| 摘要 |
A fluid pressure operated actuator assembly comprising a tubular body (110) having a wall, with an interior surface and an exterior surface and enclosing a main passage (112) which extends generally parallel to a longitudinal axis of the tubular body, an actuator (118) located in and movable along the main passage, a first direction chamber (138a) formed between the wall of the tubular body and the actuator, and at least one second direction chamber (138b, c) formed between the tubular body and the actuator, wherein the assembly is configured such that when the pressure of fluid in the first direction chamber exceeds the pressure of fluid in the or each second direction chamber by a predetermined amount, the pressure of fluid in the first direction chamber exerts a force on the actuator which acts to push the actuator in a first direction relative to the tubular body, and when the pressure of fluid in the or at least one of the second direction chamber(s) exceeds the pressure of fluid in the first direction chamber by a predetermined amount, the pressure of fluid in the second direction chamber(s) exerts a force on the actuator which acts to push the actuator in a second direction relative to the tubular body, characterised in that the exterior surface of the tubular body is provided with a first port (140a) which communicates with a passage (139a) extending through the wall of the tubular body from the first port to the first direction chamber, a second port (140b) which communicates with a passage (139b) extending through the wall of the tubular body from the second port to the or one of the second direction chamber(s), and a third port (140c) which communicates with a passage (139c) extending through the wall of the tubular body from the third port to the or another one of the second direction chamber(s), the first port lying on a first plane, the second port lying on a second plane and the third port lying on a third plane, the first plane, second plane and third plane being generally parallel to one another and the first plane lying between the second plane and the third plane. |
