Abstract: To reduce load on the operator and to establish traveling stability in the steering operation of a construction machine that has a pair of right and left traveling devices, and an engine as a driving power to the right and left traveling devices, a controller is provided which is responsive to a switch for traveling to drive or stop both a right and a left traveling devices. A switch for steering causes the controller to change the direction of travel of the construction machine, and the controller also acts to reduce the engine speed in accordance with the operation amount of the switch for steering.

Abstract: This invention provides to set plural test patterns in which two or more control valves are picked up from the plural control valves as diagnosis target, and there being installed a malfunction diagnosis means (47) in which the diagnosis of malfunctioned valve is applied to the test patterns as unit, and malfunction valve identification means (48) in which the malfunctioned valves are identified by checking the control valves one another, that control valves are included in the test patterns having been diagnosed whether malfunction exists or not by the malfunction diagnosis means (47).

Abstract: To reduce load on the operator and to establish traveling stability in the steering operation of a construction machine that has a pair of right and left traveling devices, and an engine as a driving power to the right and left traveling devices, a controller is provided which is responsive to a switch for traveling to drive or stop both a right and a left traveling devices. A switch for steering causes the controller to change the direction of travel of the construction machine, and the controller also acts to reduce the engine speed in accordance with the operation amount of the switch for steering.

Abstract: A control system for a machine is disclosed. The control system may have a bypass passage situated to allow fluid to bypass an actuator, and a warmup valve disposed within the bypass passage that is movable between flow-passing and-blocking positions. A controller is configured to move the warmup valve to the flow-passing position, fix a displacement position of the pump, compare the pressure of the fluid of the actuator with a threshold, and move the warmup valve to the flow-blocking position and reduce a pump outlet pressure when the pressure of the fluid is greater than the threshold. The controller may be configured to move the warmup valve to the flow-passing position, fix a displacement position of the pump, and adjust an input speed of the pump in response to the signal.

Abstract: This invention provides to set plural test patterns in which two or more control valves are picked up from the plural control valves as diagnosis target, and there being installed a malfunction diagnosis means (47) in which the diagnosis of malfunctioned valve is applied to the test patterns as unit, and malfunction valve identification means (48) in which the malfunctioned valves are identified by checking the control valves one another, that control valves are included in the test patterns having been diagnosed whether malfunction exists or not by the malfunction diagnosis means (47).

Abstract: A system for monitoring performance of a relief valve in a hydraulic system having a hydraulic actuator includes a supply discharge line fluidly coupled between a source of pressurized fluid and a fluid chamber of the actuator. The supply discharge line has a supply valve disposed therein. The system also includes a main relief line and a line relief line fluidly coupled to the supply discharge line. The main relief line includes a main relief valve and is disposed upstream of the supply valve while the line relief line includes a line relief valve and is disposed downstream of the supply valve. The line relief valve is configured to open at a pressure value greater than that used in the main relief valve. A controller compares fluid pressures in the main relief line and the line relief line to determine if the line relief valve is leaking.

Abstract: A hydraulic system is disclosed for use with. a machine. The hydraulic system may have an actuator, a valve associated with the actuator, at least one sensor configured to generate signals indicative of performance parameters of the hydraulic system, and a controller. The controller may be configured to determine at least one of a diagnostic movement and position of at least one of the fluid actuator and valve required to perform a health cheek, and to correlate the signals generated only during completion of the diagnostic movement or only when the at least one of the fluid actuator and valve are in the diagnostic position to values of the performance parameters. The controller may also be configured to make a comparison of the values of the performance parameters to expected values, and to determine a health of the hydraulic system based on the comparison.

Abstract: A control system for a machine is disclosed. The control system may have a bypass passage situated to allow fluid to bypass an actuator, and a warmup valve disposed within the bypass passage that is movable between flow-passing and-blocking positions. A controller is configured to move the warmup valve to the flow-passing position, fix a displacement position of the pump, compare the pressure of the fluid of the actuator with a threshold, and move the warmup valve to the flow-blocking position and reduce a pump outlet pressure when the pressure of the fluid is greater than the threshold. The controller may be configured to move the warmup valve to the flow-passing position, fix a displacement position of the pump, and adjust an input speed of the pump in response to the signal.