초록 ▼

The linear actuator has a motor housing ( 1 ) of tubular stainless steel with an end cap ( 2 ), a motor ( 4 ) and epicyclic gearbox ( 6 ). The actuator has a telescopic arm ( 11 ), having an outer tube ( 12 ) and an inner tube ( 13 ) of stainless steel. The outer tube is removably attached to the mo

The linear actuator has a motor housing ( 1 ) of tubular stainless steel with an end cap ( 2 ), a motor ( 4 ) and epicyclic gearbox ( 6 ). The actuator has a telescopic arm ( 11 ), having an outer tube ( 12 ) and an inner tube ( 13 ) of stainless steel. The outer tube is removably attached to the motor housing. An extension screw ( 16 ) is provided in the arm with a driven end ( 16 ) journalled at the motor housing end ( 17 ) of the outer tube. At its inner end, the inner tube has threaded into it a plastics material nut ( 18 ), in which the screw engages. The end of the screw ( 16 ) has a clevis ( 23 ), open ( 24 ) axially away from the screw. The output shaft ( 7 ) from the gear box has a cross pin ( 31 ) through it. On each side of the shaft, the pin carries a respective roller ( 32 ), sized to fit in the clevis ( 23 ). The clevis and rollers form a dog clutch for transfer of drive from the gearbox to the extension screw. The telescopic arm is readily dismounted from the motor housing by unscrewing the disc ( 21 ) and axially withdrawing the clevis from the rollers.

대표청구항 ▼

1. A linear actuator comprising:a motor housing having one end fitting, a motor housed in the motor housing,a reduction gearbox housed in the h sing, the motor being connected to an input of the gearbox,a telescope arm, having an outer tube attachable to the motor housing, an inner tube having anoth

1. A linear actuator comprising:a motor housing having one end fitting, a motor housed in the motor housing,a reduction gearbox housed in the h sing, the motor being connected to an input of the gearbox,a telescope arm, having an outer tube attachable to the motor housing, an inner tube having another end fitting, an extension screw contained within the telescopic arm and the motor housing and having a driven end journalled at the motor housing end of the outer tube and engaging a nut fast at the proximal end of the inner tube, rotation of the screw causing the inner tube to extend or retract with respect to the outer tube,characterised in that the linear actuator further comprises:an engageable connection of an output of the reduction gearbox and the driven end of the extension screw for transmitting drive from the gearbox to the extension screw for extension and retraction of the inner tube. 2. A linear actuator as claimed in claim 1, wherein the engageable connection is an axially engageable dog clutch. 3. A linear actuator as claimed in claim 2, wherein dog clutch comprises a clevis and a spigot with a transverse pin engageable in the clevis, the clevis being connected to one of the extension screw and the gearbox output and the spigot and pin being connected to the other. 4. A linear actuator as claimed in claim 3, wherein the transverse pin has a pair of rollers arranged on it, the rollers being on respective opposite sides of spigot. 5. A linear actuator as claimed in claim 1, wherein the detachable connection of the telescopic arm and the motor housing is a screw connection. 6. A linear actuator as claimed in claim 5, wherein the motor housing is tubular and the outer rube has a disc attached at its motor housing end, the screw connection comprising complementary threads cut in the disc and the motor housing. 7. A linear actuator as claimed in claim 6, including a bearing for journalling the extension screw in the telescopic arm the outer tube being threadedly attached to the disc and the bearing being captivated by the threaded attachment, the latter preferably being sealed by thread sealant. 8. A linear actuator as claimed in claim 5, wherein the screw connection incorporates an O-ring seal for sealing the telescopic arm to the motor housing. 9. A linear actuator as claimed in claim 1, wherein the motor is resiliently mounted in the motor housing. 10. A linear actuator as claimed in claim 1, wherein the output of the gearbox is provided with a rotation counter. 11. A linear actuator as claimed in claim 1, including a seal between the inner tube and the outer tube, the seal leaving the tubes being free to rotate relatively about a common axis, the end fittings being adapted to restrain relative rotation for extension and retraction of the telescopic arm. 12. A linear actuator as claimed in claim 1, wherein the nut at the end of the inner tube and having the extension screw engaged therein is of generally weaker material than the other components, whereby it forms a weak link in the event of overloading the actuator.