The present disclosure includes a telescopic bearing assembly capable of withstanding predetermined bending loads and at the same time is fully telescopically extendable, while minimizing a wall thickness (t) in each of tubular bearing sections of an associated telescopic arm. Additionally, the present disclosure includes a mobile hydraulic telescopic crane with a telescopic arm with such an assembly.

The present disclosure includes a telescopic bearing assembly capable of withstanding predetermined bending loads and at the same time is fully telescopically extendable, while minimizing a wall thickness (t) in each of tubular bearing sections of an associated telescopic arm. Additionally, the present disclosure includes a mobile hydraulic telescopic crane with a telescopic arm with such an assembly.

A slew bearing includes a stationary bearing ring to be fixed to a base, and a moveable bearing ring to be fixed to a moveable object, wherein the stationary bearing ring and the moveable bearing ring are configured to enable rotation of the moveable bearing ring relative to the stationary bearing ring about a rotation axis. A main axial bearing and an auxiliary bearing are provided between the stationary bearing ring and the moveable bearing ring, wherein the moveable bearing ring includes one or more main portions and one or more auxiliary portions, which one or more main portions are moveable relative to the one or more auxiliary portions between an operational position, in which the main axial bearing transfers the axial loads between moveable bearing ring and stationary bearing ring, and a raised maintenance position, in which the auxiliary axial bearing transfers the axial loads between moveable bearing ring and stationary bearing ring and the main bearing is allowed to be inspected and/or maintained so that the slew bearing during inspection and/or maintenance is still operational.

In a state where a slewing stop operation is input, in a first state where a slewing command value is equal to or greater than an actual slewing speed, a drive unit stops outputting a torque command value, and a free-run state occurs. In the first state, a command value calculation unit decreases the slewing command value at a first inclination. Meanwhile, in the state where the slewing stop operation is input, in a second state where the slewing command value is less than the actual slewing speed, the command value calculation unit decreases the slewing command value at a second inclination that is gentler than the first inclination.

The present disclosure relates to an apparatus and to a method for controlling a crane slewing gear. The apparatus comprises a hydraulic motor for driving the slewing gear and for braking the slewing gear from a rotational movement. The slewing gear is kept stationary via a holding brake. A hydraulic brake circuit for controlling the holding brake, a load sensing device for measuring a load instantaneously taken up by the crane, and an orientation sensing device for measuring an instantaneous orientation of the crane and/or of at least one crane component are furthermore provided. In accordance with the disclosure, a hydraulic limitation circuit is provided by means of which a hydraulic pressure applied to the motor can be limited to a specific limit value. A control unit is furthermore provided that determines a maximum permitted torque and/or a parameter derived therefrom for a current slewing gear movement.

The present disclosure relates to an apparatus and to a method for controlling a crane slewing gear. The apparatus comprises a hydraulic motor for driving the slewing gear and for braking the slewing gear from a rotational movement. The slewing gear is kept stationary via a holding brake. A hydraulic brake circuit for controlling the holding brake, a load sensing device for measuring a load instantaneously taken up by the crane, and an orientation sensing device for measuring an instantaneous orientation of the crane and/or of at least one crane component are furthermore provided. In accordance with the disclosure, a hydraulic limitation circuit is provided by means of which a hydraulic pressure applied to the motor can be limited to a specific limit value. A control unit is furthermore provided that determines a maximum permitted torque and/or a parameter derived therefrom for a current slewing gear movement.

A slewing frame of a work machine and a method of assembling a slewing frame of a work machine where the slewing frame is separable into at least two front and rear members, and an operation of connecting these two members can be easily performed. A slewing frame is separable into a front frame and a rear frame. When a pin fitting portion of a rear frame is fitted on a positioning pin of a front frame, and the rear frame is rotated downward, at a position where a front pin hole and a rear pin hole are aligned with each other, a contact portion of the rear connecting portion is brought into contact with a rotation preventing portion. As a result, a connecting pin can be easily inserted into the front pin hole and the rear pin hole.

A slewing frame of a work machine and a method of assembling a slewing frame of a work machine where the slewing frame is separable into at least two front and rear members, and an operation of connecting these two members can be easily performed. A slewing frame is separable into a front frame and a rear frame. When a pin fitting portion of a rear frame is fitted on a positioning pin of a front frame, and the rear frame is rotated downward, at a position where a front pin hole and a rear pin hole are aligned with each other, a contact portion of the rear connecting portion is brought into contact with a rotation preventing portion. As a result, a connecting pin can be easily inserted into the front pin hole and the rear pin hole.

A device includes a bevel pinion meshed to a bevel ring in rigid fixation with a pinion gear engaged with a slew ring to control rotation of the slew ring. A rotation sensor provides an electrical output corresponding to a rotational position of an input gear of the rotation sensor. A reduction gearing system interposes the bevel ring and the input gear of the rotation sensor. The gearing reduction system provides a reduction ratio enabling the rotation sensor to determine rotational position of the slew ring.

A device includes a bevel pinion meshed to a bevel ring in rigid fixation with a pinion gear engaged with a slew ring to control rotation of the slew ring. A rotation sensor provides an electrical output corresponding to a rotational position of an input gear of the rotation sensor. A reduction gearing system interposes the bevel ring and the input gear of the rotation sensor. The gearing reduction system provides a reduction ratio enabling the rotation sensor to determine rotational position of the slew ring.