To improve the convenience in actual use even when an electric system is broken by providing an electric operation type sub-transmission in such a manner as to be operable to a plurality of shift states on the basis of an operating means different from a main transmission, and returning and energizing it to a set shift state in the state where no driving power is supplied.
This transmission system is provided with a hydrostatic continuously variable transmission 7 switchable to forward and backward, which is a main transmission, and a 3-stage shift type sub-gear shifting transmission mechanism 8. The continuously variable transmission 7 has a manual gear shifting lever 7L for shifting operation. A sub-transmission device FH is formed of the sub-gear shifting transmission mechanism 8, a shift control valve, and a neutral selector valve, and the shift control valve and the neutral selector valve are electric operation type switching means. This sub-transmission device FH is also constituted so as to be returned and energized to a standard speed that is a set shift state when an electric system is broken, so that a cutting work can be thereafter continued at a general traveling speed for cutting work.
OZAKI NORIMUNE
YAMAGATA KOJI
