Patent attributes
A drain bolt configured to be forcibly withdrawn from an oil tank. The drain bolt includes a fastening screw section integrally formed on one side of a head and an elastic screw section coupled to the distal end of the fastening screw section. The elastic screw section formed of a soft material has extension threads continuous to threads of the fastening screw section. The color of the elastic screw section is distinguishable from the color of the fastening screw section. The elastic screw section can be separated from a female thread portion of the oil tank due to force applied by a user or a mechanic. Even when the fastening screw section is separated from the female thread portion of the oil tank, the sealing ability between the drain bolt and the female thread portion is maintained due to the elastic screw section remaining in the meshed position.
