An articulate vehicle comprises a first frame disposed at one of front and rear portions of the vehicle and a second frame disposed at the other of front and rear portions of the vehicle. The first frame supports a first transaxle apparatus supporting a first axle. The second frame supports a second transaxle apparatus supporting a second axle. Proximal ends of the frames with respect to the vehicle are coupled to each other through a coupling part so that the first and second frames are rotatable relative to each other around a vertical axis according to steering operation. An engine is mounted on the first frame. A first hydraulic motor is integrally assembled in the first transaxle apparatus so as to drive the first axle. A working vehicle is equipped at a distal side of the second frame with respect to the vehicle. A second hydraulic motor is integrally assembled in the second transaxle apparatus so as to drive the second axle. A hydraulic pump is mounted on either the first or second frame, drivingly connected to the engine, and fluidly connected to both the first and second hydraulic motors.
A hydrostatic propulsion system includes a hydrostatic circuit fluidly connecting left front and right front motors in parallel with an outlet of a pump, left rear and right rear motors in parallel with an inlet of the pump, left front motor and right rear motor in series, and the right front motor and left rear motor in series. A valve system has a first relief valve line providing flow from a right rear motor inlet side to a left rear motor inlet side, and a second relief valve line providing flow from a left rear motor inlet side to a right rear motor inlet side. A first check valve line provides flow from a right rear motor outlet side to the right rear motor inlet side, and a second check valve line provides flow from a left rear motor outlet side to the left rear motor inlet side.
A hydraulic four-wheel driving articulated vehicle comprises: a first frame, on which first axles and a first hydraulic motor driving the first axles are mounted; a second frame, on which second axles and a second hydraulic motor driving the second axles are mounted, wherein the first and second frames are connected to each other so as to be relatively rotatable centering on a vertical axis by a steering operation; a hydraulic pump; a hydraulic circuit fluidly connecting the first and second hydraulic motors in series to the hydraulic pump, wherein the hydraulic circuit includes a passage interposed between the first and second hydraulic motors; and pressure control means for releasing oil from the passage between the first and second hydraulic motors when the first and second frames are relatively rotated by the steering operation of the stationary vehicle and backpressure oil discharged from the first and second hydraulic motors is excessively accumulated in the passage between the first and second hydraulic motors.
An articulated vehicle with a working device has a first frame having a prime mover mounted thereon and supporting a first transaxle apparatus. The first transaxle apparatus includes an input shaft receiving power from the prime mover, a pair of first axles, and a hydrostatic transmission. The hydrostatic transmission comprises a variable hydraulic pump, a first hydraulic motor fluidly connected to the hydraulic pump via a fluid passage, and a housing with a flexible port fluidly connected to the fluid passage. The second transaxle apparatus includes a pair of second axles having different lengths and a second hydraulic motor. The second hydraulic motor is fluidly connected via piping to a directionally adjustable connection portion of the flexible port. Proximal ends of the first and second frames with respect to the vehicle are coupled to each other so that the first and second frames are rotatable around a vertical axis relative to each other when steered.
