如图所示的液压系统,两液压缸有效面积为 A 1 =A 2 =100cm 2 ,缸 I 的负载 F L =35000N ,缸II运动时负载为零,不计摩擦阻力、惯性力和管路损失。溢流阀、顺序阀和减压阀的调整压力分别为 4MPa , 3MPa 和 2MPa 。求下列三种情况下 A 、 B 和 C 点的压力。 l) 液压泵启动后,两换向阀处于中位时; 2)1YA 通电,液压缸 I 活塞移动活塞运动到终点时; 3)1YA 断电, 2YA 通电,液压缸 II 活塞运动活塞杆碰到固定挡铁时。
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【简答题】阅读理解。 Sam and his sister Mary are students. They have breakfast at home. After breakfast, they take a bus to school. Their morning classes start at 8:30. They have four classes in the morning. In the ...