JPH0324589B

PURPOSE:To prevent the occurrence of response lag of a pressure regulator through prevention of bending of a link, by a method wherein a driving force responding to an operating mode by which the pressure regulator is actuated is outputted by varying the pressure collecting areas of the upper and the lower chamber of a pressure regulator servo motor. CONSTITUTION:A guide vane servo motor 1 and a pressure regulator 5 are intercoupled through a link mechanism 7, and a pressure regulator servo motor 6 is connected to the pressure regulator 5 so that it can actuate the pressure regulator 5 independently. The collecting areas of chambers on both sides of a piston 15 of the pressure regulator servo motor 6 are differed from each other by differing the sizes of rods 13 and 14 from each other. When the pressure regulator 5 is moved independently from the guide vane servo motor 1, a high output is produced, and the pressure regulator 5 is so formed as to be applied with a low load when the pressure regulator 5 is actuated following the vane servo motor 1. This prevents a link mechanism 7 from being bent when the pressure regulator 5 is moved following the servo motor 1, and improves its response.