1.电磁换向阀electromagnetic directional valve（如果是强调用线圈做磁场，则为solenoid directional valve） 2. 叠加式液控单向阀stacked pilot-controlled check valve 3. 叠加式溢流阀stacked discharge valve
4. 叠加式单向节流阀stacked one-way throttle valve 5. 分流阀flow divider (valve)