| 摘要 |
PROBLEM TO BE SOLVED: To automatically switch an "all-wheel drive system" and a "front wheel drive system" when mowing a lawn while descending a slope, in a riding-type lawn mower which is driven by a hydraulic motor individually installed at each wheel by using a single hydraulic pump. SOLUTION: In this lawn mower of a riding type for driving all the wheels hydraulically and driving each hydraulic motor MF, MB provided at each wheel WF, WB individually by one hydraulic pump A incorporated in a position for forming one driving loop circuit in a main pipe passage L<SB>0</SB>, a check valve V<SB>1</SB>, an automatic selector valve V<SB>2</SB>, and a relief valve V<SB>3</SB>are incorporated in a hydraulic circuit C<SB>1</SB>to switch the "all-wheel drive system" and the "front-wheel drive system" alternately by using a time immediately before the ground contact pressure of the rear wheel WB is reduced and the slip of the rear wheel WB is generated and a time when the slip of the rear wheel WB is not generated due to an increase of the ground contact pressure of the rear wheel WB as a reference. COPYRIGHT: (C)2008,JPO&INPIT
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