Abstract: A hybrid work machine is configured with an engine 41, a hydraulic pump 51, a hydraulic actuator, a generator motor 61 coupled to the engine 41, an electric storage device 62 that transmits and receives electric power to and from the generator motor 61, an engine controller 42 that controls the engine 41 based on a target engine revolution speed, a power controller 63 that controls action of the generator motor 61, a controller 72 that controls the engine controller 42 and the power controller 63, and a target engine revolution speed change instructing device that give instructions on a change in the target engine revolution speed. The controller 72 controls the engine controller 42 and the power controller 63 to act the generator motor 61 as a generator until an actual revolution speed of the engine 41 is reduced to a revolution speed corresponding to a target engine revolution speed after change if the target engine revolution speed has been changed to be lower while the engine 41 is in an unloaded state.

Abstract: A hybrid work machine is configured with an engine 41, a hydraulic pump 51, a hydraulic actuator, a generator motor 61 coupled to the engine 41, an electric storage device 62 that transmits and receives electric power to and from the generator motor 61, an engine controller 42 that controls the engine 41 based on a target engine revolution speed, a power controller 63 that controls action of the generator motor 61, a controller 72 that controls the engine controller 42 and the power controller 63, and a target engine revolution speed change instructing device that give instructions on a change in the target engine revolution speed. The controller 72 controls the engine controller 42 and the power controller 63 to act the generator motor 61 as a generator until an actual revolution speed of the engine 41 is reduced to a revolution speed corresponding to a target engine revolution speed after change if the target engine revolution speed has been changed to be lower while the engine 41 is in an unloaded state.

Abstract: A system enables notification of a time for drainage of water from a water separator without adding a new element into the water separator. A hydraulic excavator has a feed line feeding fuel from a fuel tank to an engine, a water separator at a part of the feed line to separate fuel flowing through the feed line and water contained in the flowing fuel from each other, a water level detector detecting a level of separated water, and a notification device to provide notification of when the water level detected reaches a predetermined height. An operation determination device determines whether or not the hydraulic excavator is in operation, and a notification control device disables a notifying function of the notification device when it is determined that the hydraulic excavator is in operation and enables the notifying function when the hydraulic excavator is determined to be out of operation.

Abstract: An object is to reduce a load acting on an engine upon starting up the engine such that the engine can be quickly started up to reliably feed pressure oil from a hydraulic pump to an accumulator.

Abstract: An object is to reduce a load acting on an engine upon starting up the engine such that the engine can be quickly started up to reliably feed pressure oil from a hydraulic pump to an accumulator.

Abstract: An object is to provide a working machine that enables to appropriately become aware of a time for drainage of water from a water separator without adding a new element into the water separator.

Abstract: An exhaust gas treatment apparatus for a working machine is provided to reliably prevent a specific process that raises the exhaust temperature of an exhaust gas treatment section from being carried out during switching operation of a directional control valve.

Abstract: There are provided: a pedal operation amount detection unit 12 that detects an operation amount s of the accelerator pedal 11; a speed ratio detection unit 14, 15 that detects a speed ratio e of an input shaft and an output shaft of the torque converter 2; a load pressure detection unit 16 that detects a load pressure P of the hydraulic pump 6; a speed stage detection unit 18 that detects a low speed stage of a transmission 3 capable of varying a speed stage between a low speed stage and a high speed stage; and a speed limiting unit 10 that limits a maximum speed of the engine 1 to a lower speed upon satisfaction of following speed limitation conditions: at least a pedal operation amount s is equal to or greater than a predetermined value s1, a speed ratio e is equal to or less than a predetermined value ea, a load pressure P is equal to or greater than a predetermined value Pa, and the low speed stage of the transmission has been detected.

Abstract: An exhaust gas treatment apparatus for a working machine is provided to reliably prevent a specific process that raises the exhaust temperature of an exhaust gas treatment section from being carried out during switching operation of a directional control valve.

Abstract: To provide a steering system for a construction vehicle, which is suited not only for traveling on general roadways but also for work at construction sites and can perform high-reliability steering control. A steering system for a construction vehicle is provided with a directional control valve 5 for controlling a flow of pressure oil to body-articulating hydraulic cylinders 2 that perform steering and also with a steering-wheel-operated signal generation means 6 for outputting by operation of a steering wheel 7a a pilot signal to the directional control valve 5 for switching the valve 5.

Abstract: There are provided: a pedal operation amount detection unit 12 that detects an operation amount s of the accelerator pedal 11; a speed ratio detection unit 14, 15 that detects a speed ratio e of an input shaft and an output shaft of the torque converter 2; a load pressure detection unit 16 that detects a load pressure P of the hydraulic pump 6; a speed stage detection unit 18 that detects a low speed stage of a transmission 3 capable of varying a speed stage between a low speed stage and a high speed stage; and a speed limiting unit 10 that limits a maximum speed of the engine 1 to a lower speed upon satisfaction of following speed limitation conditions: at least a pedal operation amount s is equal to or greater than a predetermined value s1, a speed ratio e is equal to or less than a predetermined value ea, a load pressure P is equal to or greater than a predetermined value Pa, and the low speed stage of the transmission has been detected.

