METHOD OF AUTOMATICALLY CHANGING SPEED OF DUMP TRUCK FOR USE AS CONSTRUCTION VEHICLE

摘要

PURPOSE:To reduce fuel consumption rate and power loss by employing automatic speed change suitable for a damp truck under normal driving, and enabling driving with high speed stage in driving with constant speed under partial output state of engine. CONSTITUTION:Second control circuit 62 judges whether speed can be changed to a higher stage than current speed based on an output state of engine and torque fed from second control circuit 54 in an engine controller 50 and a speed stage signal fed from first control circuit 61. If possible, signals are fed to 1st-7th speed change valves 31-37 and a lockup changeover valve 41 so as to change the speed to higher stage, while simultaneously a fuel injection quan tity control signal for performing equi-power control is outputted to a first control circuit 53 in an engine controller 50.