Intro to Millwright Practice Exam

Which type of threading consists of two separate ridges and grooves originating from opposite sides?

1. Single Start

2. Double Start

3. Triple Start

4. Quadruple Start

The correct answer is: Double Start

The correct answer is double start threading. This type of threading is characterized by having two distinct ridges and grooves that originate from opposite sides of the thread. As a result, double start threads have a higher lead compared to single start threads, which only have one ridge and groove. This allows for faster advancement of the screw or bolt with each complete turn, making double start threads particularly useful in applications where quick engagement or disengagement is necessary. The structure of double start threads allows them to distribute loads more evenly and reduce the risk of cross-threading, which can lead to mechanical issues. This design is effective in scenarios requiring adjustments or movements that need to be performed swiftly and with precision, such as in machinery where a secure connection and rapid action are critical. Other threading types, such as single, triple, and quadruple start, have different configurations which would not provide the same benefits associated with the dual ridge design of double start threads. Single start threads, for instance, have only one ridge and groove, while triple and quadruple start threads increase the number of ridges and grooves even further, which impacts their application and function.