An engine of a working
truck in which
adverse effect of
oil temperature rise is avoided, by lessening the load applied to an accelerator when the working
truck is traveling while elevating the boom and approaching a place for discharging the load in the bucket during dump approach and, reducing heat generated through operation of a
brake, and deterioration in work efficiency of the working
truck is avoided by preventing the elevating speed of a boom from decreasing. A
hydraulic pump controller and a method for controlling the
hydraulic pump are also provided. On condition that a
throttle amount sensor detects the operating amount of an acceleration pedal reaching a prescribed threshold value (operation amount 70%), a
brake pressure sensor detects operation (
brake on) of a brake, and a vehicle speed sensor detects the body speed reaching a prescribed threshold value, a transmission controller delivers a
throttle correction command
signal for reducing the target engine speed to a
governor through an engine controller, and delivers a boom elevating time
cam plate inclination angle alteration command for sustaining delivery flow rate of the
hydraulic pump by supplementing reduction in delivery flow rate of the hydraulic pump by a
throttle correction command to a pump control valve through a working
machine controller.