The valve core is installed in the inner hole of the upper end of the inner tube valve nozzle and is a one-way valve to keep the seal. Install the valve core to slowly twist, can not be too hard on too tight (no leakage can be) , so as to avoid the valve core thread buckle, spring failure, rubber gasket loss of sealing; At the same time pay attention to the valve mouth and the valve core activities tappet flush, easy to measure the barometer and wear valve cap. Before inflating, the valve nozzle (including valve core) should be wiped clean to prevent dirt from entering the inner tube. When inflating, the valve core should not be taken out or relaxed, as it is often screwed out and screwed in, the rubber sealing ring will gradually lose its effect. When measuring the air pressure, the barometer should be in close contact with the valve core stem valve, do not force too much, so as to avoid damage to the machine, after filling should check whether the valve is leaking air, when the leak is found, should be timely repair or replacement of new parts, do not screw hard, to prevent valve core break or next time difficult to remove. Must insist on wearing all the valve cap, and to tighten reliably to prevent dust, dirt into the mouth, causing blockage and rust, so that the spring failure caused slow air leakage.