Machine Design
For a shoe brake, the equivalent coefficient of friction is equal to (where μ = Actual coefficient of friction, and θ = Semi-block angle)

4μ sinθ/(2θ + sin 2θ)
2μ sinθ/(θ + sinθ)
μ sinθ/(2θ + sin 2θ)
4μ sinθ/(θ + sinθ)

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Machine Design
Set screws are

Similar to small size tap bolts except that a greater variety of shapes of heads are available
Used to prevent relative motion between parts
Slotted for a screw driver and generally used with a nut
Similar to stud

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