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In an oil-lubricated journal bearing, coefficient of friction between the journal and the bearing.
- a)Remains constant at all speeds.
- b)is minimum at zero speed and increases monotonically with increase in speed.
- c)is maximum at zero speed and decreases monotonically with increase in speed.
- d)becomes minimum at an optimum speed and then increases with further increase in speed.
Correct answer is option 'D'. Can you explain this answer?
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In an oil-lubricated journal bearing, coefficient of friction between ...
Friction in Oil-Lubricated Journal Bearing
Friction is a significant factor in the performance of oil-lubricated journal bearings. The coefficient of friction between the journal and the bearing is affected by various factors, such as the speed of the journal, the viscosity of the lubricant, the surface roughness of the journal and the bearing, and the pressure distribution in the lubricating film. The coefficient of friction can be defined as the ratio of the frictional force between the journal and the bearing to the normal force between them.
Behavior of Coefficient of Friction with Speed
The behavior of the coefficient of friction with speed depends on the operating conditions and the design of the bearing. Generally, the coefficient of friction decreases with an increase in speed due to the following reasons:
- The viscosity of the lubricant decreases with an increase in temperature, and the shear rate increases with an increase in speed, leading to a decrease in the viscosity of the lubricant.
- The pressure distribution in the lubricating film changes with an increase in speed, and the pressure peaks shift towards the center of the bearing, reducing the frictional force between the journal and the bearing.
However, the coefficient of friction may not always decrease with an increase in speed and may reach a minimum value at an optimum speed and then increase with further increase in speed. This behavior is due to the following reasons:
- At low speeds, the lubricating film is thick, and the pressure distribution is more uniform, resulting in a high coefficient of friction.
- At high speeds, the lubricating film is thin, and the pressure distribution is non-uniform, resulting in a high coefficient of friction.
- At an optimum speed, the lubricating film is neither too thick nor too thin, and the pressure distribution is more uniform, resulting in a low coefficient of friction.
Conclusion
In conclusion, the coefficient of friction between the journal and the bearing in an oil-lubricated journal bearing becomes minimum at an optimum speed and then increases with further increase in speed due to the changes in the viscosity of the lubricant and the pressure distribution in the lubricating film.
Friction is a significant factor in the performance of oil-lubricated journal bearings. The coefficient of friction between the journal and the bearing is affected by various factors, such as the speed of the journal, the viscosity of the lubricant, the surface roughness of the journal and the bearing, and the pressure distribution in the lubricating film. The coefficient of friction can be defined as the ratio of the frictional force between the journal and the bearing to the normal force between them.
Behavior of Coefficient of Friction with Speed
The behavior of the coefficient of friction with speed depends on the operating conditions and the design of the bearing. Generally, the coefficient of friction decreases with an increase in speed due to the following reasons:
- The viscosity of the lubricant decreases with an increase in temperature, and the shear rate increases with an increase in speed, leading to a decrease in the viscosity of the lubricant.
- The pressure distribution in the lubricating film changes with an increase in speed, and the pressure peaks shift towards the center of the bearing, reducing the frictional force between the journal and the bearing.
However, the coefficient of friction may not always decrease with an increase in speed and may reach a minimum value at an optimum speed and then increase with further increase in speed. This behavior is due to the following reasons:
- At low speeds, the lubricating film is thick, and the pressure distribution is more uniform, resulting in a high coefficient of friction.
- At high speeds, the lubricating film is thin, and the pressure distribution is non-uniform, resulting in a high coefficient of friction.
- At an optimum speed, the lubricating film is neither too thick nor too thin, and the pressure distribution is more uniform, resulting in a low coefficient of friction.
Conclusion
In conclusion, the coefficient of friction between the journal and the bearing in an oil-lubricated journal bearing becomes minimum at an optimum speed and then increases with further increase in speed due to the changes in the viscosity of the lubricant and the pressure distribution in the lubricating film.
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In an oil-lubricated journal bearing, coefficient of friction between ...
According to my perspective kinetic friction remains same but dynamic friction may vary with speed
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In an oil-lubricated journal bearing, coefficient of friction between the journal and the bearing.a)Remains constant at all speeds.b)is minimum at zero speed and increases monotonically with increase in speed.c)is maximum at zero speed and decreases monotonically with increase in speed.d)becomes minimum at an optimum speed and then increases with further increase in speed.Correct answer is option 'D'. Can you explain this answer?
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In an oil-lubricated journal bearing, coefficient of friction between the journal and the bearing.a)Remains constant at all speeds.b)is minimum at zero speed and increases monotonically with increase in speed.c)is maximum at zero speed and decreases monotonically with increase in speed.d)becomes minimum at an optimum speed and then increases with further increase in speed.Correct answer is option 'D'. Can you explain this answer? for Mechanical Engineering 2024 is part of Mechanical Engineering preparation. The Question and answers have been prepared according to the Mechanical Engineering exam syllabus. Information about In an oil-lubricated journal bearing, coefficient of friction between the journal and the bearing.a)Remains constant at all speeds.b)is minimum at zero speed and increases monotonically with increase in speed.c)is maximum at zero speed and decreases monotonically with increase in speed.d)becomes minimum at an optimum speed and then increases with further increase in speed.Correct answer is option 'D'. Can you explain this answer? covers all topics & solutions for Mechanical Engineering 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for In an oil-lubricated journal bearing, coefficient of friction between the journal and the bearing.a)Remains constant at all speeds.b)is minimum at zero speed and increases monotonically with increase in speed.c)is maximum at zero speed and decreases monotonically with increase in speed.d)becomes minimum at an optimum speed and then increases with further increase in speed.Correct answer is option 'D'. Can you explain this answer?.
In an oil-lubricated journal bearing, coefficient of friction between the journal and the bearing.a)Remains constant at all speeds.b)is minimum at zero speed and increases monotonically with increase in speed.c)is maximum at zero speed and decreases monotonically with increase in speed.d)becomes minimum at an optimum speed and then increases with further increase in speed.Correct answer is option 'D'. Can you explain this answer? for Mechanical Engineering 2024 is part of Mechanical Engineering preparation. The Question and answers have been prepared according to the Mechanical Engineering exam syllabus. Information about In an oil-lubricated journal bearing, coefficient of friction between the journal and the bearing.a)Remains constant at all speeds.b)is minimum at zero speed and increases monotonically with increase in speed.c)is maximum at zero speed and decreases monotonically with increase in speed.d)becomes minimum at an optimum speed and then increases with further increase in speed.Correct answer is option 'D'. Can you explain this answer? covers all topics & solutions for Mechanical Engineering 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for In an oil-lubricated journal bearing, coefficient of friction between the journal and the bearing.a)Remains constant at all speeds.b)is minimum at zero speed and increases monotonically with increase in speed.c)is maximum at zero speed and decreases monotonically with increase in speed.d)becomes minimum at an optimum speed and then increases with further increase in speed.Correct answer is option 'D'. Can you explain this answer?.
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