| 摘要 |
<p>No shock develops when a driving state of a vehicle is switched from two-wheel driving to four-wheel driving. In a driving switching method of a two-wheel/four-wheel driving hydraulic travelling apparatus comprising a variable displacement hydraulic pump (1), a rear wheel driving hydraulic circuit including a variable capacity hydraulic motor (3) for driving rear wheels on receiving a driving pressure oil from a pump through a direction change-over valve (11R), a front wheel driving hydraulic circuit including a constant capacity hydraulic motor (2) for driving front wheels on receiving the driving pressure oil through a direction change-over valve (11F), a clutch (4) for intermittently connecting an output shaft of the constant capacity hydraulic motor with the front wheels, and a communication valve (12) capable of intermittent communication between the front wheel and rear wheel driving hydraulic circuits, the front wheel and rear wheel driving hydraulic circuits communicate with each other when a switching signal (S2) to four-wheel driving is transmitted from driving switching signal transmission means (7), a discharge flow rate (QP) from the pump and an excessive flow rate generated by changing the capacity of the variable capacity hydraulic motor are caused to flow into the front wheel driving hydraulic circuit, and when a flow rate (QF) at which the revolution of the constant capacity hydraulic motor synchronizes with that of the variable capacity hydraulic motor is reached, the clutch is engaged and the driving state is switched to the four-wheel driving state. <IMAGE></p> |
