| 摘要 |
PROBLEM TO BE SOLVED: To provide the easy steering operation of a hydraulic transmission-type working vehicle capable of communicating and cutting off the discharge ports of the left and right hydraulic pumps, and improving the straight-advancing characteristic by communicating the discharge ports in the straight-advancing operation of a working machine. SOLUTION: The discharge ports 18L, 18R and the intake ports 19L, 19R of left and right hydraulic pumps PL, PR are independently communicated and connected to left and right hydraulic motors ML, MR through left and right going and returning oil passages 20L, 20R, 21L, 21R to form left and right static hydraulic continuously variable transmissions TL, TR. When a steering wheel 9 is operated to a straight-advancing position, the left and right going oil passages 20L, 20R and the left and right returning oil passages 21L, 21R are communicated to one another, and the equal oil pressure is supplied to the left and right hydraulic motors ML, MR, so that the equal driving force is generated on the left and right travelling parts 1L, 1R, and the straight-advancing characteristic of a hydraulic transmission-type working vehicle can be improved. When the steering wheel 9 is operated to a position excluding the straight-advancing position, the communication of the left and right going oil passages 20L, 20R and the loft and right returning oil passages 21L, 21R are cut off, and the different oil pressure is supplied to the left and right hydraulic motors ML, MR to perform turning travelling.
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