Abstract: An automatic brake subsystem (24) includes second accumulators (25F, 25R), a front second line (28) and a rear second line (29), second brake valves (30F, 30R), a first solenoid switching valve (32), first shuttle valves (33F, 33R), and a controller 37. A second solenoid switching valve (34F) and a pressure sensor (35F) are provided in the front second line (28), and a second solenoid switching valve (34R) and a pressure sensor (35R) are provided in the rear second line (29). In a case where it is determined that each of the second brake valve (30F, 30R) is not performing normally based upon a pressure of a hydraulic fluid detected by each of the pressure sensors (35F, 35R) and an operating signal supplied to the first solenoid switching valve (32) or each of the second brake valves (30F, 30R), a controller 37 performs control to switch each of the second solenoid switching valves (34F, 34R).

Abstract: A hydraulic oil resupply device (40) is provided between first accumulators (15F, 15R) in a manual braking operation circuit (11) and a second accumulator (25) in an automatic brake circuit (24). The hydraulic oil resupply device (40) resupplies hydraulic oil accumulated in the second accumulator (25) to the first accumulators (15F, 15R) at the operating of a manual braking operation by an operator. This configuration can suppress a rising speed of a brake pressure at the manual operation braking from being slow. Accordingly, in a vehicular brake system, it is possible to enhance a braking capability by the manual braking operation and improve the reliability.

Abstract: A hydraulic oil resupply device (40) is provided between first accumulators (15F, 15R) in a manual braking operation circuit (11) and a second accumulator (25) in an automatic brake circuit (24). The hydraulic oil resupply device (40) resupplies hydraulic oil accumulated in the second accumulator (25) to the first accumulators (15F, 15R) at the operating of a manual braking operation by an operator. This configuration can suppress a rising speed of a brake pressure at the manual operation braking from being slow. Accordingly, in a vehicular brake system, it is possible to enhance a braking capability by the manual braking operation and improve the reliability.

Abstract: In a regenerative braking device of a dump truck comprising an engine, a first generator and a second generator driven by the engine, at least one travel motor driven by generated electric power of the first generator and at least one fan motor to which generated electric power of the second generator is inputted via a first rectifier circuit, the regenerative braking device comprises: a resistive element to which regenerating electric power from the at least one travel motor in regenerative braking is supplied and which is cooled by at least one fan driven by the at least one fan motor and converts electric energy into heat energy and dissipates heat; and a DC/DC converter that inputs a part of the regenerating electric power which is supplied to the resistive element to an output line of the first rectifier circuit via a second rectifier circuit.

Abstract: An automatic brake subsystem (24) includes second accumulators (25F, 25R), a front second line (28) and a rear second line (29), second brake valves (30F, 30R), a first solenoid switching valve (32), first shuttle valves (33F, 33R), and a controller 37. A second solenoid switching valve (34F) and a pressure sensor (35F) are provided in the front second line (28), and a second solenoid switching valve (34R) and a pressure sensor (35R) are provided in the rear second line (29). In a case where it is determined that each of the second brake valve (30F, 30R) is not performing normally based upon a pressure of a hydraulic fluid detected by each of the pressure sensors (35F, 35R) and an operating signal supplied to the first solenoid switching valve (32) or each of the second brake valves (30F, 30R), a controller 37 performs control to switch each of the second solenoid switching valves (34F, 34R).

Abstract: Provided is a clutch control device for a work machine capable of controlling a fan to an appropriate rotational speed. In the clutch control device for the work machine, a controller includes a target fan rotational speed calculation module that calculates a target fan rotational speed for the fan, a clutch characteristic curve storage module that stores a plurality of clutch characteristic curves, a clutch command calculation module that outputs with reference to a clutch characteristic curve a first clutch control signal corresponding to the target fan rotational speed, a feedback control module that output a second clutch control signal based on the difference between the target fan rotational speed and an actual fan rotational speed, and an adder that adds the first clutch control signal and the second clutch control signal to output a third clutch control signal.

Abstract: In a regenerative braking device of a dump truck comprising an engine, a first generator and a second generator driven by the engine, at least one travel motor driven by generated electric power of the first generator and at least one fan motor to which generated electric power of the second generator is inputted via a first rectifier circuit, the regenerative braking device comprises: a resistive element to which regenerating electric power from the at least one travel motor in regenerative braking is supplied and which is cooled by at least one fan driven by the at least one fan motor and converts electric energy into heat energy and dissipates heat; and a DC/DC converter that inputs a part of the regenerating electric power which is supplied to the resistive element to an output line of the first rectifier circuit via a second rectifier circuit.

