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Yanmar Co., Ltd.

Yammar Co., Ltd.

Katsunori Katou

Mizuya Matsufuji

Toshiyuki Miwa

Takeshi Hasebe

Yuji Kitasaka

A hydraulically driven traveling vehicle comprising a pair of right and left driving axles (driving sprockets) differentially connected to each other by a differential mechanism, the input section of the differential mechanism having the output rotation of traveling HST() transmitted thereto, both driving sprockets having mutually opposite two-flow output rotations separately transmitted thereto from a steering HST (), thereby effecting traveling driving and turning, electromagnetic solenoids () serving as output regulating devices for the traveling HST and the steering HST being provided so that the manipulated variables and directions of a speed change lever and a steering operation tool are converted into electric signals, on the basis of which electric signals the output current values of the electromagnetic solenoids are controlled, causing the respective output rotary speeds of the HSTs to correspond to the output current values.

Hydraulically driven traveling vehicle

A speed change mechanism ( ) constructed by connecting in tandem a hydraulic type speed change unit ( ) having a plurality of hydraulic clutches ( ) to be alternatively engaged and a hydraulic type speed change unit ( ) having a plurality of hydraulic clutches ( ) to be alternatively engaged, wherein a time-varying region (common slip region) is secured in which the two clutches slip in common such that during speed change, when the working hydraulic pressure in a clutch to be engaged is on its way to gradual increase, the working hydraulic pressure in a clutch to be disengaged lowers. This common slip region is made smaller during shift-down than during shift-up by a change in time-difference between the pressure increase start time for the clutch to be engaged and the pressure decrease start time for the clutch to be disengaged or by a change in the pressure decrease property of the clutch to be disengaged.

Method of controlling hydraulic pressure in speed change mechanism having hydraulic clutches

A speed change mechanism ( ) constructed by connecting in tandem a hydraulic type speed change unit ( ) having a plurality of hydraulic clutches ( ) to be alternatively engaged and a hydraulic type speed change unit ( ) having a plurality of hydraulic clutches ( ) to be alternatively engaged, wherein a time-varying region (common slip region) is secured in which the two clutches slip in common such that during speed change, when the working hydraulic pressure in a clutch to be engaged is on its way to gradual increase, the working hydraulic pressure in a clutch to be disengaged lowers. This common slip region is made smaller during shift-down than during shift-up by a change in time-difference between the pressure increase start time for the clutch to be engaged and the pressure decrease start time for the clutch to be disengaged or by a change in the pressure decrease property of the clutch to be disengaged, and is maintained constant irrespective of whether one or two hydraulic clutches are engaged and disengaged during speed change respectively or irrespective of a difference in engine rpm.

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Osaka, Japan

Katsunori Katou