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1. (WO2010122951) HYDRAULIC DRIVE DEVICE

Pub. No.:    WO/2010/122951    International Application No.:    PCT/JP2010/056793
Publication Date: Fri Oct 29 01:59:59 CEST 2010 International Filing Date: Sat Apr 10 01:59:59 CEST 2010
IPC: F04B 49/00
E02F 9/22
F04B 1/20
F15B 11/00
Applicants: KAYABA INDUSTRY CO., LTD.
カヤバ工業株式会社
ITO, Kazumi
伊藤 和巳
Inventors: ITO, Kazumi
伊藤 和巳
Title: HYDRAULIC DRIVE DEVICE
Abstract:
A hydraulic drive device (100) comprises a variable displacement main piston pump (20) and a variable displacement sub piston pump (50) which are rotationally driven through a common drive shaft (25, 55). The hydraulic drive device (100) is provided with: main hydraulic actuators (7, 8) for gradually reducing the discharge capacity of the main piston pump (20) according to rises in the discharge pressures (P1, P2) of the main piston pump (20); and a sub hydraulic actuator (10) for switching the discharge capacity of the sub piston pump (50) in two stages according to a rise in the discharge pressure (P3) of the sub piston pump (50). The configuration enables the capacity of the main piston pump (20) to be fine-adjusted and prevents the load on the pumps of the hydraulic drive device (100) from excessively increasing.