| 摘要 |
<p>The cylinder (10) of the actuator comprises, in its head part (12), a fixed annular dividing wall (28) extending towards the piston (14). This dividing wall (28) defines in its interior a head chamber (20) and, around its exterior, a blind annular chamber forming a power chamber (30). The piston (14) comprises a projection (34) that slides inside the power chamber (30). The dividing wall (28) comprises at least one transverse passage (36) for communication between the head chamber (20) and the power chamber (30). This passage (36) is closed by the annular projection (34) in all positions of the piston (14) between the rest end-of-stroke position and a mid-stroke position in order to prevent the hydraulic pressure from being applied from the head chamber (20) to the power chamber (30). The passage (36) is opened by the annular projection (34) in all positions of the piston (14) between the abovementioned mid-stroke position and the working end-of-stroke position. The abovementioned power chamber (30) is preferably a low-power chamber. Between the annular projection (34) and the rod (16), the piston (14) comprises a cylindrical collar (38) whose diameter is greater than the diameter of the annular projection (34). The cylinder (10) comprises a cylindrical cavity in which the collar slides and this cavity forms a high-power chamber (40) which can selectively receive the pressurized hydraulic fluid on the side of the collar (38) nearest the head part (12) of the cylinder (10).</p> |
