| 摘要 |
<p>The hydraulic control apparatus includes an actuator (18) having an annular body (32) providing an annular piston chamber (41) therein and an annular piston (44) slidably reciprocable on the body, the actuator being pre-filled with hydraulic fluid and pre-tested prior to being installed on a structure. An annular elastomeric seal (43) is axially reciprocable within the piston chamber to move the piston the construction of the piston being such that a rear end thereof reaches into the piston chamber and abuts against the seal during functioning of the actuator. A movement restraining device (54) is provided for insertion on the body to take the place of the piston, the movement restraining device being constructed so that it is slidable on the body and so that a rear end thereof reaches into the piston chamber and abuts against the seal. The movement restraining device is forcefully held on the body, e.g. frictionally, to hold the seal against axial movement while the actuator is filled with hydraulic fluid. It is removed during installation of the actuator, e.g. in a vehicle, and replaced by the piston.</p> |
