Sewing-machine lifting mechanism incorporated in table - with counter-balancing spring-loaded parallel levers coupled together and to vertically travelling slide

摘要

The lifting mechanism is incorporated in a sewing-machine table, the sewing-machine being fixed upright to a slide travelling up and down in a vertical sides of a frame secured to the table. The weight of the machine is roughly counterbalanced by a pair of spring-loaded levers hinging in the frame and coupled to the slide at both sides. The levers are coupled together and parallel. They can each be coupled to the frame by a U-shaped torsion spring whose arms are shorter than the frame width and extend roughly horizontally. The longer arm of each spring is also the hinge axis for its respective lever.