A rotating shaft supported inside a bearing represents what classification of kinematic pair________________?
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Answer: A. lower pair
Explanation
A rotating shaft supported inside a journal bearing features surface contact between the mating cylindrical elements. This extensive surface contact area classifies the shaft and bearing assembly as a lower kinematic pair. Lower pairs distribute applied loads across a wide surface area, reducing contact stresses significantly. Lower pairs are defined by geometric surface contact between the two connected machine elements. Journal bearings support radial loads while allowing smooth rotational motion of the spinning shaft. Lubricating oil films are maintained between the shaft and bearing surface to prevent metal to metal contact.
Industrial gearboxes and electric motors rely heavily on journal bearings and rotating shafts as lower pairs. Proper clearance design in lower pair bearings ensures stable hydrodynamic lubrication at high speeds. Excessive radial loads can break down the oil film in a bearing, leading to immediate frictional overheating. Higher pairs involve point or line contact, such as meshing gear teeth or ball bearing rolling elements. Spherical pairs involve ball and socket joints that permit rotational movement in multiple planes. Cylindrical pair terminology is sometimes used, but lower pair is the primary classification based on contact.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
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