Abstract: A travel control device for a work vehicle includes: a hydraulic pump; a plurality of hydraulic motors connected to the hydraulic pump in parallel through a closed-circuit connection, that drive different wheels with pressure oil delivered from the hydraulic pump; a slip detection device that detects a slip occurring at each of the wheels; and a flow control device that reduces, upon detection of a slip occurring at any of the wheels by the slip detection device, a quantity of pressure oil supplied to a hydraulic motor for driving the wheel at which the slip has been detected, among the plurality of hydraulic motors.

Abstract: A travel control device for a work vehicle includes: a hydraulic pump; a plurality of hydraulic motors connected to the hydraulic pump in parallel through a closed-circuit connection, that drive different wheels with pressure oil delivered from the hydraulic pump; a slip detection device that detects a slip occurring at each of the wheels; and a flow control device that reduces, upon detection of a slip occurring at any of the wheels by the slip detection device, a quantity of pressure oil supplied to a hydraulic motor for driving the wheel at which the slip has been detected, among the plurality of hydraulic motors.

Abstract: A travel drive system for a work vehicle includes: an HST drive device comprising a hydraulic pump driven by a prime mover and a hydraulic motor connected to the hydraulic pump by a closed circuit; an electric motor driven by using electric power generated by drive of the prime mover; a first drive wheel driven by the HST drive device; a second drive wheel driven by the electric motor; a vehicle speed detector that detects a vehicle speed; and a control unit that distributes output of the prime mover to the HST drive device and to the electric motor such that, as the vehicle speed detected by the vehicle speed detector increases, a proportion of a first power distributed to the HST drive device decreases and a proportion of a second power distributed to the electric motor increases.

Abstract: A hydro-static transmission travel system for a working machine enables the working machine to travel over a range from low speed to high speed with a simplified circuit arrangement. By referring to a machine traveling speed (vehicle speed) based on a detected signal from a rotation sensor, a controller computes respective target tilting amounts of hydraulic motors 10, 20 and controls the tilting amount for the hydraulic motors and a clutch. Depending on whether the traveling speed exceeds a setting speed as a reference boundary, the controller selectively switches over a drive mode between low-speed four-wheel drive, in which travel units 12, 22 are both driven, and high-speed two-wheel drive, in which the front-wheel side hydraulic motor 10 is controlled to zero displacement and only the rear-wheel side travel unit 22 is driven.

Abstract: A travel drive system for a work vehicle includes: an HST drive device comprising a hydraulic pump driven by a prime mover and a hydraulic motor connected to the hydraulic pump by a closed circuit; an electric motor driven by using electric power generated by drive of the prime mover; a first drive wheel driven by the HST drive device; a second drive wheel driven by the electric motor; a vehicle speed detector that detects a vehicle speed; and a control unit that distributes output of the prime mover to the HST drive device and to the electric motor such that, as the vehicle speed detected by the vehicle speed detector increases, a proportion of a first power distributed to the HST drive device decreases and a proportion of a second power distributed to the electric motor increases.

Abstract: A travel control device for a work vehicle includes: a hydraulic pump; a plurality of hydraulic motors connected to the hydraulic pump in parallel through a closed-circuit connection, that drive different wheels with pressure oil delivered from the hydraulic pump; a slip detection device that detects a slip occurring at each of the wheels; and a flow control device that reduces, upon detection of a slip occurring at any of the wheels by the slip detection device, a quantity of pressure oil supplied to a hydraulic motor for driving the wheel at which the slip has been detected, among the plurality of hydraulic motors.

Abstract: To permit smooth performance of both of an operation requiring a high pressure and an operation desired to produce a pressure at a suppressed level, a shuttle block positioned between pilot operating units and flow control valves and pump regulators is arranged in association with shuttle valves, which select maximum pressures of groups of operation signal pressures produced by the pilot operating units, respectively, and at least one of the plural groups of operation signals, and is constructed to include hydraulic selector valves and a boom-lowering, hydraulic selector valve that are operable in particular ways.

Abstract: The frame of a vehicle body is constituted by left and right vertical plates and a bottom plate coupling the vertical plates horizontally. In addition, a control valve device and a control valve device including a plural number of directional control valves are mounted in advance on a single mounting plate together with a correction lever, a plural number of operation levers and link mechanisms to obtain a lever/valve assembly. Then, the mounting plate constituting of the lever/valve assembly is attachable to or detachable from the left vertical plate of the frame by using bolts or the like. As a result, the efficiency of the assembly operation can be improved.

