This page now separates a connected qualitative OHV pushrod train from a deliberately limited ideal-column calculation. The calculator reports section properties and Euler elastic buckling for declared geometry and end factor; it does not rate an engine pushrod or valvetrain.
Ideal Hollow-Column Buckling Screen
Enter declared free length, outer diameter, wall thickness, Young's modulus and effective-length factor. The results apply only to an ideal straight prismatic elastic column.
Equation Used
- The declared tube is straight, prismatic, homogeneous and linearly elastic.
- Input ranges keep inner diameter positive: Di=Do-2t.
- Load is perfectly axial and the declared K represents ideal end restraint.
- Euler theory is applicable only in the long-column elastic regime; the page does not decide applicability.
- The connected valvetrain animation is qualitative and is not dimensioned from the calculator inputs.
- Yield, local shell buckling, imperfections, residual stress, end-seat contact, bending, surge, inertia, fatigue, temperature, wear, ratings, selection and safe operation are excluded.
Removes the unsupported 40% safe-load claim and clearly separates an ideal Euler hollow-column screen from the qualitative OHV pushrod mechanism.
A pushrod transmits follower motion to a rocker
The qualitative animation connects a cam follower to a fixed-length pushrod and rocker, then shows the opposite rocker tip moving the valve. It is a topology illustration, not a dimensioned engine model.
The calculator is separate: it treats the entered tube as an ideal axially loaded column and does not calculate valvetrain motion or force.
Use only as an ideal-column screen
The worksheet reports hollow-tube area, second moment, radius-based slenderness and Euler load for declared values.
It cannot select or rate a pushrod, spring, cam, rocker or engine.
Ideal hollow section and Euler relation
Euler load is an ideal elastic instability result, not an allowable or safe load.
A transparent ideal-column example
With L=7.4 in, Do=0.3125 in, t=0.08 in, E=29 Mpsi and K=1, the calculator evaluates the declared hollow section and ideal Euler load. No 40% safe-load claim is retained.
Real pushrods are not perfect Euler columns
Actual behavior can be governed by material yield, local deformation, initial curvature, end-seat contact, bending, valvetrain inertia, spring surge and fatigue. Those require component drawings, material data and dynamic loads.
The former universal safe-load factor and unsupported engine performance, material, tolerance, failure, selection and troubleshooting claims are removed.
Ideal pushrod-screen questions
Is Euler load an allowable load?
No.
Does the calculator include valve-spring force?
No.
Does it check yielding or fatigue?
No.
Is the animation dimensioned from the inputs?
No; it shows topology only.
Ideal-column references
- MIT OpenCourseWare, Structural Mechanics Lecture 10: ideal prismatic-column buckling scope.
- Purdue ME 323, tubular-column buckling example: effective length and radius-of-gyration workflow.
- NIST Technical Note 1842: Euler load, KL effective length and slenderness notation in column-strength context.
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