The present invention relates to a telescopic device of single-cylinder latch type and a crane. The telescopic device of single-cylinder latch type is applied to a telescopic boom system and includes: a telescopic cylinder, for driving telescopic boom sections of the telescopic boom system to execute a telescopic action relative to a basic boom section; double boom pin structures, arranged on both sides of the tails of the telescopic boom sections to lock and unlock the telescopic boom sections; an boom pin pulling and plugging mechanism, arranged on the cylinder barrel of the telescopic cylinder to execute pulling and plugging operations on the double boom pin structures; and a cylinder pin structure and a cylinder pin cylinder, both arranged on the cylinder barrel of the telescopic cylinder and to lock and unlock the cylinder barrel of the telescopic cylinder and the telescopic boom sections. In the present invention, the double boom pin structures are arranged on both sides of the tails of the telescopic boom sections, compared with the existing upper boom pin solution, the double boom pin structures in the present invention are arranged on both sides of the telescopic boom sections, so that the stress is more uniform compared with a structure which is singly arranged on the upper side of a telescopic boom, and the influence of flexural deformation of a telescopic boom on the position of a pin hole and the stress of an boom pin is reduced.

This work machine comprises: a plurality of booms that extend and retract with the power of an actuator; a first pin that is moved by a first spring to connect adjacent booms and is moved by power of a motor to release a connection of the adjacent booms; a second pin that is moved by a second spring to connect the boom and the actuator and is moved by power of the motor to release a connection of the boom and the actuator; and a circuit that is configured so that when the first pin is moved by the first spring or when the second pin is moved by the second spring, a current based on motor idling caused by the movement of the first pin or second pin is not generated.

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 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 control device that controls operation of the electrical drive source. The control device executes motor assist processing of operating the electrical drive source when the first fixing pin and/or the second fixing pin is restored by biasing force.

This work machine includes: a plurality of booms that extend and contract by means of power of an actuator; a boom coupling pin which is supported by the booms, moves in the entering direction by means of a spring to turn into an entering state in which adjacent booms are coupled, and moves in the pulling direction by means of power of a motor to turn into a pulling state in which the coupling is released; and a manual operation member inserted into the boom coupling pin and disposed coaxially with the boom coupling pin. As the manual operation member rotates on the basis of the manual operation of an operator, the boom coupling pin moves in the pulling direction together with the manual operation member, and the coupling between adjacent booms is released.

The disclosure relates to a hydraulic system for pressure supply of a hydraulic actuator, comprising a double-acting hydraulic cylinder having two pressure chambers, and a rapid traverse device integrated into a valve unit and configured to hydraulically interconnect the two pressure chambers in a rapid traverse mode and hydraulically separate the two pressure chambers in a normal traverse mode. The valve unit connects to the pressure chambers via first and second connections and comprises a third connection for applying pressure via a hydraulic pump. A displaceably mounted shift piston separates the first and second connections in normal traverse position and connects them, separated from the third connection, in rapid traverse position. The valve unit integrates a preload device having a switchable preload element configured to separate the third connection from the second connection in a locking position, thereby locking the pressure chamber connected to the second connection towards the outside.

The present invention relates to a locking head for telescoping cylinders of a telescopic boom, which has a plurality of telescopic boom portions, and a housing which comprises at least one bolt-like cylinder locking body, which can be moved in and out of the housing in order to lock the locking head with a telescopic boom portion, and at least one bolt-like telescope locking body, which can be moved in and out of the housing in order to release the telescopic boom portion for a telescoping movement. The locking head has at least one electric actuator which is designed to actuate the at least one cylinder locking body and/or the at least one telescope locking body.