A circle drive system with clutch protection in motor graders is disclosed. The circle drive system includes a hydraulic motor that is configured to receive a pressurized fluid and generate a torque for a rotation of a circle and a moldboard. The circle drive system also includes a gearbox to transfer the torque generated by the hydraulic motor to the circle. Further, the circle drive system includes a clutch connected to the hydraulic motor at one end and to the gearbox at another end. In addition, the circle drive system also includes a hydraulic circuit having a pressure relief valve to relieve the pressurized fluid supplied to the hydraulic motor when a pressure of the pressurized fluid exceeds a predefined threshold. The pressure relief valve thereby, limits the torque generated by the hydraulic motor to less than or equal to a torque capacity of the clutch.

A system and method for excavating an aggregate from below or beside a foundation through an access hole is provided. The system includes an air compressor and an air line fluidly coupled to the air compressor. The system further includes a valve disposed in fluid communication on the air line, and an end effector in fluid communication with the air compressor. The end effector extends between a first end coupled to one of the air line or the valve and a second end. The end effector is sized to fit through the access hole. The system further includes a nozzle coupled to the second end of the end effector.

A working machine includes: a plurality of hydraulic actuators including a high-load hydraulic actuator and a low-load hydraulic actuator whose hydraulic pressure for actuation thereof is lower than that of the high-load hydraulic actuator; a plurality of direction switching valves each of which switches a direction of a hydraulic fluid for a corresponding one of the hydraulic actuators, the plurality of direction switching valves including a low-load direction switching valve that switches a direction of hydraulic fluid for the low-load hydraulic actuator; and a dummy-load forming unit that forms a dummy load in the low-load direction switching valve to suppress a variation in an actuation speed of the low-load hydraulic actuator between a time when the high-load hydraulic actuator and the low-load hydraulic actuator are operated in combination and a time when the low-load hydraulic actuator is operated singly.

A work machine control system includes: a pump; a cylinder operating a working equipment element in a movable range based on hydraulic oil supplied from the pump; a first path connected to the pump; a second path branching from the first path; a control valve adjusting the flow rate of the oil supplied to the cylinder via the first path; a bleed valve adjusting the flow rate of the oil discharged to a tank via the second path; a sensor detecting a posture of the element in the range; and a control device outputting a first command for adjusting the flow rate of the oil supplied to the cylinder and a second command for adjusting the flow rate of the oil discharged to the tank when element is determined to be present in an end section of the range based on detection data of the sensor.

A control system for a work vehicle includes a controller. The controller acquires actual topography data indicating an actual topography to be worked. The controller determines a target design topography indicating a target trajectory of a work implement of the work vehicle based on the actual topography. The controller acquires an uneven surface parameter indicating the degree of surface unevenness of the actual topography. The controller changes the target design topography according to the uneven surface parameter.

A hydraulic system includes a first supply line connecting a boom control valve and a bottom side of a boom cylinder, a second supply line connecting the boom control valve and a rod side of the boom cylinder, a leveling switch valve having: a first operating position allowing a leveling operation of a working tool; and a first stopping position allowing the leveling operation to stop, a ride controller including: a ride-control switch valve connected to a branched fluid line branched from the first supply line; and an accumulator configured to perform an anti-vibrating operation for suppressing a pressure fluctuation of the boom cylinder, and a drain fluid line to discharge operation fluid in a downstream section extending from the leveling switch valve to the rod side of the boom cylinder in the second supply line when the leveling switch valve is switched to the first stopping position.

An upper revolving structure (4) of a hydraulic excavator (1) includes a revolving frame (7), a counterweight (8), an operator's seat (12), a right front cover (17B) disposed from the right side of the operator's seat (12) toward a front end side of the revolving frame (7), a control valve device (18), and an accumulator (21). An accumulator support device (23) is provided between the operator's seat (12) and the right front cover (17B), the accumulator support device (23) is configured by a box (24) providing the inside thereof for an accommodating space (25) and having an opening (26) and a lid member (28) mounted on the box (24) through a hinge member (29) and opened and closed between an open position at which the side of a free end (28D) opens the opening (26) and a closed position at which the side of the free end (28D) closes the opening (26), and the accumulator (21) is mounted on the lid member (28).

In a hydraulic system for a working machine, a controller is configured or programmed to increase an output-port pressure of one activation valve for one hydraulic device and an output-port pressure of another activation valve for another hydraulic device to a normal pressure higher than a preloading pressure from a state where the output-port pressure of the one activation valve is equal to the preloading pressure and the output-port pressure of the other activation valve is lower than the preloading pressure, by causing the output-port pressure of the one activation valve to be lower than the preloading pressure and increasing the output-port pressure of the other activation valve to the normal pressure.

A hydraulic system for a working machine includes hydraulic actuators actuated with hydraulic fluid delivered from a hydraulic pump, and control valves each of which is shiftable among shift positions to control a flowrate of hydraulic fluid flowing to the corresponding hydraulic actuator. Each control valve includes an input port, an output port, and a flowrate reduction section. When the control valve is shifted to a reduction position, the flowrate reduction section reduces a flowrate of the hydraulic fluid entering the input port and outputs the flowrate-reduced hydraulic fluid to the output port. At least one of the control valves includes a flowrate increase section. When the control valve is shifted to an increase position, the flowrate increase section outputs the hydraulic fluid having entered the input port to the output port at a flowrate larger than that of hydraulic fluid output by the flowrate reduction section.

A hydraulic system for operating a circle drive gear of a grading machine includes a pump configured to output pressurized fluid, a directional control valve fluidly coupled to the pump, a bidirectional hydraulic motor located downstream of the directional control valve and fluidly coupled to the directional control valve via hydraulic lines. The hydraulic motor has an output shaft that is configured to be rotationally driven by pressurized fluid output by the pump. Dual counterbalance valves may be disposed within the hydraulic circuit of the directional control valve and hydraulic motor such that any gearbox driven by the hydraulic motor is protected from external opposing forces. Accordingly, motion in the circle drive system is hydraulically locked at the beginning and release of a circle rotation command with the help of fluid pressure in the hydraulic lines.