Machine Design
In a band and block brake, the ratio of tensions on the tight and slack sides of band is given by (where μ = Coefficient of friction between the blocks and the drum, θ = Semi-angle of each block subtending at the centre of drum, and n = Number of blocks)

T₁/T₂ = μθ × n
T₁/T₂ = [(1 - μ tanθ)/ (1 + μ tanθ)]n
T₁/T₂ = (μθ)n
T₁/T₂ = [(1 + μ tanθ)/ (1 - μ tanθ)]n

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Machine Design
According to I.B.R., when the thickness of boiler shell (t) is greater than 8 mm, then the diameter of rivet hole (d) is obtained by

Equating shearing resistance to the crushing resistance of the rivets
Equating tearing resistance of the plate to the crushing resistance of the rivets
None of these
Equating tearing resistance of the plate to the shearing resistance of the rivets

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