DIFFERENT DIAMETER CONNECTION JOINT

PROBLEM TO BE SOLVED: To reduce the size and the weight of a different diameter connection joint when the diameter of a tank lorry for distributing LP gas from the diameter of an LP inlet valve of a storage tank, and prevent the different diameter connection joint from being broken by thermal expansion of LP gas. SOLUTION: A sleeve which is energized by a spring is fitted to an outer circumference of a cylindrical body having an insertion cylinder on one end and a cylinder receiving part on the other end, a plug receiving part with a lock ball fitted to a tapered hole in the circumferential surface is fitted to the cylinder receiving part, an inner cylinder is energized by a spring against a through hole communicated with the plug receiving part and accommodated therein in a slidable manner, a cutout hole is made in an inner end of a movable cylinder which is accommodated in the insertion cylinder of the cylindrical body in an advancing/retractable manner and energized by a spring, a contact valve is provided by abutting a valve part provided on the tip of a valve rod penetrating the inner cylinder with a rear part thereof pivotably attached on a tip of the inner cylinder, a port communicated with the inside of the cylindrical body is made is a lower end of a screw hole, a gas relief hole is formed on a lower part of the screw hole with one end communicated therewith and the other end opened outside, and a plug is screwed in the screw hole in an attachable/ detachable manner.