Patent ID: 8737077

Claim:
A linkage device, comprising: a shell comprising two side plates and an upper plate interconnecting the two side plates; an active arm positioned under the upper plate and between the two side plates, the active arm being arranged horizontally and comprising a first slide rail inclined to a horizontal surface; a random arm positioned under the upper plate and between the two side plates, the random arm being arranged horizontally and comprising a second slide rail inclined to the horizontal surface, the second slide rail of the random arm having an inclined direction opposite to that of the first slide rail; a linkage lever arranged outside the shell, the linkage lever comprising a central portion pivoted to one of the side plates and two ends respectively pivoted to the active arm and the random arm; and at least two fixed poles, one of the at least two fixed poles sliding in the first slide rail of the active arm and another one of the at least two fixed poles sliding in the second slide rail of the random arm when the random arm and the active arm move longitudinally in two opposite directions; wherein the shell further comprises a rear plate contacting the two side plates and the upper plate, and a gap is defined at the joint of each side plate and the rear plate, an end portion of the random arm extending to the outside of the shell via the gap.