| 摘要 |
<p>The linear actuator comprises an output shaft (4) having a pair of driven wheels (6, 8), one (8) being rotatable thereon in a fixed plane and having a drive nut (9) for an associated thread (11) on said output shaft and the other (6) being rotatably fixed (6A) to said output shaft, an input shaft (2) alongside the output shaft which is rotated by a suitable power source (3) and a drive wheel (5, 7) for each driven wheel rotatably fixed on said input shaft, the ratio between each drive and driven wheel set being chosen to rotate the driven wheels at different speeds in the same rotational direction to produce axial movement of said output shaft in a direction depending upon relative rotation of the driven wheels. In accordance with the invention the fixed driven wheel (6) and drive wheel (5) are meshing helical gear wheels, and a fail-safe arrangement is provided comprising a clutch (27, 29) between the drive wheels (5, 7) of the input shaft, a back-drive (9, 11) for said output shaft, and biasing means (22) for effecting a back-drive. In operation the meshing helical gears impart an axial force to engage the clutch only while power is supplied, the biasing means being operative to back-drive the output shaft to a fail-safe position when the power is terminated. The actuator can be readily modified to be operated by a remote operating vehicle (ROV) in undersea applications.</p> |
