Transversely loaded pin shear stress

What does this quantity describe?

A clevis pin usually sits in double shear between a fork and an in-between rod. Transverse force F then splits across two shear planes; mean shear stress follows from τs = F/(m·A), with A = π·d²/4 the pin cross-section and m the number of shear planes.

Picture a bolt cutter distributing the same load across one or two blades: with two blades instead of one, each blade carries only half the force, halving stress per blade.

Formula and variables

τs = F / (m · π·d²/4)

• τs = F/(m·π·d²/4)
• F = τs·m·π·d²/4
• d = √(4F/(τs·m·π))

Choose the inputs correctly

Transverse force F, pin diameter d and shear planes m (1 for single shear, 2 for double shear) set the mean shear stress.

How to use the calculator

Enter force, diameter and shear configuration to check shear stress. For a sizing question — what diameter an allowable stress needs — use the linked required-pin-diameter calculator.

Worked example

5,000 N on a double-shear pin with a 16 mm diameter give τs = 5,000 N / (2 · 201.1 mm²) ≈ 12.4 MPa.

Understand the result and units

A shear stress of 12.4 MPa is far below typical allowable values of roughly 50 to 100 MPa for pin steels; using single shear instead of double shear at otherwise equal values would double the stress to about 24.9 MPa.

Force is given in N, diameter in mm, and the resulting stress in MPa (N/mm²).

Why shear alone is rarely enough

A clevis pin is not purely sheared but carries load across distributed bearing zones at the fork and rod, additionally creating a bending moment. For short, thick pins with little distance between the bearing zones, shear stress usually dominates; for slender pins with more distance or clearance, bending stress can markedly exceed shear stress and govern the design. A complete clevis pin check therefore always covers shear, bending and bearing together.

Typical applications

The calculation is used to check and pre-size clevis pins, piston pins and pin joints in machine and vehicle engineering, particularly for fork joints on cylinders, links and levers.

Assumptions, limits and common mistakes

This pure nominal stress considers only the external force. Press-fit preload, local notch stress at transitions and, above all, the additional bending a clevis pin experiences are not included here and must be checked separately with the clevis pin bending calculator.

Common mistake: A common mistake is checking a clevis pin for shear alone and overlooking the often more critical bending stress. Shear plane count is also sometimes set incorrectly, for example in an arrangement with a through-pin lacking a true second shear plane.