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Stresses in Universal Knuckle Joint Formulas and Calculator

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Stresses in Universal knuckle joint formulas and calculator

Universal joints are a mechanical form of coupling, originally known as a Cardan or Hooke's coupling, is used for connecting two shafts the axes of which are not in line with each other, but which merely intersect at a point. There are many different designs of universal joints or couplings, which are based on the principle embodied in the original design.

Universal Knuckle Joint

The universal knuckle joint is a good example of the application of simple stress calculations. The various stresses which may occur are given below. Failure of the universal joint may be due to any one of the stresses exceeding the material capabilities.

Preview: Stresses in Universal Knuckle Joint Calculator

Formula Symbol declarations:

P = load
σ_t = tensile stress
σ_b = bending stress
σ_c = crushing stress
τ = shear stress
D = rod diameter
D_p = Pin diameter
D_o = eye outer diameter
a = thickness of the fork
b = the thickness of the eye

(1) Tensile Stress in Shear Pin formula:

σ_t = 4 P / ( π D² )

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(2) Tensile Stress in Universal Joint Clevis Eye Section Formula:

σ_t = P / ( ( D_o - D_p ) b )

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(3) Shear Stress in Clevis Eye Formula:

τ = P / ( ( D_o - D_p ) / b )

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(4) Tensile Stress in Clevis Fork Section:

σ_t = P / ( ( D_o - D_p ) / 2a )

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(5) Shear Stress in Fork Section Formula:

τ = P / ( ( D_o - D_p ) 2a )

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(6) Crushing Stress in Universal Joint Eye Formula:

σ_c = P / ( b D_p )

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(7) Crushing stress in fork Formula:

σ_c = P / ( 2 D_p a )

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(8) Shear Stress in Universal Joint Pin Formula:

τ = 2 P / ( π D_p² )

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(9) Bending Stress in Universal Joint Pin Formula:

σ_b = [ 4 P ( a + b ) ] / ( π D_p³ )

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(10) Crushing Stress in Pin Due to Eye Forces Formula:

σ_c = P / ( b D_p )

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(11) Crushing Stress in Pin Due to Fork Formula:

σ_c = P / ( 2 a D_p )

Related:

• Truck and Car Universal Joint Design and Engineering Equation
• Universal Joint Maximum Minimum Speed | Engineering Reference and Online Tools

Reference:

Mechanical Engineering Data Handbook, James Carvill, 2003