Abstract: A counterbalancing device includes a base and a main arm pivotally mounted to the base. The main arm resists a force acting thereon at a location remote from the axis, by virtue of a crank arm fixed to the main arm and supporting a cam follower, the latter located such that a hypothetical line from the axis to the follower is perpendicular to the direction of the main arm. A carriage moves with respect to the base and has a cam wall against which the follower bears, and a constant force spring provision is made to urge the cam wall against the follower in a direction which places a torque on the main arm so as to counterbalance the force. In a variant, a main arm has two ends and is pivotally mounted at a location between its ends to the base. First and second auxiliary arms are mounted respectively to the ends of the main arm, and the device is constructed such that the angle between the auxiliary arm directions is maintained constant.