| 摘要 |
An apparatus (10) for turning the steerable wheels (17) of a vehicle in response to the turning of the steering wheel (12). The apparatus (10) includes a drive mechanism (16), a first motor (24), a second motor (74), a sensor (78) for sensing that the first motor (24) is inoperative, and a torque sensor (80). In response to the turning of the steering wheel (12), the drive mechanism (16), is actuated, resulting in a turning the steerable wheels (17). The first motor (24), for inputting motion to the drive mechanism (16), is hydraulically powered. The second motor (74), for inputting motion to the drive mechanism (16), is electrically powered. The sensor (78) for sensing that the first motor (24) is inoperative produces an enabling signal and communicates the enabling signal to the second motor (74) to enable the operation of the second motor (74). The torque sensor (80) responds to the turning of the steering wheel (12) and controls the second motor (74) when the second motor (74) is enabled.
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