Abstract: [Problem] To provide a steering system for a construction vehicle, which is suited not only for traveling on general roadways but also for work at construction sites and can perform high-reliability steering control. [Solution] A steering system for a construction vehicle is provided with a directional control valve 5 for controlling a flow of pressure oil to body-articulating hydraulic cylinders 2 that perform steering and also with a steering-wheel-operated signal generation means 6 for outputting by operation of a steering wheel 7a a pilot signal to the directional control valve 5 for switching the valve 5.

Abstract: A traveling working vehicle maintains fuel economy while ensuring a sufficient work rate in heavy-load work. A torque control regulator 26 controls the absorption torque of a hydraulic pump 22 to ensure that it does not exceed a preset maximum absorption torque, and an accelerator pedal 12 commands a target revolution speed of an engine 1. Revolution speed deviation computing sections 52 and 62, a modification torque computing section 53, a modification revolution speed computing section 63, speed ratio computing sections 54 and 64, traveling state determining sections 55 and 65, and working state determining sections 56 and 66 determine an operating state of the traveling working vehicle. Both the pump base torque of the hydraulic pump 22 and the target revolution speed of the engine 1 are modified depending on the determination result of the state determining sections.

Abstract: The invention provides a control system for a working vehicle, which can realize higher work performance and better fuel economy in a compatible way. A controller 10 includes table 10a, 10b and tables 10e, 10f for deciding maximum pump absorption torques and engine output torques based on an engine revolution speed, and selectors 10c, 10g for switching over the decided maximum pump absorption torques and engine output torques depending on a work performance mode or a fuel economy mode is selected. A pump absorption torque characteristic for the fuel economy mode is set so as to provide a relative small maximum pump absorption torques TB in a high revolution range, and an engine output characteristic for the fuel economy mode is set so as to provide a relatively small engine output torque in the high revolution range.

Abstract: [Object] To materialize a reduction in pump loss, the assurance of sufficient working device speeds and the priority assurance of an adequate steering capacity with simpler construction and at lower cost than a load sensing system.

Abstract: A modification torque ?T and a torque converter speed ratio e is computed from input and output revolution speeds of a torque converter 31. A first determination coefficient ? corresponding to the speed ratio e, and a second determination coefficient ? corresponding to a pump pressure are computed. A selector 87 selects the smaller one of these coefficients as a determination coefficient ?, and the modification torque ?T is multiplied by ? to provide a modification torque ?TA. An adder 89 adds the modification torque ?TA (negative value) to a pump base torque TR to provide a modified pump base torque TRA, whereby a maximum pump absorption torque TRA is controlled so as to become TRA. The maximum pump torque reducing control can then be performed while accurately confirming a work situation during the combined operation of travel and a working actuator.

Abstract: A traveling working vehicle maintains fuel economy while ensuring a sufficient work rate in heavy-load work A torque control regulator 26 controls the absorption torque of a hydraulic pump 22 to ensure that it does not exceed a preset maximum absorption torque, and an accelerator pedal 12 commands a target revolution speed of an engine 1. Revolution speed deviation computing sections 52 and 62, a modification torque computing section 53, a modification revolution speed computing section 63, speed ratio computing sections 54 and 64, traveling state determining sections 55 and 65, and working state determining sections 56 and 66 determine an operating state of the traveling working vehicle. Both the pump base torque of the hydraulic pump 22 and the target revolution speed of the engine 1 are modified depending on the determination result of the state determining sections.

Abstract: A modification torque computing unit 83 computes a modification torque ?T and a torque converter speed ratio e is computed from input and output revolution speeds of a torque converter 31. A first determination coefficient ? corresponding to the speed ratio e, and a second determination coefficient ? corresponding to a pump pressure are computed. A selector 87 selects the smaller one of these coefficients as a determination coefficient ?, and the modification torque ?T is multiplied by ? to provide a modification torque ?TA. An adder 89 adds the modification torque ?TA (negative value) to a pump base torque TR to provide a modified pump base torque TRA, whereby a maximum pump absorption torque TRA is controlled so as to become TRA. The maximum pump torque reducing control can then be performed while accurately confirming a work situation during the combined operation of travel and a working actuator.

Abstract: The invention provides a control system for a working vehicle, which can realize higher work performance and better fuel economy in a compatible way. A controller 10 includes tables 10a, 10b and tables 10e, 10f for deciding maximum pump absorption torques and engine output torques based on an engine revolution speed, and selectors 10c, 10g for switching over the decided maximum pump absorption torques and engine output torques depending on a work performance mode or a fuel economy mode is selected. A pump absorption torque characteristic for the fuel economy mode is set so as to provide a relatively small maximum pump absorption torques TB in a high revolution range, and an engine output characteristic for the fuel economy mode is set so as to provide a relatively small engine output torque in the high revolution range.