Patent ID: 6390233
Filing Date: 2002-05-21
Classification: B66C,B66F

Abstract:
A method of operating an lifting apparatus including a first arm structure having a longitudinal axis; a connecting plate including a first attachment portion connected to the first arm structure; a second arm structure rotatably attached to the connecting plate at a first pivot point; a displacing link rotatably attached to the connecting plate at a second pivot point, wherein the first and second pivot points are in a second attachment portion of the connecting plate and wherein the first and second pivot points and a predetermined point on the longitudinal axis of the first arm structure are in a substantially triangular configuration; and a moving device connected between the displacing link and the second arm structure; said method comprising the steps of:activating the moving device to cause a range of motion of the second arm structure relative to the first arm structure; moving the displacing link; displacing the moving device relative to the first arm structure in response to and during only a portion of the range of motion of the second arm structure relative to the first arm structure; increasing the range of motion of the second arm structure relative to the first arm structure; and increasing a mechanical advantage for moving the second arm structure relative to the first arm structure.