Stroke length variation mechanism - has two primary cylinders moving with secondary cylinder and supplying this with oil

摘要

The mechanism comprises two primary cylinders and one secondary one, converting a linear movement with a fixed stroke, generated in one direction by a separate driving mechanism, into one of different length. The three cylinders are in a common plane, the secondary one (4) being situated centrally between the two primary ones (2,3) and are permanently secured together. The piston rods (5,6) of the primary cylinders are fixed to the frame and so cannot move, and the cylinders are moved together by the drive upwards, the secondary piston receiving oil from the primary cylinders and thus moving upwards in its cylinder. The total movement of the secondary piston rod (9) is the sum of that of the cylinders themselves and of the rod itself in its cylinder. The reverse stroke is effected by a hydraulic accumulator charged on the upward stroke, the secondary rod movement being for the same distance as on this stroke.