Abstract: Provided is a clutch control device for a work machine capable of controlling a fan to an appropriate rotational speed. In the clutch control device for the work machine, a controller includes a target fan rotational speed calculation module that calculates a target fan rotational speed for the fan, a clutch characteristic curve storage module that stores a plurality of clutch characteristic curves, a clutch command calculation module that outputs with reference to a clutch characteristic curve a first clutch control signal corresponding to the target fan rotational speed, a feedback control module that output a second clutch control signal based on the difference between the target fan rotational speed and an actual fan rotational speed, and an adder that adds the first clutch control signal and the second clutch control signal to output a third clutch control signal.

Abstract: Front wheels (6L, 6R) a steering operation of which is possible by a steering mechanism (12) are mounted on a vehicle body (2). Steering cylinders (22L, 22R) of the steering mechanism (12) extend and contract in response to an operation of a steering handle (27) provided in a cab (5) to perform the steering operation of the front wheels (6L, 6R). The steering mechanism (12) is provided with a rotation angle sensor (28) for detecting a steering angle ? of the left front wheel (6L) and a proximity switch (29) for detecting whether or not the front wheel (6L) is in a straight-ahead state. A controller (30) determines that the rotation angle sensor (28) or the proximity switch (29) is abnormal when the steering angle (?) detected by the rotation angle sensor (28) is different from the detection result by the proximity switch (29).

Abstract: A body hoisting state display device to be mounted on a dump truck includes: an angle detection unit that detects a rotation angle of the body with respect to the frame; a seating detection unit that detects whether or not the body is seated on the frame; a calculation unit that causes an inclination angle of the body at which the body is rotated with respect to the frame from a seated state of the body to be calculated, based on the rotation angle detected by the angle detection unit, as a ratio to an angle of a rotatable range that is defined between the seated state and a state in which the hydraulic cylinder is stopped at the position short of the position at which the hydraulic cylinder is extended to the maximal extent; and a display control unit that causes the ratio of the inclination angle of the body that is calculated by the calculation unit to be displayed on a display screen.

Abstract: A loading platform is capable of tilting on a vehicle body. In accordance with a position of an operating lever for operating a hoist cylinder for tilting the loading platform and ON/OFF of a limit change switch operated by an operator, a running speed of the vehicle body is limited. If the loading platform is not seated and the limit change switch is OFF, the running speed is limited to a first speed limit or less which is low speed running. If the loading platform is not seated and the limit change switch is ON, when the operating lever is at a lowering position or a floating position, change of the speed limit to a second speed limit faster than the first speed limit is allowed. When the operating lever is at a raising or holding position, the change of the speed limit from the first speed limit is prohibited.

Abstract: A road surface management system is capable of detecting road surface conditions that tend to damage dump trucks and displaying the positions of such road surfaces. When the traveling speed of the dump truck is higher than or equal to a preset threshold value, the server judges whether or not each of the pressures of suspensions of the dump truck detected by pressure sensors is within a reference range which has been set corresponding to each suspension. The server judges that the road surface at the position of a dump truck is in a poor condition if one of the pressures of the four suspensions of the dump truck is judged to be outside the reference range and the remaining three pressures are judged to be within the reference range. The positions of the road surfaces judged to be in the poor condition are displayed on an indicator.

Abstract: A hoist cylinder for rotationally moving a vessel provided between a vehicle body and the vessel, and first and second directional control valves for controlling supply and discharge of a pressurized oil with respect to the hoist cylinder are provided. The first and second directional control valves have a neutral position, a raising position where the vessel is rotationally moved upward, a lowering position where the vessel is rotationally moved downward, and a floating position where free fall of the vessel is allowed by contracting the hoist cylinder by the weight of the vessel. A flow control valve is provided between the first directional control valve and a tank, which controls a flow rate of the pressurized oil discharged from the hoist cylinder into the tank when the first directional control valve is set at the floating position and the vessel freely falls due to its own weight.

