SPEED CHANGE CONTROLLER OF WORKING VEHICLE

摘要

A speed change controller performing speed change not leading to engine stall in a working vehicle such as a wheel loader while sustaining a required tractive force and reducing fuel consumption. When a speed ("drive", "second speed") suitable for a work is selected by a speed change operator, a control means makes a modulation clutch engaged in response to the vehicle speed drop and makes a lock-up state where a lock-up clutch is engaged transit to a lock-up and modulation clutch slip state where the lock-up clutch is engaged and the modulation clutch is slipping. Subsequently, the control means performs clutch control for causing transition to both clutch slip state where the lock-up clutch and the modulation clutch are slipping in response to the vehicle speed drop, thence causing transition to a torque converter operating state where the modulation clutch is engaged and the lock-up clutch is disengaged.