Drive unit for a moving part, especially the upper tool of a press brake, comprises two hydraulic cylinders controlled by a shift valve

摘要

Drive unit for a moving part (16) comprising a first hydraulic cylinder (34) connected the moving part, a second hydraulic cylinder (22) connected to an electric motor (10) through a threaded piston rod (14) and a shift valve (44) that controls the fluid supply to the second cylinder, where the outlet side of the second cylinder is in permanent fluid communication with the inlet side of the first cylinder.