Abstract: A steering device for a wheel loader includes a handle for steering, a lever for steering, a steering cylinder, a steering valve that controls a direction of operating fluid to the steering cylinder, and a pump that supplies operating fluid to the steering cylinder via the steering valve. The steering device further includes a handle control valve that controls the supply direction of the operating fluid according the handle, a lever electromagnetic control valve that controls the supply direction of operating fluid according to the lever, and a handle prioritization valve that shuts off a pilot hydraulic pressure supplied from the lever electromagnetic control valve to the steering valve according to a pressure produced by operating fluid flowing through the handle control valve when the handle is operated. Communication between the lever electromagnetic control valve and the steering valve is allowed when only the lever electromagnetic control valve is operated.

Abstract: A steering device for a wheel loader includes a handle for steering, a lever for steering, a steering cylinder, a steering valve that controls a direction of operating fluid to the steering cylinder, and a pump that supplies operating fluid to the steering cylinder via the steering valve. The steering device further includes a handle control valve that controls the supply direction of the operating fluid according the handle, a lever electromagnetic control valve that controls the supply direction of operating fluid according to the lever, and a handle prioritization valve that shuts off a pilot hydraulic pressure supplied from the lever electromagnetic control valve to the steering valve according to a pressure produced by operating fluid flowing through the handle control valve when the handle is operated. The handle prioritization valve includes a switching valve and a priority control valve switchable between a handle stage and a lever stage.

Abstract: A steering device for a wheel loader includes a handle for steering, a lever for steering, a steering cylinder, a steering valve that controls a direction of operating fluid to the steering cylinder, a pump that supplies operating fluid to the steering cylinder via the steering valve, and a return oil passage connected to a tank. The steering device further includes a handle control valve that controls the supply direction of the operating fluid according the handle, a lever electromagnetic control valve that controls the supply direction of operating fluid according to the lever, and a handle prioritization valve that shuts off a pilot hydraulic pressure supplied from the lever electromagnetic control valve to the steering valve according to a pressure produced by operating fluid flowing through the handle control valve when the handle is operated. The handle prioritization valve includes a throttle arranged in the return oil passage.

Abstract: The disclosed rotating parking brake control device obviates the need for an operator to operate an emergency-stop switch. A hybrid controller, to which a brake is connected, outputs a drive control signal to a rotating electric motor to control drive of an upper rotating body and also controls the brake by generating a brake release command signal and outputting the brake release command signal to the brake. A pump controller also generates a brake release command signal, and the brake release command signal generated by the pump controller is transmitted to the hybrid controller through an inter-controller signal line. The brake release command signal is outputted to the brake only when the brake release command signal is generated by the hybrid controller and the brake release command signal is transmitted from the pump controller through the inter-controller signal line.

Abstract: A steering device for a wheel loader includes a handle for steering, a lever for steering, a steering cylinder, a steering valve that controls a direction of operating fluid to the steering cylinder, a pump that supplies operating fluid to the steering cylinder via the steering valve, and a return oil passage connected to a tank. The steering device further includes a handle control valve that controls the supply direction of the operating fluid according the handle, a lever electromagnetic control valve that controls the supply direction of operating fluid according to the lever, and a handle prioritization valve that shuts off a pilot hydraulic pressure supplied from the lever electromagnetic control valve to the steering valve according to a pressure produced by operating fluid flowing through the handle control valve when the handle is operated. The handle prioritization valve includes a throttle arranged in the return oil passage.

Abstract: A steering device for a wheel loader includes a handle for steering, a lever for steering, a steering cylinder, a steering valve that controls a direction of operating fluid to the steering cylinder, and a pump that supplies operating fluid to the steering cylinder via the steering valve. The steering device further includes a handle control valve that controls the supply direction of the operating fluid according the handle, a lever electromagnetic control valve that controls the supply direction of operating fluid according to the lever, and a handle prioritization valve that shuts off a pilot hydraulic pressure supplied from the lever electromagnetic control valve to the steering valve according to a pressure produced by operating fluid flowing through the handle control valve when the handle is operated. The handle prioritization valve includes a switching valve and a priority control valve switchable between a handle stage and a lever stage.