Abstract: A hydro-static transmission travel system for a working machine enables the working machine to travel over a range from low speed to high speed with a simplified circuit arrangement. By referring to a machine traveling speed (vehicle speed) based on a detected signal from a rotation sensor, a controller computes respective target tilting amounts of hydraulic motors 10, 20 and controls the tilting amount for the hydraulic motors and a clutch. Depending on whether the traveling speed exceeds a setting speed as a reference boundary, the controller selectively switches over a drive mode between low-speed four-wheel drive, in which travel units 12, 22 are both driven, and high-speed two-wheel drive, in which the front-wheel side hydraulic motor 10 is controlled to zero displacement and only the rear-wheel side travel unit 22 is driven.

Abstract: To keep one of three hydraulic pumps unaffected by variations in torque of the remaining hydraulic pumps when the three hydraulic pumps are used, displacements of the first and second hydraulic pumps are controlled based on their own delivery pressures P1,P2 and a pressure P3? obtained by reducing through a reducing valve 14 a delivery pressure P3 from the third hydraulic pump, while a displacement of the third hydraulic pump 3 is controlled only by its own delivery pressure P3. The pressure oil delivered from the third hydraulic pump 3, therefore, remains unaffected by variations in delivery flow rates from the first and second hydraulic pumps 1,2, in other words, by variations in their torque consumptions, so that the third hydraulic pump is assured to provide a stable flow rate.

Abstract: A device cover is formed as a whole in a bent L-shape by an upper face covering a device accommodation space from an upper side, a side face covering the device accommodation space from a right side, and a convex curved bent face connecting the upper face and the side face. In addition, the device cover is separated into an upper face separate cover element and a side face separate cover element at a joint position extending in a direction from the front toward the rear and then, these separate cover elements and are integrally connected by the use of a connecting plate.

Abstract: A joining directional control valve 13 is disposed to supply, to an arm cylinder 4, not only a hydraulic fluid delivered from a first hydraulic pump 1, but also a hydraulic fluid delivered from a second hydraulic pump 2 when an arm directional control valve 14 is driven. Respective delivery pressures of the hydraulic pumps 1, 2 are detected by pressure sensors 101, 102, and the opening area of a recovery control valve 6 is controlled depending on a lower one of the detected pressures from the pressure sensors 101, 102 such that, even in the combined operation of the arm cylinder 4 and another actuator 3, 4, the hydraulic fluid can be recovered for return to the arm cylinder 4 when the load pressure of the arm cylinder 4 is low. Thus, by supplying the hydraulic fluids from the two hydraulic pumps to the particular actuator for which the hydraulic fluid is to be recovered, a recovery flow rate is ensured when the load of the particular actuator is low in the combined operation.

Abstract: One of the mode lamps 38a, 38b and 38c of the mode indicator 38 corresponding to the current steering mode is turned on yellow and the other mode lamps are turned on green or turned off, thereby indicating whether front wheels 1, 1 and rear wheels 2, 2 are at neutral. A controller 39 does not operate a mode changing valve 24 even with an instruction outputted from a mode change switch 35 when the front and rear wheels are not at neutral, and operates, in response to an instruction outputted from the mode change switch 35, the mode changing valve 24 to establish a steering mode corresponding to the instruction when the front and rear wheels are at neutral. Also, the mode indicator 38 is controlled to always indicate, as the current steering mode, one corresponding to the steering mode actually established by the mode changing valve 24.

Abstract: To keep one of three hydraulic pumps unaffected by variations in torque of the remaining hydraulic pumps when the three hydraulic pumps are used, displacements of the first and second hydraulic pumps are controlled based on their own delivery pressures P1,P2 and a pressure P3? obtained by reducing through a reducing valve 14 a delivery pressure P3 from the third hydraulic pump, while a displacement of the third hydraulic pump 3 is controlled only by its own delivery pressure P3. The pressure oil delivered from the third hydraulic pump 3, therefore, remains unaffected by variations in delivery flow rates from the first and second hydraulic pumps 1,2, in other words, by variations in their torque consumptions, so that the third hydraulic pump is assured to provide a stable flow rate.

