Patent ID: 8020234

Claim:
A ramp assembly, comprising: (a) a ramp portion configured for reciprocating motion about a center of rotation between a stowed position, a deployed position, and a neutral position, wherein the ramp portion has a center of gravity, the center of gravity being located directly above the center of rotation when the ramp portion is in the neutral position; and (b) a counterbalance associated with the ramp portion, comprising: (i) a shaft configured to rotate (1) in a first direction when the ramp portion moves toward the stowed position, and (2) in a second direction opposite the first direction when the ramp portion moves toward the deployed position; (ii) a crank fixedly coupled to the shaft; (iii) a rod having a first end rotatably coupled to the crank about a first axis, the first axis moving along an arcuate path when the ramp portion reciprocates between the stowed position and the deployed position; and (iv) a cylinder coupled to a second end of the rod and coupled for rotational movement about a second axis, the second axis having a fixed location relative to the neutral position of the ramp portion, wherein the cylinder provides a force, (1) the force biasing the ramp portion toward the stowed position when the ramp portion is between the deployed position and the neutral position, and (2) the force biasing the ramp portion toward the deployed position when the ramp portion is between the stowed position and the neutral position.