Patent ID: 8691008

Claim:
An apparatus for measuring the weight of an object while pulling the object upward, the apparatus comprising: a frame having a vertical axis and a horizontal axis, the vertical axis parallel to an axis along which the object is pulled, the horizontal axis being orthogonal to the vertical axis; a cable connected to the object; a first cylinder rotatably mounted on the frame, at least a portion of the cable engaging a surface of the first cylinder; a second cylinder rotatably mounted on the frame, at least a portion of the cable engaging a surface of the second cylinder, the cable travelling along a cable path between the first cylinder and the second cylinder; an arm having a first end and a second end, the first end coupled to at least one of the frame and the second cylinder, the second end coupled to the first cylinder, the arm having a longitudinal axis substantially parallel to the cable path and connecting the first and second ends, wherein the arm substantially restrains the first cylinder from movement parallel to the horizontal axis; a force measurement device for measuring the weight of the object, the force measurement device coupled to the first cylinder; and an actuator operable to raise and lower the first cylinder such that the cable remains stationary with respect to the first cylinder while the object is pulled upward.