| 摘要 |
PROBLEM TO BE SOLVED: To reduce shift shock during high speed travel and improve work efficiency during work by inputting rotation detected value before the input of a torque converter and after a transmission output shaft to a transmission controller, and performing slow-quick control of a boosting curve of oil pressure of a changeover clutch according to both value at the time of downshift from second gear speed to first gear speed. SOLUTION: During work of scooping sediment into a bucket after downshift from forward second gear speed to first gear speed in a wheel loader, a speed area is in a decelerating area until scooping, and an engine speed signal is low, while a vehicle speed signal is high. At this time, a control current is outputted from a transmission controller 10 to a proportional solenoid 15a, and slow shift is performed by a solenoid proportional pressure control valve 15 to prevent shift shock. When the wheel loader is put in sediment scooping work, traveling resistance increases, and even though the engine speed signal is high, the vehicle speed signal is lowered by sliding action of a torque converter 2. At this time, sudden shift is performed, and work efficiency can beimpred by shift without time lag and toque break. |
