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)

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

Answer: (C)