Understanding Machine Pairs

In mechanics, machine elements are often classified based on the type of constraint they provide, forming various 'pairs'. These are broadly categorized into lower pairs and higher pairs.

Defining Lower and Higher Pairs

• Lower Pair: Formed when two machine elements have surface contact. This contact involves area.
• Higher Pair: Formed when two machine elements have line or point contact.

Analysis of Options

Let's analyze the given options based on their contact type:

• Sliding Pair: Occurs when one surface slides over another (e.g., a piston in a cylinder). This is a lower pair due to surface contact.
• Turning Pair: Occurs when one element rotates relative to another about a fixed axis (e.g., a shaft in a bearing). This is also a lower pair due to surface contact.
• Rolling Pair: Occurs when one element rolls on another (e.g., a wheel on a road, ball bearings). This contact is typically a line contact (like cylinder on cylinder) or point contact (like sphere on sphere).

Conclusion on Higher Pair Formation

Since a rolling pair involves line or point contact, it fits the definition of a higher pair. Sliding and turning pairs involve surface contact, making them lower pairs.

Therefore, the formation of a rolling pair leads to a higher pair.