OIL-HYDRAULIC CONTROL CIRCUIT DEVICE OF STEPLESS SPEED CHANGER WITH BELT

摘要

PURPOSE:To prolong the life of a belt by using a common oil pressure source for the belt pinch force controlling hydraulic part and the F/N/R (forward/ neutral/rear) changeover controlling hydraulic part, and connecting the two oil hydraulic parts together with a proportional pressure valve or a check valve interposed. CONSTITUTION:When a selector valve 12 is operated in N F (neutral rear), the pressure oil from a pump 3 flows to a F-side clutch cylinder 13 via a quick return valve 10, inching valve 11, and selector valve 12. At this time, the valve 10 is actuated by the oil flow to lower the oil pressure set by the valve 5, and in this condition, the supply pressure P2 is free from influence of variation of P1 owing to operation of the check valve 4. When the F-side clutch cylinder 13 is filled with oil, the oil pressure set by the valve 5 is boosted to become normal oil pressure, and the supply pressure P2 in the belt pinch force controlling hydraulic part A will become specified oil pressure in normal period to ensure that a belt 1 is pinched and retained with good stability. Operation in N R (neutral rear) should provide operation in the same manner.