How to use this calculator
- Enter joint load. Use the load carried by the pin.
- Enter pin geometry. Use pin diameter and shear-plane count.
- Enter lug geometry. Use the center eye thickness, fork lug thickness and bearing-center span.
- Set allowables. Enter shear, bearing and bending allowables with a safety factor.
- Read utilization. The highlighted value is the worst of the stress checks.
How it works
Pin shear uses the total pin area in the active shear planes:
tau = F / (n x pi x d^2 / 4)
Bearing stress uses the projected contact area, d x t.
The pin bending check treats the clevis pin as a short simply supported beam:
M = F x s / 4. The round pin section modulus is
pi x d^3 / 32, so sigma_b = M / S.
Worked example
Verified against the live calculator
A 10,000 N load on an 18 mm pin in double shear gives
shear stress 19.65 MPa. With a 24 mm bearing-center span,
pin moment is 60,000 N*mm.
Bending stress is 104.8 MPa. The center eye bearing stress is
55.56 MPa, fork lug bearing is 34.72 MPa, and the worst
utilization is 0.838 with the default safety factor.
Frequently asked questions
How do you calculate shear stress in a clevis pin?
Average pin shear stress is tau = F / (n*A), where F is joint load, n is the number of shear planes, and A = pi*d^2/4 is pin area.
How is clevis pin bending estimated?
This calculator uses a simple double-shear beam model: M = F*s/4, where s is the bearing-center span. Bending stress is sigma = M / (pi*d^3/32).
How do you calculate lug bearing stress?
Bearing stress uses projected area d*t. The center eye carries F, so p_eye = F/(d*t_eye). Each fork lug carries F/2, so p_fork = (F/2)/(d*t_fork).
Why can bending control before shear?
Pin shear area grows with d^2, but bending stress scales with moment divided by d^3 and depends strongly on the lug spacing. A small pin in a wide clevis can bend before it shears.
Does this check lug tear-out?
No. You still need lug net-section tension, shear tear-out, edge distance, pin-hole clearance, fatigue and retaining hardware checks.
Should I use single or double shear?
A typical clevis has two shear planes. A lap joint has one. Use the shear-plane input to match your joint, but the bending model is intended for a double-shear clevis.
Method & assumptions
- Average shear and average bearing stress checks.
- Pin bending uses a simplified central-load beam model over the bearing-center span.
- Fork bearing assumes two outside lugs share load equally.
- Lug tear-out, net-section tension, clearance, fatigue, shock, retaining hardware and code-specific resistance factors are not included.