A working machine includes a prime mover, a traveling pump to be driven by the prime mover to output operation fluid, a traveling motor to be driven by the operation fluid outputted from the traveling pump and to change a motor speed between a first speed and a second speed higher than the first speed, a machine body on which the prime mover, the traveling pump, and the traveling motor are arranged, a traveling switching valve to be switched between a first state allowing the traveling motor to rotate at the first speed and a second state allowing the traveling motor to rotate at the second speed, and a controller to reduce a revolving speed of the prime mover based on a traveling condition of the machine body in switching the traveling switching valve between an accelerating state to switch the traveling switching valve from the first state to the second state and a decelerating state to switch the traveling switching valve from the second state to the first state.

Provided is a construction machine that can prevent a machine body from being lowered since a blade is not put into a float state even where a misoperation is made by an operator when the machine body is in a jacked-up state, and that can perform a favorable leveling operation by putting the blade into the float state in accordance with an operator's operation when the machine body is not in the jacked-up state. A hydraulic excavator includes a controller 42 that determines whether or not the machine body is in a jacked-up state and controls a float valve 41. In the case where it is determined that the machine body is not in the jacked-up state, the controller 42 changes over the float valve 41 to a float position V and invalidates an operation of a blade control valve 22, in accordance with a float instruction. In the case where it is determined that the machine body is in the jacked-up state, the controller 42 holds the float valve 41 in a reference position IV and validates the operation of the blade control valve 22, irrespectively of the presence or absence of the float instruction.

A controller unit is included in a liquid-pressure driving system for use in a working machine configured to supply an operating liquid to an actuator to move a structural body by the actuator. The controller unit includes: a gyro sensor configured to output a signal corresponding to an operation velocity of the structural body; and a controller configured to control a flow rate of the operating liquid supplied to the actuator, based on the signal output from the gyro sensor and corresponding to the operation velocity of the structural body, wherein: the controller is attached to the structural body; and the gyro sensor is incorporated in the controller.

A control method of a work machine includes: calculating a maximum flow rate of hydraulic oil discharged from a hydraulic pump; calculating a first target speed of working equipment including a bucket based on an operation amount of an operation device operated for driving a plurality of hydraulic actuators to which the hydraulic oil discharged from the hydraulic pump is supplied to drive the working equipment and a distance between the bucket and a target excavation landform; calculating a second target speed of the working equipment based on the maximum flow rate, and the operation amount of the operation device and the distance between the bucket and the target excavation landform; and outputting a control signal for controlling the hydraulic actuators based on a smaller one of the first target speed and the second target speed.

A work machine includes an elevating cab and processing circuitry. The processing circuitry is configured to detect the position of the elevating cab and to maintain a travel speed at low speed when a traveling operation is performed while the detected position of the elevating cab is higher than a predetermined height.

This disclosure relates to a hydraulic system for a hydro-mechanical machine comprising a rotary mechanism. The hydraulic system includes a primary accumulator configured to receive and store high-pressure fluid in response to stopping of the rotary mechanism. A control system coupled to the primary accumulator through a hydraulic supply circuit is configured to enable passage of the high-pressure fluid stored in the primary accumulator to a rotary control valve configured to control the rotary mechanism, through the hydraulic supply circuit, based on a predefined pressure threshold associated with the primary accumulator. A secondary accumulator coupled to the primary accumulator and the control system via the hydraulic supply circuit is configured to store surplus high-pressure fluid provided by the primary accumulator through the hydraulic supply circuit.

According to an aspect of the present invention, an information output method for a construction machine executed by one or more hardware processors includes detecting the condition of an inspection target of the construction machine with an information obtaining device. The cumulative operating time of the inspection target or the diagnosis result of the condition of the inspection target is determined based on the detection result. A maintenance price associated with the cumulative operating time or the diagnosis result is determined and output.

An articulated work vehicle has front and rear frames coupled. The work vehicle includes a hydraulic actuator driven by hydraulic pressure to change a vehicle body frame angle of the front frame with respect to the rear frame, a lever rotatable to change the body frame angle, a control valve that controls a flow rate of oil supplied to the hydraulic actuator, and a controller. The controller sets a target angle of the vehicle body frame angle with respect to an input angle of the lever, and controls the control valve such that an actual angle of the vehicle body frame angle matches the target angle of the vehicle body frame angle.

A hydraulic circuit (11) of a hydraulic excavator (1) is provided with a main hydraulic circuit (11A) including a boom cylinder (5D), a pilot hydraulic circuit (11B) for operating the boom cylinder (5D) and a recovery hydraulic circuit (11C) including an accumulator (29). In this case, the recovery hydraulic circuit (11C) is provided with a recovery control valve (31) that recovers pressurized oil discharged from the boom cylinder (5D) to the accumulator (29), a main supply control valve (34) for supplying pressurized oil accumulated in the accumulator (29) to the main hydraulic circuit (11A) and a pilot supply control valve (37) for supplying pressurized oil accumulated in the accumulator (29) to the pilot hydraulic circuit (11B).

A working machine includes a hydraulic device, an operation valve to supply operation fluid to operate the hydraulic device and to vary the operation fluid to be supplied to the hydraulic device, an operation device having an operation member supported swingably, the operation device being configured to output an operation signal in accordance with an operation amount of the operation member, and a controller including a swing calculator to calculate an evaluation value representing a degree of swinging of the operation member, and a control signal generator to generate a control signal based on the evaluation value and the operation signal.