A full journal bearing has a journal diameter of 25 mm, with a unilateral tolerance of −0.03 mm. The bushing bore has a diameter of 25.03 mm and a unilateral tolerance of 0.04 mm. The l/d ratio is 1/2. The load is 1.2 kN and the journal runs at 1100 rev/min. If the average viscosity is 55 mPa · s, find the minimum film thickness, the power loss, and the side flow for the minimum clearance assembly.
The minimum film thickness for the bearing.
The power loss for the bearing.
The side flow for the minimum clearance assembly.
Answer to Problem 1P
The minimum film thickness for the bearing is
The power loss for the bearing is
The side flow for the minimum clearance assembly is
Explanation of Solution
Write the expression for the minimum radial clearance.
Here, the minimum radial clearance is
Write the expression for the radius of the journal bearing.
Here, the radius of the journal bearing is
Write the expression for the radial clearance ratio of the bearing.
Here, the radial clearance ratio of the bearing is
Write the expression for the number of revolution per second.
Here, the number of revolution per second is
Write the expression for the characteristic pressure.
Here, the characteristic pressure of the bearing is
Write the expression for the bearing characteristic number.
Here, the bearing characteristic number is
Write the expression for the minimum thickness of the film.
Here, the minimum thickness of the film is
Write the expression for the coefficient of the friction.
Here, the coefficient of the friction is
Write the expression for the parasitic friction torque.
Here, the parasitic friction torque is
Write the expression for the heat loss of the journal bearing.
Here, the heat loss of the journal bearing is
Write the expression for the volumetric oil flow rate in to the bearing.
Here, the volumetric oil flow rate in to the bearing is
Write the expression for the volumetric side flow leakage out of the bearing.
Here, the volumetric side flow leakage out of the bearing is
Conclusion:
Substitute
Substitute
Substitute
Substitute
Substitute
Substitute
Substitute
Thus, the minimum film thickness for the bearing is
Substitute
Substitute
Substitute
Thus, the power loss for the bearing is
Substitute
Substitute
Thus, the side flow for the minimum clearance assembly is
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Chapter 12 Solutions
Shigley's Mechanical Engineering Design (McGraw-Hill Series in Mechanical Engineering)
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