Kubota Corporation

Junichirou Inoue

Masaaki Hama

A hydraulically operable transmission comprises change speed gears, a hydraulic clutch, and a hydraulic circuit for operating the change speed gears and hydraulic clutch. The hydraulic circuit includes a plurality of hydraulic actuators interlocked with the change speed gears, and a pilot type control valve for controlling the hydraulic actuators. An oil line leading to the hydraulic clutch includes a pressure increase adjustor for adjusting pressure increase characteristics when the hydraulic clutch is engaged. The pressure increase adjustor includes, arranged parallel to one another, a normally open first switch valve closable when a secondary hydraulic pressure exceeds a first set level, a normally closed second switch valve openable when the secondary hydraulic pressure exceeds a second set level higher than the first set level, and a restrictor. The first switch valve is urged toward an open position by a spring whose urging force is increased when the control valve is operated to a high speed range.

Growing community of inventors

Osaka, Japan

Junichirou Inoue