A control method controls a movable member of an excavator including a movable member holding a load, an actuator with electric motor and static brake, a control unit and a motion sensor unit. The static brake and electric motor generate respectively an upper threshold brake force and an upper threshold motor force. An immobilization operation provides that the static brake generates the upper threshold brake force and the electric motor is stopped. A slippage detection operation provides that the control unit detects whether an electric actuator is moving despite the static brake. If the electric actuator is moving, a motor energizing operation provides that the electric motor generates a motor force equal or superior to upper threshold brake force in a direction opposite to the slippage direction. After energizing the motor, a brake release operation provides that the control unit releases the static brake.

A swivel joint for supplying and discharging various types of fluid between the top and bottom of a rotating platform includes an outer cylinder, an intermediate cylinder, and an inner cylinder that are arranged concentrically around a central axis. The intermediate cylinder can freely rotate with respect to the outer cylinder and the inner cylinder, and a hydraulic fluid flow channel is provided between the outer cylinder and the intermediate cylinder. A hot water flow channel between the lower portion of the inner cylinder and the intermediate cylinder includes an inner annular groove formed on the inner circumferential face of the intermediate cylinder. An air flow channel between the upper portion of the inner cylinder and the intermediate cylinder includes outer annular grooves formed on the outer surface of the inner cylinder.

A swivel joint for supplying and discharging various types of fluid between the top and bottom of a rotating platform includes an outer cylinder, an intermediate cylinder, and an inner cylinder that are arranged concentrically around a central axis. The intermediate cylinder can freely rotate with respect to the outer cylinder and the inner cylinder, and a hydraulic fluid flow channel is provided between the outer cylinder and the intermediate cylinder. A hot water flow channel between the lower portion of the inner cylinder and the intermediate cylinder includes an inner annular groove formed on the inner circumferential face of the intermediate cylinder. An air flow channel between the upper portion of the inner cylinder and the intermediate cylinder includes outer annular grooves formed on the outer surface of the inner cylinder.

To improve the precision of position of a fastener hole and a seating face for mounting a counterweight, a counterweight supporting member is comprised of a support plate erected and fixed at the rear end of a revolving frame and a supporting member attached to the support plate. A cylindrical bolt fastening boss is provided on the supporting member in a manner of rotational position adjustable to the supporting plate and in which a fastener hole is formed at an eccentric position.

A shovel includes a lower traveling body, an upper swiveling body mounted to the lower traveling body, attachments including a boom attached to the upper swiveling body, an arm attached to an end of the boom, and a bucket, which is an end attachment, attached to an end of the arm, and a controller configured to select, as a straight facing target surface, one of a plurality of constituting surfaces that constitute a target construction surface based on a position of the bucket.

A shovel includes a lower traveling body, an upper turning body turnably attached to the lower traveling body, an automatic greasing device mounted on the upper turning body, and a control device configured to control the automatic greasing device. The control device is configured to control timing to start greasing by the automatic greasing device based on the past operating condition of the shovel.

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 (period TA), a drive unit (203) stops outputting a torque command value, and a free-run state occurs. In the first state, a command value calculation unit (202) decreases the slewing command value at a first inclination (K1). 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 (period after time t2), the command value calculation unit (202) decreases the stewing command value at a second inclination (K2) that is gentler than the first inclination.

Work efficiency is improved while necessary and sufficient monitoring on the surroundings of a working machine is performed. A working machine includes an undercarriage 132 on which an upperstructure 131 including a front working device is mounted in a swingable manner, and includes a surrounding monitoring device 200 that monitors surroundings. The surrounding monitoring device 200 has an information controller 161 that: sets a working region by use of terrain data and work states received from sensors detecting work states of the front working device of the working machine; calculates proximity for each of the obstacles around the working machine by use of the working regions and relative positions of each of obstacles and the working machine, the obstacles being detected by an obstacle sensor that detects obstacles around the working machine; and outputs a control instruction in accordance with the proximity.

An upper body includes a bearing seat surface that is fixed by a bearing bolt to the upper surface of a swing bearing, a swing frame that includes an intersecting side plate intersecting the bearing seat surface and is fixed to the bearing seat surface, and a force dispersing member. The force dispersing member includes at least one vertical plate extending in the up-down direction. The at least one vertical plate is fixed to a region of the bearing seat surface other than a force dispersion target region.

Lifting performance of a work machine is increased while suppressing an increase in a vehicle weight. When a slewing frame (1) is seen from a side, a first reinforcement member (11) is provided from a boom foot section (5) to a front side part of a slewing bearing (22), a second reinforcement member (12) is provided from the boom foot section (5) to a mast foot section (6), and a third reinforcement member (13) is provided from the mast foot section (6) to a rear side part of the slewing bearing (22). Furthermore, a fourth reinforcement member (14) is provided from a middle region (M) located at an upper end portion of the slewing frame (1) and above a rear portion of the slewing bearing (22) to the front side part of the slewing bearing (22), and a fifth reinforcement member (15) is provided from the middle region (M) to the rear side part of the slewing bearing (22).