Cylinder

The utility model provides a cylinder. This cylinder includes the cylinder body, piston axle, piston and centre gripping subassembly. Be provided with the piston shaft hole on this cylinder body, reach and the communicating piston chamber in this centre gripping hole with the communicating centre gripping hole in this piston shaft hole. A this piston shaft hole and a gas pocket communicate with each other. This piston axle sets up in this piston shaft hole. This piston sets up in this piston intracavity, splits into two independent cavitys with this piston chamber, and these two cavitys communicate with each other with a gas pocket respectively. This centre gripping subassembly pin joint sets up in this centre gripping downtheholely to offset with this piston. This centre gripping subassembly allows this piston axle therefrom to pass. This piston axle can be stretched out this cylinder body by air pressure drive. This piston can be by air pressure drive to a lateral movement of being close to this centre grip