Abstract: A road surface management system is capable of detecting road surface conditions that tend to damage dump trucks and displaying the positions of such road surfaces. When the traveling speed of the dump truck is higher than or equal to a preset threshold value, the server judges whether or not each of the pressures of suspensions of the dump truck detected by pressure sensors is within a reference range which has been set corresponding to each suspension. The server judges that the road surface at the position of a dump truck is in a poor condition if one of the pressures of the four suspensions of the dump truck is judged to be outside the reference range and the remaining three pressures are judged to be within the reference range. The positions of the road surfaces judged to be in the poor condition are displayed on an indicator.

Abstract: A body hoisting state display device to be mounted on a dump truck includes: an angle detection unit that detects a rotation angle of the body with respect to the frame; a seating detection unit that detects whether or not the body is seated on the frame; a calculation unit that causes an inclination angle of the body at which the body is rotated with respect to the frame from a seated state of the body to be calculated, based on the rotation angle detected by the angle detection unit, as a ratio to an angle of a rotatable range that is defined between the seated state and a state in which the hydraulic cylinder is stopped at the position short of the position at which the hydraulic cylinder is extended to the maximal extent; and a display control unit that causes the ratio of the inclination angle of the body that is calculated by the calculation unit to be displayed on a display screen.

Abstract: Front wheels (6L, 6R) a steering operation of which is possible by a steering mechanism (12) are mounted on a vehicle body (2). Steering cylinders (22L, 22R) of the steering mechanism (12) extend and contract in response to an operation of a steering handle (27) provided in a cab (5) to perform the steering operation of the front wheels (6L, 6R). The steering mechanism (12) is provided with a rotation angle sensor (28) for detecting a steering angle ? of the left front wheel (6L) and a proximity switch (29) for detecting whether or not the front wheel (6L) is in a straight-ahead state. A controller (30) determines that the rotation angle sensor (28) or the proximity switch (29) is abnormal when the steering angle (?) detected by the rotation angle sensor (28) is different from the detection result by the proximity switch (29).

Abstract: A loading platform is capable of tilting on a vehicle body. In accordance with a position of an operating lever for operating a hoist cylinder for tilting the loading platform and ON/OFF of a limit change switch operated by an operator, a running speed of the vehicle body is limited. If the loading platform is not seated and the limit change switch is OFF, the running speed is limited to a first speed limit or less which is low speed running. If the loading platform is not seated and the limit change switch is ON, when the operating lever is at a lowering position or a floating position, change of the speed limit to a second speed limit faster than the first speed limit is allowed. When the operating lever is at a raising or holding position, the change of the speed limit from the first speed limit is prohibited.

Abstract: A hoist cylinder for rotationally moving a vessel is provided between a vehicle body and the vessel, and first and second directional control valves for controlling supply and discharge of a pressurized oil with respect to the hoist cylinder are provided. The first and second directional control valves have a neutral position, a raising position where the vessel is rotationally moved upward, a lowering position where the vessel is rotationally moved downward, and a floating position where free fall of the vessel is allowed by contracting the hoist cylinder by the weight of the vessel. A flow control valve is provided between the first directional control valve and a tank, which controls a flow rate of the pressurized oil discharged from the hoist cylinder into the tank when the first directional control valve is set at the floating position and the vessel freely falls due to its own weight.

Abstract: A diagnostic information presenting apparatus comprises sensors 40, etc. for detecting status variables regarding operating status or ambient environments of a construction machine, and a controller 2 for outputting, to a display unit 50, a basic data display signal to display basic data necessary for an initial screen 100 in accordance with detected signals from the sensors 40, etc., and for outputting, to the display unit 50, an alarm display signal or a failure display signal to present alarm display or failure display in accordance with alarm information regarding the status variables detected by the sensors 40, etc. or failure information from the sensors 40, etc. This enables information regarding an abnormality in the construction machine to be presented to an operator with an alarm in the least necessary way without giving nuisances to the operator.

Abstract: An engine protection system for a construction machine can individually diagnose the exhaust temperature specific to each cylinder of an engine corresponding to an engine revolution speed in order to find an abnormal condition of each engine cylinder in advance. A revolution speed sensor 14 detects revolution speed of an engine mounted in the construction machine and, a plurality, e.g., 16, cylinder temperature sensors 20a-20p detect exhaust temperatures of respective cylinders of the engine. A data recording unit 26 and a display controller 24 store the detected engine revolution speed and the detected exhaust temperatures of the respective cylinders. Trend data, which is produced based on the stored data, is sent to an office via a portable terminal and the display controller 24 outputs, a signal for playing back and displaying snapshots based on the stored data to a display unit 23 disposed in the cab 5.