For an in-line slider-crank with L > r, stroke is 2r, rod ratio is L/r, and maximum connecting-rod obliquity is asin(r/L). Its tangent is a dimensionless geometric lateral-to-axial component ratio, not a load prediction.
Slider-Crank Proportions · Exact Geometry Envelope
Explore exact slider-crank stroke, rod ratio and maximum obliquity without implying an unsupported side load.
Equation Used
- Crank and connecting rod are rigid and L is greater than r.
- Slider axis passes through the crank center.
- Maximum rod angle follows the complete crank rotation.
- Dynamics, forces, friction, clearance, strength and ratings are excluded.
The former side-factor label is replaced by geometric tangent ratio because no axial load is supplied.
Exact proportion envelope
The animation preserves the selected rigid crank and rod lengths while the slider remains on-axis. Dead centers and maximum rod-obliquity guide rays make the selected geometry envelope visible.
What the calculator determines
Select crank radius and rod length. The calculator reports exact stroke, rod ratio, maximum rod angle and tan of that angle as a geometric component ratio.
In-line slider-crank proportions
stroke = 2r; rod ratio = L/r; αmax = asin(r/L); tanαmax = (r/L)/√(1 − (r/L)²).
Selected-input arithmetic
For r = 50 mm and L = 150 mm, stroke is 100 mm, rod ratio is 3:1, maximum obliquity is about 19.47° and its tangent is about 0.354.
Geometry, not loading
Actual side force requires piston or slider axial force and depends on pressure, inertia, friction and operating angle. The model excludes speed, acceleration, loads, bearings, clearance, balancing, stress, fatigue and ratings.
Questions
Is tanα a side-thrust force?
No. It is only a geometric force-component multiplier if a compatible frictionless axial-load model is separately supplied.
Does a larger L/r reduce maximum obliquity?
Yes.
References & Further Reading
- Wikipedia contributors. Slider-crank linkage. Wikipedia
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