How is a lower pair classified in mechanics_____________________?
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Answer: B. closed pair
Explanation
Lower pairs feature extended surface contact between their two elements, constraining relative motion effectively. Mechanical design enclosures or geometric constraints lock these mating surfaces together to form a closed pair. This surface contact distributes loads efficiently, making lower pairs ideal for high-load power transmission. Kinematic pairs are classified into lower pairs and higher pairs based on the geometry of their contact area. Examples of lower pairs include pin joints, sliding prismatic joints, and threaded screw mechanisms. A closed pair ensures that relative motion follows a strictly constrained path without separating under normal loads.
Heavy industrial presses and hydraulic actuators rely on lower pairs to withstand tremendous operating loads safely. Machine tool slide ways use lower pairs to maintain precise linear guidance during high-precision cutting operations. Understanding pair classification helps engineers select appropriate bearing types and lubrication methods. Open pairs lack mechanical fastening between elements, whereas lower pairs are typically enclosed and constrained. Sliding pairs represent a specific type of lower pair rather than the broad overarching classification category. Point contact pairs define higher kinematic pairs, such as ball bearings or gear teeth, not lower pairs.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
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