip will engage the bed of the truck to provide support to the ramp.
Many dock levelers also include support legs that maintain the ramp in a substantially horizontal position when the ramp is not in use (i.e., when the dock leveler is not engaged with a truck bed). These legs can be retracted for servicing truck beds that are below dock level. Typically, a pair of support legs are pivotally attached to the ramp at or around the lip hinge area and extend downwardly to engage a supporting sub-frame. The support legs may be spring biased forwardly toward a supporting position, and may be retracted to a non-supporting position by one of several means.
Both manual and automatic mechanisms have been used to retract the support legs. Manual support leg retraction mechanisms require the operator to engage a mechanism, for example by pulling a chain, to retract the support legs as the ramp is being lowered. Automatic support leg retraction mechanisms typically retract the support legs as the lip of the dock leveler is extended. In this way, the support leg is always retracted when the lip engages a truck bed.
SUMMARY OF THE INVENTION
The present invention is directed to an improvement in dock levelers. More specifically, the invention relates to a mechanism and a method of controlling the movement of one or more support legs, and incorporates several features and advantages of manual and automatic support leg retraction mechanisms while avoiding some of their respective disadvantages.
One feature of the present invention is that the support legs may be automatically retracted to facilitate lowering the ramp for below dock level service. In this way, the dock leveler is less likely to stall at the horizontal position as a result of the operator forgetting to manually retract the support legs. Another feature of the present invention is that the support legs may be positioned in a supporting position when a truck bed is engaged by the lip for above dock level service. This feature limits the descent of the ramp if a truck pulls away unexpectedly. Yet another feature of the present invention is that a means is provided for accomplishing the above function that is relatively simple in construction and does not require, for example, sensor arms or acceleration sensitive mechanisms.
In one aspect, a dock leveler is provided having a ramp, a support leg for supporting the ramp, and an extension lip that is movably connected to the ramp. The support leg is capable of movement relative to the ramp from a supporting position to a retracted position, and the lip is movable to an extended position. Movement of the lip toward the extended position results in movement of the support leg from the retracted position to a supporting position.
In another aspect, the present invention provides a method of operating a dock leveler having a ramp, a support leg and a lip. The method includes the steps of raising the ramp above a resting position, retracting the support leg to a retracted position, contacting the lip with a vehicle, extending the lip to an extended position, and moving the support leg from the retracted position to a supporting position during the extending step.
In yet another aspect, the present invention provides a method of operating a dock leveler having a ramp and a support leg, the method including the steps of raising the ramp above a resting position, retracting the support leg to a retracted position, lowering the ramp into substantial alignment with the vehicle bed, and moving the support leg from the retracted position to a supporting position during the aligning step.
REFERENCES:
patent: 3368229 (1968-02-01), Pfleger
patent: 3835497 (1974-09-01), Smith
patent: 3858264 (1975-01-01), Kuhns et al.
patent: 3877102 (1975-04-01), Artzberger
patent: 3902213 (1975-09-01), Pfleger et al.
patent: 3921241 (1975-11-01), Smith
patent: 3995342 (1976-12-01), Wiener
patent: 4279050 (1981-07-01), Abbott
patent: 4328602 (1982-05-01), Bennett
patent: 4665579 (1987-05-01), Bennett et al.
patent: 4937906 (1990-07-01), Alexander
patent: 4974276 (1990-12-01), Alexander
patent: 5440772 (1995-08-01), Springer et al.
patent: 5475888 (1995-12-01), Massey
patent: 5481774 (1996-01-01), Hodges et al.
patent: 5657502 (1997-08-01), Ellis
patent: 2048210 (1980-04-01), None
Addie Raymond
Bagnell David
Kelley Company Inc.
Michael & Best & Friedrich LLP
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