They are more efficient, as they lose less power to fric- tion than do single-lead threads. They have larger minor diameters therefore, a bolt is stronger than one with a single thread.Ĥ. They furnish more bearing surface area than single threads.Ģ. Multiple-lead threads offer several advantages:ġ. A singlelead thread should be used for fasteners where locking power is required. Multiple threads have less holding power, and less force is produced when these screws are tightened. You may determine whether a bolt or screw is single or multiple threaded by looking at its end (Figure I-409) and counting the grooves that have been started.
Most screws and bolts have single-lead threads, which are formed by cutting one groove with a single-point tool.A double-lead thread has two grooves, a triple-lead thread has three grooves, and a quadruple-lead thread has four grooves.Double, triple, and quadruple threads are also known as multiple-lead threads. They are also used on jars and other containers. Multiple threads, though not often used, are usually found on industrial machines, valves, fire hydrants, and aircraft landing gear.
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