PURPOSE: To make the steering operation of a body foldable type vehicle satisfactory, by connecting a steering operation mechanism to a discharge flow control mechanism for a variable displacement type pump to prevent the generation of cavitation in a passage on the discharge side of the variable displacement pump.
CONSTITUTION: A variable displacement pump 42 has one entrance/exit port 43 connected to the head side chamber 16 of a hydraulic cylinder 15 and to the rod side chamber of a hydraulic cylinder 17 through a passage 44, and another entrance/exit port 45 connected to the head side chamber 21 of the hydraulic cylinder 17 and to the rod side chamber 22 of the hydraulic cylinder 15 through a passage 46, and therefore, establishes a closed-loop circuit together with the hydraulic cylinders 15, 17 and passages 44, 46. Steering wheels 7 are connected through a link mechanism including a feed-back mechanism to a spool control section 57 in a servo control valve 56 which is disposed in a regulator 41 to control the port of a liquid chamber 48. Relief valves 58, 59 are disposed in the passages 44, 46 so that the variation rate of the discharge flow may be easily changed.
FUJIKAWA HIROSHI
SUZUKI SHIGERU
KONDOU KEISUKE
