Patent ID: 8082082

Claim:
An engine load control device for a working vehicle in which output of an engine is transmitted to drive wheels and to a plurality of hydraulic actuators including a working equipment hydraulic actuator via a plurality of variable capacity hydraulic pumps with an engine speed being controlled by a speed instruction device, the engine load control device comprising: an engine speed detection unit configured and arranged to detect the engine speed; an instruction contents detection unit configured and arranged to detect contents of instructions of the speed instruction device; a hydraulic pump load detection unit configured and arranged to detect load of at least one load detection hydraulic pump of among the variable capacity hydraulic pumps; and an absorption torque control unit configured to control absorption torque of at least one control hydraulic pump among the variable capacity hydraulic pumps other than the load detection hydraulic pump based on detection results of the engine speed detection unit, the instruction contents detection unit, and the hydraulic pump load detection unit, the absorption torque control section including a first fall rate determining section configured to determine a first fall rate for lowering the absorption torque of the control hydraulic pump so that the engine speed does not become equal to or less than a second engine speed that is equal to or less than a prescribed low idle speed set for preventing the engine from stopping, a second fall rate determining section configured to determine a second fall rate for lowering the absorption torque of the control hydraulic pump according to the engine speed, a third fall rate determining section configured to determine a third fall rate for lowering the absorption torque of the control hydraulic pump according to the contents of the instructions for the engine speed, a fourth fall rate determining section configured to determine a fourth fall rate for lowering the absorption torque of the control hydraulic pump according to the load of the load detection hydraulic pump, a minimum fall rate selecting section configured to select a minimum fall rate among the second, third and fourth fall rates, a maximum fall rate selecting section configured to select a largest fall rate between the first fall rate and the minimum fall rate, and an absorption torque lowering section configured to lower the absorption torque of the control hydraulic pump according to the fall rate selected by the maximum fall rate selecting section.