Lead wheel steering system for a gantry crane

Details Lead wheel steering system for a gantry crane Lead wheel steering system for a gantry crane

1998-02-27

2001-03-27

Johnson, Brian L. (Department: 3618)

Motor vehicles

Having four wheels driven

With means for steering all driven wheels

C180S253000, C180S234000, C180S411000

Reexamination Certificate

active

06206127

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention generally relates to a directional control system for a gantry type crane which is drivable in longitudinal and transverse directions. More specifically, the invention relates to a steering control system which enhances steering control by automatically switching steering control to a “leading” pair of wheels.
Mobile gantry cranes are generally known for lifting, loading, and moving heavy loads and containers. Such cranes are commonly used at shipping yards, railyards, construction sites, etc. A gantry crane typically has four corner-mounted wheels.
So that a gantry crane can be desirably maneuvered and positioned over an object to be lifted, at least one pair of wheels of the crane is typically steerable. Transverse movement has been found to be desirable under certain lifting circumstances, and therefore, cranes are known in which all four wheels may be turned in a transverse direction for side-to-side movement. For example, U.S. Pat. No. 5,180,070 discloses a crane in which all four wheels may be turned in a transverse direction.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a steering system which enhances the maneuverability of a gantry crane.
The present invention achieves this and other objects by providing a steering system for a gantry crane which automatically switches steering control to the wheels of a “leading” pair of wheel assemblies, whether the crane is moving longitudinally frontwardly or rearwardly, or transversly right or left. More particularly, the system detects which pair of wheel assemblies are “leading” and sends steering control signals to the wheels of that that leading pair of wheel assemblies.
The system continues to deliver steering input signals from the operator controls only to the leading wheels until the leading direction of the crane is altered. For example, the system determines that a respectively different pair of wheels are “leading” when the operator reverses the drive direction or switches the general crane wheel alignment between longitudinal and transverse modes. The wheels of the pair of non-leading wheel assemblies are turned to, or held in, an appropriate straight alignment, as appropriate.
An advantage of the present invention is that it provides a steering system for a gantry type crane that enhances maneuverability.
Another advantage of the present invention is that it provides a steering system which automatically determines which pair of wheel assemblies are leading, and the system delivers steering motion control signals to the wheels of the then-leading wheel assemblies.
Additional features and advantages of the present invention are described in, and will be apparent from, the description of the invention herein, the claims, and the drawings.


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