HYDRAULIC DRIVE UNIT OF WHEEL-TYPE WORKING VEHICLE

PROBLEM TO BE SOLVED: To provide a hydraulic drive unit of a wheel-type working vehicle which can limit a traveling drive force according to the discharge pressure of a working device hydraulic pump while suppressing a frequency at which high pressure acts on a traveling hydraulic pump and a traveling hydraulic motor, and can change the upper limit of the traveling drive force on the basis of an intention of an operator.SOLUTION: When the total sum of the discharge pressure Pm of the traveling hydraulic pump 11 and the discharge pressure Pw of the working device hydraulic pump 50 is not smaller than a reference value, a push-away capacity of the traveling hydraulic pump 11 is controlled by supplying the discharge pressure Pm, Pw as pilot pressure to first and second pilot ports 66, 67 of a cutoff valve 61 so that the discharge pressure Pm of the traveling hydraulic pump 11 becomes low as the discharge pressure Pw of the working device hydraulic pump 50 becomes high. Pilot pressure Pc to a third pilot port 68 of the cutoff valve 61 is set by an effect that a controller 85 controls a pressure control valve 83 according an operation position of a dial 80, and by this, the start pressure Ps (reference value) of the cutoff valve 61 is set.