Patent ID: 6050355
Filing Date: 2000-04-18
Classification: B62D

Abstract:
A compact crawler having a very low profile comprising:a. a frame defining a central vertical axis and a vertical longitudinal plane passing through the vertical axis, and comprising first and second side bars and a center bar therebetween, the center bar being substantially symmetrical about the frame longitudinal plane;b. first track means journaled in the first side bar and the center bar for propelling the crawler along a horizontal surface;c. second track means journaled in the second side bar and the center bar for cooperating with the first track means to propel the crawler along the horizontal surface, whereinthe frame further comprises a top plate that completely overlies the first and second track means;the first and second track means have respective first runs that engage the horizontal surface and respective return runs parallel to the first run; andthe top plate is spaced from the return runs of the first and second track means by approximately 0.25 inches to thereby aid the crawler to have a very low profile above the horizontal surface;d. means for driving the first and second track means independently of each other; ande. means for enabling the frame to rotate with respect to the heavy object comprisingcarrier means rotatable within the top plate for supporting the object, wherein:the carrier means comprises:i. a carrier rotatable on the top plate about the frame central vertical axis, the carrier having a periphery that defines a plurality of indentations; andii. a washer interposed between the carrier and the top plate; andlock means for selectively engaging the carrier means to present rotation thereof in the top plate and disengaging from the carrier means to enable rotation thereof in the top plate, wherein:the lock means comprises:i. a lock plate slidable within the top plate and having at least one protrusion that is complimentary to the indentations in the carrier periphery; andii. actuator means for selectively sliding the lock plate protrusion into an out of engagement with the carrier indentations,so that the crawler can move a heavy object along the horizontal surface, and so that the frame can rotate under the object when the lock plate is disengaged from the carrier means.