Abstract: A steering device for a wheel loader includes a handle for steering, a lever for steering, a steering cylinder, a steering valve that controls a direction of operating fluid to the steering cylinder, and a pump that supplies operating fluid to the steering cylinder via the steering valve. The steering device further includes a handle control valve that controls the supply direction of the operating fluid according the handle, a lever electromagnetic control valve that controls the supply direction of operating fluid according to the lever, and a handle prioritization valve that shuts off a pilot hydraulic pressure supplied from the lever electromagnetic control valve to the steering valve according to a pressure produced by operating fluid flowing through the handle control valve when the handle is operated. Communication between the lever electromagnetic control valve and the steering valve is allowed when only the lever electromagnetic control valve is operated.

Abstract: A steering device for a wheel loader includes a rotatable handle, a tiltable lever, a steering cylinder, a steering valve, a pump, a handle control valve, a lever control valve, and a handle prioritization valve. The steering valve controls a supply direction of operating fluid to the steering cylinder with pilot hydraulic pressure. The pump supplies operating fluid to the steering cylinder via the steering valve. The handle and lever control valves supply pilot hydraulic pressure to control the supply direction to the steering valve according to handle rotation and lever tilt, respectively. The handle prioritization valve shuts off the pilot hydraulic pressure supplied from the lever control valve to the steering valve according to a differential pressure or an absolute pressure in a hydraulic circuit produced due to operating fluid flowing through the handle control valve when the handle is operated.

Abstract: A steering device for a wheel loader includes a rotatable handle, a tiltable lever, a steering cylinder, a steering valve, a pump, a handle control valve, a lever control valve, and a handle prioritization valve. The steering valve controls a supply direction of operating fluid to the steering cylinder with pilot hydraulic pressure. The pump supplies operating fluid to the steering cylinder via the steering valve. The handle and lever control valves supply pilot hydraulic pressure to control the supply direction to the steering valve according to handle rotation and lever tilt, respectively. The handle prioritization valve shuts off the pilot hydraulic pressure supplied from the lever control valve to the steering valve according to a differential pressure or an absolute pressure in a hydraulic circuit produced due to operating fluid flowing through the handle control valve when the handle is operated.

Abstract: The disclosed rotating parking brake control device obviates the need for an operator to operate an emergency-stop switch. A hybrid controller, to which a brake is connected, outputs a drive control signal to a rotating electric motor to control drive of an upper rotating body and also controls the brake by generating a brake release command signal and outputting the brake release command signal to the brake. A pump controller also generates a brake release command signal, and the brake release command signal generated by the pump controller is transmitted to the hybrid controller through an inter-controller signal line. The brake release command signal is outputted to the brake only when the brake release command signal is generated by the hybrid controller and the brake release command signal is transmitted from the pump controller through the inter-controller signal line.

Abstract: A control method of an EGR system of an engine capable of effectively performing an EGR control at a time of rapid acceleration. For this purpose, an intake air flow rate of the engine is obtained, and from a target EGR valve opening degree and a difference in pressure in front of and behind the EGR valve, a virtual EGR gas flow rate is arithmetically operated. A virtual EGR rate is obtained from the intake air flow rate, the fuel flow rate and the virtual EGR gas flow rate, and a difference from or a ratio to a target EGR rate obtained from the engine speed and the fuel flow rate is obtained. A command EGR valve opening degree is obtained from an EGR valve opening degree correction coefficient obtained from the difference or the ratio, and the target EGR valve opening degree, whereby the EGR vale is driven.

