Kabushiki Kaisha Komatsu Seisakusho

Satoru Nihsida

Shigeru Yamamoto

Kazushi Nakata

Shigenori Matsushita

Shu H Zhang

In an apparatus for controlling the vertical movement of a scraper blade (18) of a bulldozer, a four-position hydraulic control valve (12), having HOLD, UP, DOWN, and FLOAT positions, maintains the scraper blade in the FLOAT condition without requiring a detent mechanism, even when the three-position operation lever (1, 51) is released with the hydraulic control valve (12) in the FLOAT position. The operation lever (1, 51), having HOLD, UP, and DOWN positions, provides electrical signals to a controller (4) for actuating the hydraulic control valve (12) with pilot pressures provided via solenoid pilot valves (6, 7). A hydraulic cylinder (19), connected to the scraper blade (18), is actuated by hydraulic oil from the hydraulic control valve (12). A control device (2, 52), for generating an electrical signal for the FLOAT position and transmitting that electrical signal to the controller (4), is provided on the three-position operation lever (1, 51), so that the hydraulic control valve (12) is held at the FLOAT position in response to the electrical signal from the control device (2, 52).

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Osaka, Japan

Satoru Nihsida