TRANSMISSION

PROBLEM TO BE SOLVED: To easily change specifications between a mode of having a hydraulic auxiliary driving wheel switching unit and a mode of having no such unit, in a transmission for storing a traveling system hydraulic switching unit and a hydraulic PTO clutch unit in a transmission case separated to the other side in the longitudinal direction of a vehicle from a driving source. SOLUTION: This transmission case has an opening capable of inserting a traveling system auxiliary output shaft on a first end wall on one side in the longitudinal direction of the vehicle opposed to the driving source, and a pair of first and second recessed parts directly or indirectly arranged so as to open to one side in the longitudinal direction of the vehicle on both sides in the vehicle width direction for sandwiching the opening, that is, the pair of first and second recessed parts for forming fluid-tight first and second blocking-up spaces by cooperating with a corresponding cover member, and is constituted so that the first blocking-up space stores a traveling system switching valve and a PTO switching valve, and the second blocking-up space stores an auxiliary driving wheel switching valve. COPYRIGHT: (C)2008,JPO&INPIT