| 摘要 |
A power steering system to prevent a sub-pump from being unnecessarily operative in a normal operating state, and to effect steering assist when an engine stops. When a main pump (142) is operative in a normal state, oil in an oil tank (141) is supplied to a pump switching valve (121) in a power steering unit via a main feed passage (16a), and a front-wheel power cylinder (123) and a rear-wheel power cylinder (13) effect steering assist for wheels by use of the oil from the main pump. In case an abnormal operation occurs on the main pump (141) or an oil pressure decreases due to an damage on the main feed passage (16a) and the like, a pressure detecting switch (143) detects it and sends an On-signal to a drive control unit (146). The drive control unit (146) that receives the On-signal then supplies a battery voltage to the sub-pump (145) to drive the sub-pump (145). The oil in the oil tank (144) is supplied to the pump switching valve (121) in the power steering unit (12) via a sub-feed passage (16c), and the power cylinder (13,123) is activated to effect steering assist for the wheels. <IMAGE>
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