Abstract: An engine lag down control system for construction machinery has a machinery body controller having first, second and third torque control units and a solenoid valve. The first torque control unit controls a torque control valve to a minimum pump torque corresponding to a target number of engine revolutions when a non-operated state of a control device has continued beyond a monitoring time. The second torque control unit controls the torque control valve such that the above-described minimum pump torque is held for a predetermined holding time subsequent to the operation of the control device from the non-operated state. The third torque control unit controls the torque control valve such that from a time point of a lapse of the predetermined holding time, the pump torque is gradually increased on a basis of a predetermined torque increment rate.

Abstract: A power source control circuit for a working machine includes an electric circuit connecting a key cylinder, controller and accessories. The electric circuit is provided with a first self-holding relay drivable directly by a relay drive signal outputted from the controller and second self-holding relays drivable in conjunction with the first relay. When a gate lock switch is switched to a lock position while an engine is running, the controller outputs an engine stop signal at a subsequent predetermined timing to stop the running of the engine, and also outputs the relay drive signal to drive the first relay and second relays such that a key-on power supply and an accessory power supply are each held in a cut-off state.

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: An engine lag down suppressing device of construction machinery, comprising a vehicle body controller (13) having a first torque control means and a second torque control means, and a third torque control means. The first torque control means controls a torque control valve (7) to the minimum pump torque (value: Min) according to a target engine rotational speed (Nr) when the operating device (5) in the non-operated state of an continues for a monitoring time (TX1) to suppress an engine lag down after a specified holing time to hold a torque to a low pump torque is passed when the operating device in the non-operated state is operated. The second torque control means controls the torque control valve (7) to hold the minimum pump torque for a specified holding time (Tx2) after the operating device (5) in the non-operated state is operated.

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.