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

• A. T₁/T₂ = μ. θ. n
• B. T₁/T₂ = (μ θ)n
• C. T₁/T₂ = [(1 + μ tanθ)/(1 - μ tanθ)]n
• D. T₁/T₂ = [(1 - μ tanθ)/(1 + μ tanθ)]n

Answer: (C)