two types of lock screws for the toy cars male screw and female screw

There are two types of lock screws for the toy cars: male screw and female screw

When used in pairs, there is no locking function if they are separated.
There are male and female screw for the lock screws of the toy cars. The principle of locking is to use the non-concentricity of the conical convex and concave platform to squeeze and friction lock. The convex and concave platforms are 

male and female. When used in pairs, there is no locking function when separated. Baby carriage pair lock screws are generally used to fix tires, and one male and one female pair locks to achieve fastening


A screw is a tool that uses the physics and mathematics of the oblique circular rotation of the object and the friction force to gradually tighten the utensils. Screw is a general term for fasteners, a daily oral language. Screws are 

indispensable industrial necessities in daily life: extremely small screws used in cameras, glasses, clocks, electronics, etc.; general screws used in televisions, electrical products, musical instruments, furniture, etc.; as for 

engineering, construction, and bridges, large-scale screws are used. Screws and nuts; transportation equipment, airplanes, trams, cars, etc. are used for both large and small screws. Screws have important tasks in industry. As long as 

there is industry on the earth, the function of screws will always be important. The screw is a common invention in people's production and life for thousands of years. According to the application field, it is the first invention of 

mankind.