A linear actuator (1) and the centrifugal safety device (50) thereof is disclosed. The safety device (50) includes an outer socket (51) having a stop portion (512) and a first accommodation portion (513), an inner socket (53) having a raised portion (531) and a second accommodation portion (532) and a centrifugal assembly (55) having a centrifugal block (551) and an elastic element (555). The inner socket (53) drives the centrifugal assembly (55) to rotate. If the centrifugal force of the centrifugal block (551) is smaller than the elasticity of the elastic element (555), then the centrifugal block (551) is limited in the second accommodation portion (532) by the elastic element (555), or else the centrifugal block (551) moves into the first accommodation portion (513) and clamped by the raised portion (531) and the stop portion (512).

According to an aspect of some embodiments of the present invention there is provided a piston mounted on and fixedly fastened to a ball screw nut, the nut threaded onto a ball screw. By mechanically rotating the piston and preventing the ball screw from rotating, the balls screw nut rotates, thereby raising or lowering the ball screw, thereby raising or lowering the piston, thereby raising or lowering a casing, for example a bollard, mounted on the piston. The casing may be raised or lowered by attaching a handle to the piston and rotating the handle.

A spring system that includes an adjustable spring system that is operated by a motor.

A linear actuator (1) and the centrifugal safety device (50) thereof is disclosed. The safety device (50) includes an outer socket (51) having a stop portion (512) and a first accommodation portion (513), an inner socket (53) having a raised portion (531) and a second accommodation portion (532) and a centrifugal assembly (55) having a centrifugal block (551) and an elastic element (555). The inner socket (53) drives the centrifugal assembly (55) to rotate. If the centrifugal force of the centrifugal block (551) is smaller than the elasticity of the elastic element (555), then the centrifugal block (551) is limited in the second accommodation portion (532) by the elastic element (555), or else the centrifugal block (551) moves into the first accommodation portion (513) and clamped by the raised portion (531) and the stop portion (512).

An opening and closing structure for an umbrella combining automatic and non-automatic modes including an electric mechanism, a cranking mechanism and a clutch structure is described herein. The electric mechanism includes a screw rod, a motor and a first transmission element. The motor is configured to drive rotation of the screw rod, and the first transmission element is mounted at the screw rod. The cranking mechanism includes a second transmission element and a cranking handle. The second transmission element is engaged with the first transmission element, and the second transmission element is connected with the cranking handle via the clutch structure. The invention overturns a conventional method of using an electric umbrella, and provides a manual lifting-and-lowering function under the premise of maintaining a electric lifting-and-lowering function, that is, in case of insufficient or no power supply, the umbrella can be opened and closed through the cranking handle.

According to an aspect of some embodiments of the present invention there is provided a piston mounted on and fixedly fastened to a ball screw nut, the nut threaded onto a ball screw. By mechanically rotating the piston and preventing the ball screw from rotating, the balls screw nut rotates, thereby raising or lowering the ball screw, thereby raising or lowering the piston, thereby raising or lowering a casing, for example a bollard, mounted on the piston. The casing may be raised or lowered by attaching a handle to the piston and rotating the handle.

An actuator is for use in petroleum exploitation and is configured for displacing a rod for engaging a well barrier device. The actuator has a housing for at least a portion of the rod; at least two roller screws rotatably arranged in the housing; rotational means connected to the roller screws via one gear systems for each roller screw for simultaneous rotation of the roller screws; and a roller nut engaging each roller screw. The roller screws and roller nuts are configured such that rotation of the roller screws result in displacement of the roller nuts relative to the roller screws. Each roller nut is coupled with one actuation element via spherical bearings, and each actuation element is configured for mechanical coupling to an end portion of the rod for displacing the rod in operational use.

Devices and methods for operating a linear actuator, optionally for use in controlling a choke valve as part of a managed pressure drilling operation. Such a device may include a motor, a transmission, a linear actuator and an override mechanism selectively engageable with the transmission to enable operation of the linear actuator independently of the motor.

An electromechanical actuator includes a first electric motor, a first motion conversion mechanism, a second motion conversion mechanism, and a rotation restriction mechanism for the second motion conversion mechanism. The first motion conversion mechanism includes a first member that is rotated by an output of the first electric motor and a second member that is fastened to the first member. The second motion conversion mechanism includes a third member that is movable integrally with the first member and a fourth member that is fastened to the third member. The rotation restriction mechanism is configured to be capable of selectively restricting and allowing rotation of the fourth member in accordance with movement of the third member.

Linear dual actuator for lying or sitting furniture having at least two sections (2,3), which with one end is rotatably embedded in the article of furniture and where each section (2,3) with an arm (5,7) secured to a pivot shaft (4,6) can be adjusted by means of the linear dual actuator. The dual actuator comprises a housing (8) with a drive at each end, which comprises an electric motor (11), which through a transmission (12) is in driving connection with a spindle (13). On the spindle (13) is arranged an activation element (14) with a spindle nut in engagement with the spindle (13), where the activation element (14) can be brought into engagement with the arm (5,7) for adjusting the sections (2,3). In case of power failure there is the problem that the back rest and leg rest section cannot be lowered to a plane level, which can make the bed uncomfortable or completely impossible to sleep in. This problem is solved in that a rotating element in the drives comprises a connection (21), which is accessible from the outer side of the housing (8) for connecting a tool, e.g. an Allen key (22) for driving the respective drives for the back rest and leg rest section (2,3) for lowering of these to a horizontal position.