PURPOSE: To improve the effect of vibration suppression and decrease vibration noises, by making a plunger of a pipe packed with granular or fibrous material.
CONSTITUTION: The plunger 7 of a hydralulic cylinder 6 coupled to a gondola 8 is made of the pipe 9 packed with a filler 12 made of sand grains or chips of metal material, wich are rubbed by one another. When a hydraulic pump 1 is driven by an electric motor 2 and pressure oil is thereby supplied to the hydraulic cylinder 6, the gondola 8 is moved up. When the hydraulic pump 1 is stopped and the pressure oil is discharged into an oil tank 5 through a flow control valve 3, the gondola 8 is moved down. The pulsating pressure, which is caused by the hydraulic pump 1 and the flow control valve 3 and transmitted to the pressure oil in the hydraulic cylinder 6 during the move-up of the gondola, and the pulsating pressure, which is caused by the flow control valve 3 and transmitted to the pressure oil in the hydraulic cylinder 6 during the move-down of the gondola, are damped by the mutual rubbing of the filler 12. Thereby, the purpose is attained
NAKAMURA ICHIROU
TAKENOSHITA MITSUAKI
SEGAWA YORIHIDE
