| 摘要 |
In a pneumatic control circuit, five three-port, two-position, directional control valves, three of which have manual controls, and two shuttle valves are arranged for controlling a first pneumatic device and a second pneumatic device in an operating mode wherein the second pneumatic device cannot be readily enabled before the first pneumatic device is enabled. A first control valve having a manual control is arranged to control the first pneumatic device. A second control valve having a pilot valve is arranged to control the second pneumatic device. A pilot control valve having a manual control is arranged to connect the first control valve to the pilot valve of the second control valve via a shuttle valve. A holding control valve has a cam control, which is operated by the second pneumatic device, and has an outlet connected to the pilot valve of the second control valve. A shut-off control valve is arranged to control the first control valve via another shuttle valve and via a pilot valve of the first control valve.
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