| 摘要 |
A hatch 2 comprises two doors 6,7 hinged to opposite sides of an aperture. A first door 6, the first to be opened and the second to be closed, has a lip 8 which overlaps the top of the second door 7. Fluid filled actuated piston and cylinder actuators 12, 13, are provided for opening and closing the doors. Each door has at least one actuator for opening the door and at least one actuator for closing the door, each opening actuator is connected to a common pressure supply and each closing actuator is connector to a common pressure source. The opening actuator of the first door provides a greater opening force or torque than the actuator of the second door and the first door opens first ahead of the second door. The closing actuator of the second door provides a greater closing force or torque than the actuator of the first door and the second door begins to close before the first door. The increased opening and closing forces/torques of the respective actuators may be due to a mechanical advantage or may be due to an increased piston area of the actuator. In one arrangement (fig. 4) actuators 11,12 are connected to the first door 6 and actuators 13,14 are connected to the second door 7. Pneumatic ducts 18,19 for opening and closing pressurised air are provided from connections 20,21 and associated vents 22,23. The ducts are connected to the actuators in the manner shown in Figure 4. Opening pressure supply duct 18 is connected to two actuators 11, 12, on the first door and a single actuator 13 on the second door. Closing pressure supply 19 is connected to a single actuator 12 on the first door and two actuators 13, 14 on the second door. |
