Abstract: A torque fastening system and method for applying torque to secure a fastener, includes actuating a torque tool to provide an initial command torque value to the servo drive of an electric motor for applying torque to a fastener. The initial command torque value is less than a target command torque value corresponding to a desired maximum target torque value entered by an operator. The torque fastening system operates at the initial command torque value to rotate a threaded fastener. Thereafter, in response to a spike in torque that corresponds to a decrease in motor speed, the torque tool output changes from the initial command torque value to a jump command torque value having a greater power value to increase torque applied by the torque tool to a fastener. The command torque value is ramped from the jump command torque value toward the target command torque value to increase the torque provided by the torque tool.

Abstract: Cushion chambers (8) disposed in the vicinity of both ends of a hydraulic cylinder (1) to throttle inflow or outflow of an operating oil caused by a piston (5) moving close to a piston stroke end, pressure sensors (16, 17) to detect pressures in the cushion chambers (8), and a control valve (13) disposed in a passage to supply/drain the operating oil to and from oil chambers (6, 7) of the hydraulic cylinder (1) for varying a flow amount of the operating oil are provided. A controller (9) varies an opening degree of the control valve (13) within a piston stroke end range based upon outputs of the pressure sensors (16, 17), adjusts a cushion pressure and controls a moving speed of the piston (5). Thereby deceleration degrees of the piston (5) can be freely adjusted within the piston stroke end range based upon a change of the operating conditions of the hydraulic cylinder (1).