Abstract: A crane comprising a traveling body and a turning body turnably supported by the traveling body, the crane performing power feeding and communication between the traveling body and the turning body. The traveling body is provided with: a power supply; a lower controller which controls the traveling body and transmits power to the devices included in the traveling body; and a lower transmitter-receiver which wirelessly transmits and receives the power and data signal from the power supply. The turning body is provided with: an upper controller which controls the turning body and transmits power to the devices included in the turning body; and an upper transmitter-receiver which wirelessly transmits and receives the power and data signal to and from the lower transmitter-receiver.

Abstract: A crane comprising a traveling body and a turning body turnably supported by the traveling body, the crane performing power feeding and communication between the traveling body and the turning body. The traveling body is provided with: a power supply; a lower controller which controls the traveling body and transmits power to the devices included in the traveling body; and a lower transmitter-receiver which wirelessly transmits and receives the power and data signal from the power supply. The turning body is provided with: an upper controller which controls the turning body and transmits power to the devices included in the turning body; and an upper transmitter-receiver which wirelessly transmits and receives the power and data signal to and from the lower transmitter-receiver.

Abstract: Provided is a hydraulic cylinder using oil pressure, etc., the hydraulic cylinder being configured so that the thickness of a head cover, etc. is reduced so that the hydraulic cylinder is lighter and has a small overall length. A head cover (3) which constitutes an end of a cylinder (1) and a cylinder tube (2) which constitutes the cylindrical portion of the cylinder (1) are welded together by a laser beam applied from the outside radially of the cylinder tube (2) toward the inside radially of the cylinder tube (2).