Patent ID: 7533481

Claim:
An excavator thumb assembly for use with an excavator having a boom with a longitudinal axis, a hydraulic cylinder, a hydraulic cylinder shaft that extends and retracts from the hydraulic cylinder, and a bucket pivotally attached to an end of the boom and operatively attached to the hydraulic cylinder shaft, the excavator thumb assembly comprising: a thumb pivot plate attached to an intermediate portion of the boom and including a thumb attachment point positioned above the longitudinal axis of the boom; a thumb pivotally attached to the thumb attachment point along a thumb pivot axis, and operatively attached to the hydraulic cylinder shaft in a manner that causes the thumb to pivot relative to the boom as the hydraulic cylinder shaft extends and retracts; and a cam having a pin at one end for connecting the cylinder shaft and a bucket linkage arm connecting the bucket and an actuator connecting the thumb at one end and the cam at the other end; whereby the cylinder shaft when retracted widens a distance between the bucket and the thumb and when the cylinder shaft is extended the distance between the bucket and the thumb is narrowed for grabbing an object; wherein the actuator is connected between the thumb and the cam, whereupon a motion of the cylinder shaft causes the bucket and the thumb to move toward and away from each other; and wherein the actuator is oriented in generally perpendicular relationship with respect to the thumb when the cylinder shaft is extended and the actuator is disposed at an obtuse angle with respect to the thumb when the cylinder shaft is retracted.