4-7 如题图4-7所示,溢流阀调定压力ps1=5 MPa,减压阀的调定压力ps2=1.5 MPa,ps3=3.5 MPa,活塞运动时,负载FL=2000N,活塞面积A=20×10-4 m2,减压阀全开时的压力损失及管路损失忽略不计。求: (1)活塞运动时,A、B、C各点的压力是PA= MPa,PB= MPa,PC= MPa; 活塞到达终点时,A、B、C各点的压力是PA= MPa,PB= MPa,PC= MPa; (2)当负载FL=4000 N时,活塞运动时,A、B、C各点的压力是PA= MPa,PB= MPa,PC= MPa; 活塞到达终点时,A、B、C各点的压力是PA= MPa,PB= MPa,PC= MPa。 图 4.7