DIRECT ACTING TYPE LOAD SENSING CONTINUOUSLY VARIABLE TRANSMISSION AND PANTOGRAPH TYPE JACK

摘要

PROBLEM TO BE SOLVED: To enlarge the relative movement speed range of a nut. SOLUTION: A nut 9 having the same pitch as that of a threaded shaft 7 is threadedly joined with the periphery of the threaded shaft 7 supported rotatably around a rotary axis K-K. The effective diameter of the nut 9 is increased to a value higher than that of the threaded shaft 7. A spring 14 for speed change is provided to energize the nut 9 approximately vertically to a rotary axis to bring the nut 9 into eccentricity from the threaded shaft 7. When an axial force is lower than a first shift load, rotation of the nut 9 is prohibited and a first operation state to prohibit rotation of the nut 9 and produce feed screw operation is maintained. When the axial force is increased to a value higher than a first shift load, the first operation state is shifted to a second operation state wherein rotation of the nut 9 is allowed and load sensing continuously variable speed change operation is produced.