MEE474 Chapter 12

MEE474 Chapter 12

By Professor Tomforde

Multiple Choice

The symbol for minimum film thickness

• $$h_0$$  

• $$t_{\min}$$  

• $$t_{film}$$  

• $$f_{thicc}$$  

This is a dimensionless variable, the ratio of film thickness to minimum clearance.

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--ProTip: Don't forget to multiply this value by c to get h₀!

Fig 12-15​

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Multiple Choice

The bearing characteristic number, or S, is also called the

• Sommerfeld number

• Reynolds number

• viscosity

• coefficient of friction

The y-axis gives you the flow ratio, or Q_s/Q.

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This is a percentage value.

Fig 12-19

Multiple Choice

The minimum clearance for a bushing bore of 25.03 mm and a journal diameter of 25 mm

• 0.015 mm

• 0.03 mm

• -0.03 mm

• 0

Careful!

The clearance value is a radius so don't forget to divide the diameter difference by 2. ​

Tip: This should be the minimum number possible, so the difference between minimum bushing and the maximum diameter.

Draw

Identify on the graph: Sommerfeld number of 0.2 and l/d =0.5.

Open Ended

Why do we care about the torque value when we look at engine specs?