GB1209308A - Improvements in and relating to counter-balance mechanism - Google Patents

Abstract

1,209,308. Counterbalancing. THORN LIGHTING Ltd. 13 March, 1968 [21 March, 1967], No. 13261/67. Heading B8B. A mounting for counterblancing an object comprises a lever for carrying the object, the lever having a supporting fulcrum point F and a point C to which a vertical constant pressure spring counterbalancing force is applied to support the weight of the object, one of the points being free to move in a horizontal direction. In the embodiment shown the lever comprises a parallel linkage arrangement, wherein the object is supported at the free end of an arm 7, the counterbalance force is applied downwardly to the free end C of an arm 5, the fulcrum F is formed by the junction of the other two arms 8, 9 forming the linkage. The fulcrum F is horizontally movable in a slot 2 in a frame and the point C is vertically movable in a slot 3 in the frame. In the embodiment of Fig. 4 (not shown), the fulcrum and counterbalancing points are interchanged, the fulcrum still being movable in a horizontal slot-the counterbalancing point still being movable in a vertical slot but with the spring force acting upwardly. The embodiments of Figs. 5 and 6 (not shown), are similar to the embodiments of Figs. 3 and 4 except that a pivoted link is interposed between the said counterbalance point and the said vertical slot. In the embodiments of Figs. 7 and 8 (not shown), the fulcrum point is pivoted directly to the frame and the counterbalance point includes a roller movable along either the top or the bottom of a horizontal plate at the top of a counterbalance spring loaded plunger, depending on the vertical sense of the counterbalance force required. In the embodiments of Figs. 9-11 (not shown), the fulcrum point is pivoted directly to the frame and the counterbalance force is applied to a plunger, pivotally connected to the counterbalance point on the lever and vertically movable in a horizontally slidable plunger. In the embodiments of Figs. 10 and 12 (not shown) the fulcrum point is pivoted to a horizontally movable plunger and the counterbalance point is pivoted to a vertically movable plunger through which the constant force is applied. The embodiments of Figs. 1 and 2 (not shown), include the use of a single arm lever having the counterbalance point movable along a vertical slot and positioned either at the end of the arm opposite to the object or intermediate the ends, the fulcrum point moving in a horizontal slot and positioned intermediate the lever ends or at said end of arm respectively.