| 摘要 |
A piston-in-cylinder type pneumatic actuator is provided with an automatic cushioning facility to prevent the piston from returning to its fully retracted position at velocities exceeding a predetermined maximum velocity. Integrally-housed in the actuator is a velocity transducer arranged to sense the pressure in a cylinder working volume, which pressure is related to the piston velocity and is used to control the operation of an exhaust valve operable to vary the rate of flow of gas from the cylinder thereby to vary the rate of return of the piston.
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