A telescoping crane boom having a rotary locking mechanism. A motor drives a rotating element about an axis parallel to the axis of the crane boom. The rotation of the rotating member causes a pin to selectively lock and unlock sections of the telescoping crane boom.

A boom extension and contraction mechanism for a crane apparatus includes: a flow passage switching mechanism that switches a flow passage of the hydraulic oil between the cylinder-to-boom connection switching cylinder side and the boom member connection switching cylinder side; a hose reel configured to reel out a hydraulic hose as a telescopic cylinder is extending, and to reel off the hydraulic hose as the telescopic cylinder is contracting; a cable used to supply power and transmit a signal between a swivel base and a boom; and a cord reel configured to reel out the cable as the telescopic cylinder is extending and to reel off the cable as the telescopic cylinder is contracting. The code reel and the hose reel are arranged on the base in a direction in which the boom extends and contracts.

The work machine includes: a telescoping actuator that moves a first boom in the telescoping direction with respect to a second boom; an electrical drive source that is disposed in a movable portion of the telescoping actuator; a first connection mechanism that switches a connection state between the telescoping actuator and the first boom on the basis of the power of the electrical drive source; a second connection mechanism that switches a connection state between the first boom and the second boom on the basis of the power of the electrical drive source; and a torque limiter that is disposed between the electrical drive source and the first connection mechanism or the second connection mechanism, the torque limiter maintaining, at a predetermined value or less, a load acting on a mechanical element constituting a power transmission path from the electrical drive source.

This expansion device is an expansion device that expands and contracts an boom, the expansion device including: a first hydraulic source that discharges a first working fluid; an expandable cylinder that has a fixed part and a movable part and is operated by the first working fluid; a second hydraulic source that is provided to the movable part, discharges the second working fluid, and is a separate hydraulic source from the first hydraulic source; a first connecting mechanism that is operated by the second working fluid and switches between a connected state and a disconnected state of the first boom element and the movable part; and a second connecting mechanism that is operated by the second working fluid and switches between a connected state and a disconnected state of the first boom element and the second boom element.

A work machine includes: an actuator that extends and retracts a telescopic boom; an electric drive source that is provided in the actuator and drives using power supplied from a power source; an operating unit that operates based on power of the electric drive source; and a joint that has a drive-side element fixed to a first transmission shaft that rotates on the basis of the power of the electric drive source and a driven-side element fixed to a second transmission shaft connected to the operating unit, the joint being able to take a transmission state in which both the drive-side element and the driven-side element rotate and a non-transmission state in which only either the drive-side element or the driven-side element rotates.

This work machine includes: an actuator that extends and retracts a telescopic boom; an electric drive source that is provided in the actuator and drives using power supplied from a power source; an operating unit that operates based on power of the electric drive source; an electric circuit capable of switching between a drive state in which a supply of power from the power source to the electric drive source is allowed to drive the electric drive source, and a braking state in which the supply of power from the power source to the electric drive source stops to generate a braking force to be applied to the electric drive source; and a control unit that controls the switching between the drive state and the braking state.

A telescoping jib system of a mobile crane having a basic telescoping jib and an additional telescoping jib that can be retracted and extended via a telescoping cylinder with a securing and locking unit. In order to improve the telescoping jib system, it is proposed that a securing unit is arranged on a tip of the telescoping cylinder, the securing unit comprises exclusively at least one driving bolt, via which an additional telescoping jib separate from the basic telescoping jib can be retracted into the basic telescoping jib. The invention also relates to a method for lengthening a basic telescoping jib of a mobile crane by means of an additional telescoping jib to form a telescoping jib system.

A telescoping jib of a mobile crane having a basic box and a plurality of inner boxes that can each be extended from a retraction position to an extension position and that can be locked and unlocked together in the respective retraction position or extension positions by means of bolting holes, which are arranged in the basic and inner boxes, and associated locking bolts. In order to provide a telescoping jib of a mobile crane which can be easily unlocked in an emergency, it is proposed that, in the retraction position of the basic and inner boxes, the bolting holes for the extension positions are aligned with one another.

Telescoping boom systems, devices, and methods are provided in accordance with various embodiments. For example, some embodiments include zero dead band telescoping boom systems, devices, and methods. Embodiments in general include hard stop preloading mechanisms for telescoping booms with multiple tube segments. Some embodiments provide components that facilitate the deployment sequencing of the multiple tube segments along with facilitating preloading of the multiple tube segments of a telescoping boom. The tools and techniques provided may be integrated into the multiple tube segments rather than being provided as a separate system. Some embodiments allow for precise deployment of the multiple tube segments of the telescoping boom systems, devices, and methods.

A telescoping jib system of a mobile crane having a basic telescoping jib and an additional telescoping jib that can be retracted and extended via a telescoping cylinder with a securing and locking unit. In order to improve the telescoping jib system, it is proposed that a securing unit is arranged on a tip of the telescoping cylinder, the securing unit comprises exclusively at least one driving bolt, via which an additional telescoping jib separate from the basic telescoping jib can be retracted into the basic telescoping jib. The invention also relates to a method for lengthening a basic telescoping jib of a mobile crane by means of an additional telescoping jib to form a telescoping jib system.