Abstract: In a fuel injection apparatus 1, a fuel injection rate from which is controlled by a fuel pressure, a branch pipe 11 comprising a tubular member with the tip end closed is provided between a second pressure control valve 9 and a second pressure sensor 10. The branch pipe 11 extends in a direction along a flow direction of the fuel just before the branch pipe 11, and has a capacity not less than one fifth of that of a fuel flow path 22 between the second pressure control valve 9 and a fuel chamber 17. When a pressure difference in the pressure control valve 9 becomes larger and vibration of the fuel pressure is generated, the branch pipe 11 absorbs and reduces the vibration. As the vibration of the fuel pressure is reduced, a stable fuel injection rate is realized.

Abstract: A control method of an EGR system of an engine capable of effectively performing an EGR control at a time of rapid acceleration. For this purpose, an intake air flow rate of the engine is obtained, and from a target EGR valve opening degree and a difference in pressure in front of and behind the EGR valve, a virtual EGR gas flow rate is arithmetically operated. A virtual EGR rate is obtained from the intake air flow rate, the fuel flow rate and the virtual EGR gas flow rate, and a difference from or a ratio to a target EGR rate obtained from the engine speed and the fuel flow rate is obtained. A command EGR valve opening degree is obtained from an EGR valve opening degree correction coefficient obtained from the difference or the ratio, and the target EGR valve opening degree, whereby the EGR vale is driven.

Abstract: In a fuel injection apparatus 1, a fuel injection rate from which is controlled by a fuel pressure, a branch pipe 11 comprising a tubular member with the tip end closed is provided between a second pressure control valve 9 and a second pressure sensor 10. The branch pipe 11 extends in a direction along a flow direction of the fuel just before the branch pipe 11, and has a capacity not less than one fifth of that of a fuel flow path 22 between the second pressure control valve 9 and a fuel chamber 17. When a pressure difference in the pressure control valve 9 becomes larger and vibration of the fuel pressure is generated, the branch pipe 11 absorbs and reduces the vibration. As the vibration of the fuel pressure is reduced, a stable fuel injection rate is realized.

Abstract: This invention aims to improve the operability in a hydraulic drive machine. According to a load Pp on work machine actuators 3 and 4, a differential pressure of a discharge pressure Pp of a hydraulic pump and a load pressure PLS is varied. Further, the differential pressure is varied so that the differential pressure between the discharge pressure Pp of the hydraulic pump 2 and the load pressure PLS decreases as the load Pp on the work machine actuators 3 and 4 increases and a rotational speed .epsilon.E of an engine decreases. Furthermore, the rotational speed .epsilon.E of the engine 1, discharge pressure Pp of the hydraulic pump 2, the operation amounts S1 and S2 of the various operation levers are detected, respectively, the absorbing torque of the hydraulic pump 2 is set based on the detected rotational speed .epsilon.E and a target rotational speed .epsilon.

Abstract: A data collection system for a driving machine for collecting data obtained at a plurality of controllers disposed within the driving machine, in which one of the plurality of controllers is used as a master controller to perform sequential polling operation over the other controllers including an external controller through a communication line. The other controller subjected to the polling transmits data obtained at its own controller to the controllers other than its own controller. The master controller continues its polling operation so long as the master controller fails to receive a response to the polling from the external controller. The master controller, when receiving the response to the polling from the external controller, judges that the external controller was connected to a connector for connection with the external controller and stops its polling operation.

Abstract: An apparatus for controlling a power shovel or like construction machine which assures that various control modes for performing certain operations can reliably be selected by merely activating a switch corresponding to the operation to be performed. When a certain operation is selected, a CPU and an operation panel inputs a signal indicative of the selected operation into a pump controller. The pump controller outputs a signal indicative of the magnitude of the target engine revolution number and a magnitude of composite suction torque of the pumps adapted to the selected operation to an electric governor controller and a TVC valve. In response to this signal, the governor controller controls a governor and swash plates of the pumps such that the target engine revolution number is reached and the output torque from the engine matches the composite suction torque of the pumps.