FORWARD AND REVERSE GEAR CHANGE STRUCTURE OF TRACTOR

PROBLEM TO BE SOLVED: To lessen the member of pumps exerting a determined function in a forward and reverse gear change structure of a tractor where a forward clutch and a reverse clutch are selectively actuated to change over forwarding and reversing. SOLUTION: A forward and reverse selecting valve 51 selectively applying the oil pressure on either a forward clutch FC or a reverse clutch RC, a modulation mechanism 52 increasing oil pressure applied to the selected clutch with determined characteristics by use of a reducing valve, an inching mechanism 53 continuously regulating the oil pressure applied to the selected clutch from 0 pressure to the maximum pressure according to the treading amount of a pedal 20 and modulation characteristics changing mechanism 54 selectively changing the pressure increasing characteristics with a modulation mechanism to a plurality of specifications comprise a hydraulic unit 50 for forward and reverse changing, and also this hydraulic unit 50 is arranged in series to a hydraulic unit 30 for a power steering.