초록 ▼

A linear actuator having an output shaft having a pair of driven wheels mounted thereon. One of the driven wheels is rotatably mounted in a fixed plane and has a drive nut for an associated thread on the output shaft. The other drive wheel is rotatably fixed to the output shaft. An input shaft is in

A linear actuator having an output shaft having a pair of driven wheels mounted thereon. One of the driven wheels is rotatably mounted in a fixed plane and has a drive nut for an associated thread on the output shaft. The other drive wheel is rotatably fixed to the output shaft. An input shaft is in side-by-side relationship with the output shaft and adapted to be rotated by a suitable power source. The input shaft provides a drive wheel for each of the driven wheels, with the ratio between each drive and driven wheel set being chosen to rotate the driven wheels at different speeds in the same rotational direction and thereby produce a controlled axial movement of the output shaft in a direction depending upon the relative rotation of the driven wheels. The other driven wheel and the drive wheel of its set are in the form of meshing helical gear wheels. A fail-safe arrangement is provided and has a clutch between the drive wheels of the input shaft, a back-drive for the output shaft, and biasing means for effecting a back-drive. The arrangement is such that the meshing helical gears impart an axial force to engage the clutch only while power is supplied, and the biasing means are operative to back-drive the output shaft to a fail-safe position when the power is terminated.

대표청구항 ▼

[ We claim:] [1.] A linear actuator comprising an output shaft having a pair of driven wheels mounted thereon, one of said pair of driven wheels being rotatably mounted in a fixed plane and having a drive nut for an associated thread on said output shaft, the other of said pair of driven wheels bein

[ We claim:] [1.] A linear actuator comprising an output shaft having a pair of driven wheels mounted thereon, one of said pair of driven wheels being rotatably mounted in a fixed plane and having a drive nut for an associated thread on said output shaft, the other of said pair of driven wheels being rotatably fixed to said output shaft, and an input shaft in side-by-side relationship with said output shaft, said input shaft being adapted to be rotated by a suitable power source, said input shaft providing a drive wheel for each of said driven wheels, 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 a controlled axial movement of said output shaft in a direction depending upon the relative rotation of said driven wheels, wherein said other driven wheel and the drive wheel of its set are in the form of meshing helical gear wheels, and wherein a fail-safe arrangement is provided comprising a clutch between the drive wheels of the input shaft, a back-drive for said output shaft, and biasing means for effecting a back-drive, the arrangement being such that the meshing helical gears impart an axial force to engage the clutch only while power is supplied and the biasing means are operative to back-drive the output shaft to a fail-safe position when the power is terminated.