| 摘要 |
<p>A farm tractor includes differentials interposed in the front and rear axles of an agricultural vehicle. The differentials include hydraulically-operated locks each controlled by a solenoid-operated valve. The solenoid valves are controlled by a control circuit which includes a latching relay, a normally open manual switch operable only to close the relay and lock the differential and a pair of series-connected, normally closed switches which are operable only to unlock the differential in response to vehicle steering or braking operation.</p> |
