An actuator includes M supports to support the rotary shaft, M being an integer equal to or more than 2; and M speed reducers. The Nth support out of the M supports is located at the opposite side of the moving body across the (N1)th support, N being an integer which is equal to or more than 2 and equal to or less than M. The first speed reducer is connected to the moving body and the first support, receives a movement of the moving body in the axial direction as an input and drives the first support with a reduced drive force that is reduced from the input, and the Nth speed reducer is connected to the (N1)th support and the Nth support, receives a movement of the (N1)th support in the axial direction as an input and drives the Nth support with a reduced drive force.

An electric actuator comprises a housing and an output shaft reciprocatingly received by the housing. There is a screw assembly disposed within the housing and coupled to the output shaft. The screw assembly includes a plurality of annular rollers and a central screw received by the annular rollers. The annular rollers are rotatable about the central screw. There is a motor which includes a stator and a rotor. The rotor has an inner bore which engages the annular rollers. Rotation of the rotor causes the central screw to translate axially relative to the rotor and the output shaft to reciprocate relative to the housing.

In a spindle system with a hollow spindle for a linear actuator, the linear actuator has a telescopic tube system including an outer tube and at least one inner tube arranged coaxially with the outer tube and at least partially surrounded by the outer tube. A bearing is arranged to transmit axial forces between the hollow spindle and the outer tube. The hollow spindle at least partially surrounds an inner shaft of the spindle system and is connected to the inner shaft of the spindle system by one or more tappets of a positive and axially displaceable shaft-hub connection. The hollow spindle has a bearing seat for the bearing and an external thread on an outer side.

A linear drive includes an output member which is linearly movable with respect to a drive housing, and which has a spindle nut and a hollow output rod connected thereto. The output member is linearly displaceable by means of a rotationally drivable threaded spindle, which is inserted through the spindle nut into the output rod. To support the threaded spindle, a support apparatus is provided at its anterior end section, which has a rolling bearing and a sliding sleeve seated thereon. The sliding sleeve is divided into sliding sleeve segments, which are connected to one another by resilient joints and are each prestressed with a support area section against the inner peripheral surface of the output rod.

A linear guide system including a first rail element and a second rail element mounted so as to be linearly displaceable relative to one another in and against a pull-out direction. A spindle drive includes a threaded spindle and a spindle nut running on the threaded spindle. The threaded spindle is mounted rotatably about a spindle axis on the first rail element or on a device fixed in or against the pull-out direction relative to the first rail element. The spindle nut is fixed in and against the pull-out direction on the second rail element, so that the spindle nut moves along the threaded spindle during a rotational motion of the threaded spindle and entrains the second rail element. The second rail element carries a spindle bearing fixed in or against the pull-out direction relative to the second rail element. that is arranged and positioned such that the spindle bearing guides the threaded spindle relative to the second rail element.

A linear drive includes an output member which is linearly movable with respect to a drive housing, and which has a spindle nut and a hollow output rod connected thereto. The output member is linearly displaceable by means of a rotationally drivable threaded spindle, which is inserted through the spindle nut into the output rod. To support the threaded spindle, a support apparatus is provided at its anterior end section, which has a rolling bearing and a sliding sleeve seated thereon. The sliding sleeve is divided into sliding sleeve segments, which are connected to one another by resilient joints and are each prestressed with a support area section against the inner peripheral surface of the output rod.