Abstract: To keep one of three hydraulic pumps unaffected by variations in torque of the remaining hydraulic pumps when the three hydraulic pumps are used, displacements of the first and second hydraulic pumps are controlled based on their own delivery pressures P1, P2 and a pressure P3? obtained by reducing through a reducing valve 14 a delivery pressure P3 from the third hydraulic pump, while a displacement of the third hydraulic pump 3 is controlled only by its own delivery pressure P3. The pressure oil delivered from the third hydraulic pump 3, therefore, remains unaffected by variations in delivery flow rates from the first and second hydraulic pumps 1,2, in other words, by variations in their torque consumptions, so that the third hydraulic pump is assured to provide a stable flow rate.

Abstract: To permit smooth performance of both of an operation requiring a high pressure and an operation desired to produce a pressure at a suppressed level, a shuttle block 50 positioned between pilot operating units 35-37 and flow control valves 5-15 and pump regulators 28a,28b is arranged in association with shuttle valves 61-63,65-75, which select maximum pressures of groups of operation signal pressures produced by the pilot operating units 35-37, respectively, and at least one of the plural groups of operation signals, and is constructed to include hydraulic selector valves 81,82 and a boom-lowering, hydraulic selector valve 83. The hydraulic selector valves 81,82 are operated based on the maximum pressures to produce control signal pressures from a pressure of a pilot pump 2.

Abstract: A joining directional control valve 13 is disposed to supply, to an arm cylinder 4, not only a hydraulic fluid delivered from a first hydraulic pump 1, but also a hydraulic fluid delivered from a second hydraulic pump 2 when an arm directional control valve 14 is driven. Respective delivery pressures of the hydraulic pumps 1, 2 are detected by pressure sensors 101, 102, and the opening area of a recovery control valve 6 is controlled depending on a lower one of the detected pressures from the pressure sensors 101, 102 such that, even in the combined operation of the arm cylinder 4 and another actuator 3, 4, the hydraulic fluid can be recovered for return to the arm cylinder 4 when the load pressure of the arm cylinder 4 is low. Thus, by supplying the hydraulic fluids from the two hydraulic pumps to the particular actuator for which the hydraulic fluid is to be recovered, a recovery flow rate is ensured when the load of the particular actuator is low in the combined operation.

Abstract: One of the mode lamps 38a, 38b and 38c of the mode indicator 38 corresponding to the current steering mode is turned on yellow and the other mode lamps are turned on green or turned off, thereby indicating whether front wheels 1, 1 and rear wheels 2, 2 are at neutral. A controller 39 does not operate a mode changing valve 24 even with an instruction outputted from a mode change switch 35 when the front and rear wheels are not at neutral, and operates, in response to an instruction outputted from the mode change switch 35, the mode changing valve 24 to establish a steering mode corresponding to the instruction when the front and rear wheels are at neutral. Also, the mode indicator 38 is controlled to always indicate, as the current steering mode, one corresponding to the steering mode actually established by the mode changing valve 24.

Abstract: A vehicular body oscillating mechanism (31) is provided between a frame (3) of an automotive vehicular body (2) and a stabilizer (18) thereby to sway the vehicular body (2) arcuately in a rightward and/or leftward direction about a pivot point (A) between right and left rear wheels (6, 7) when the stabilizer (18) is set on the ground for a load handling operation. This means that, after the stabilizer (18) is set on the ground for a load handling operation, the vehicular body (2) can be swayed arcuately laterally in a rightward and/or leftward direction together with a load lifting mechanism (12). Therefore, at the time of a load handling operation with the stabilizer (18) set on the ground for stabilization of the vehicular body (2), it is possible to turn and move the load lifting mechanism (12) into a rightward or leftward direction to adjust the position or direction of lifted freight goods in case it is deviated from a specified unloading spot in a lateral direction.

Abstract: A hydraulic drive system includes a hose rupture control valve unit 200 having a poppet valve member 5 serving as a main valve for opening and closing communication between a cylinder connection chamber 8 and a hose connection chamber 9, a spool valve member 6 disposed in pilot passages 15a, 15b connecting a back pressure chamber 10 and the hose connection chamber 9 of the poppet valve member 5. The spool valve member is operated by a pilot pressure supplied as an external signal and operates the poppet valve member 5, and a small relief valve 7 having the function of an overload relief valve. A check valve 39 is disposed in the pilot passage 15b for cutting off a flow of the hydraulic fluid from the hose connection chamber 9 to the back pressure chamber 10.