Patent ID: 7370904

Claim:
A cover assembly mounted to the frame of a vehicle for covering an open top container mounted on the vehicle and having first and second ends, the cover assembly comprising; a retractable cover configured to overlay the open top of the container, a pair of pivot arms, each pivot arm having an upper and lower end, each pivot arm being pivotal at their lower end at a point intermediate the first and second ends of the container and adjacent a bottom of the container between a first position in which the upper ends of pivot arms are adjacent the first end of the container and a second position in which the upper ends are adjacent the second end of the container, means for varying a distance between the upper and lower ends of the pivot arms, a cross member extending between the upper ends of the pivot arms so that the pivot arms are connected together and to which one end of the retractable cover is attached, said means for varying a distance including a variable height assembly to which another end of the retractable cover is attached, the variable height assembly being mounted to the vehicle adjacent the first end of the container in a position such that when raised and lowered and while the pivot arms are in their first position, will increase and decrease the distance between the upper and lower ends of the pivot arms, means for raising and lowering the variable height assembly, means for maintaining a desired distance between the upper and lower ends of the pivot arms when the pivot arms are moved from the first position but for permitting the increase and decrease of distance between the upper and the lower ends of the pivot arms when the pivot arms are in their first position engaging the variable height assembly, the lower end of at least one of the pivot arms being connected to a hydraulic actuator mounted to the vehicle, the hydraulic actuator including spaced first and second ports, and means for supplying hydraulic pressure from a hydraulic reservoir relative to the first and second ports to operate the at least one hydraulic actuator to move the pivot arms between the first and second positions and that automatically releases hydraulic pressure from both ports of the at least one hydraulic actuator, simultaneously, to allow the pivot arms to pivot freely in either direction while the pivot arms are in their first position and the variable height assembly is raised and lowered.