Hydraulic Driving Apparatus
AssigneeHitachi Construction Machinery Co., Ltd.
InventorsKazuhiro ITOH, Kazuhiro NUMAGUCHI
Life of this patent
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Abstract
A counter balance valve (71L) is located between a directional control valve (23) and a hydraulic motor (32L) and provided on the way of a pair of supply/discharge lines (25A, 25B). The counter balance valve (71L) allows a spool (72L) to be displaced axially based on a pressure difference between the supply/discharge lines (25A, 25B). The counter balance valve (71L) includes a communicating passage (73L) for communicating the supply/discharge lines (25A, 25B) when the displacement of the spool (72L) exceeds a predetermined amount (XCM), based on a pressure difference between the supply/discharge lines (25A, 25B). The communicating passage (73L) is provided in the spool (72L) of the counter balance valve (71L).
Claims3
A hydraulic driving apparatus comprising:
- a first hydraulic pump and a second hydraulic pump;
- a first hydraulic motor rotatively driven by pressurized oil from the first hydraulic pump;
- a second hydraulic motor rotatively driven by pressurized oil from the second hydraulic pump;
- a pair of first and second supply/discharge passages connecting the first hydraulic pump, a hydraulic oil tank and the first hydraulic motor;
- a pair of third and fourth supply/discharge passages connecting the second hydraulic pump, the hydraulic oil tank and the second hydraulic motor;
- a first directional control valve provided on the way of the first and second supply/discharge passages and switching the direction of the pressurized oil supplied and discharged between the first hydraulic pump, the hydraulic oil tank and the first hydraulic motor;
- a second directional control valve provided on the way of the third and fourth supply/discharge passages and switching the direction of the pressurized oil supplied and discharged between the second hydraulic pump, the hydraulic oil tank and the second hydraulic motor;
- a first counter balance valve located between the first directional control valve and the first hydraulic motor, provided on the way of the first and second supply/discharge passages and allowing a first spool to be displaced axially based on a pressure difference between the first and second supply/discharge passages;
- and
- a second counter balance valve located between the second directional control valve and the second hydraulic motor, provided on the way of the third and fourth supply/discharge passages and allowing a second spool to be displaced axially based on a pressure difference between the third and fourth supply/discharge passages, wherein
- the first counter balance valve includes a first communicating passage communicating the first and second supply/discharge passages when the displacement of the first spool exceeds a predetermined amount based on a pressure difference between the first and second supply/discharge passages, and
- the second counter balance valve includes a second communicating passage communicating the third and fourth supply/discharge passages when the displacement of the second spool exceeds a predetermined amount based on a pressure difference between the third and fourth supply/discharge passages.
Dependencies are inferred from the claim text.