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Four-bar linkage step by step
From a blank sheet to a fully rotating four-bar linkage with bearing forces and friction – the whole process in ASOMmini.
Example · Basics · ASOMmini
Approximate straight-line linkage by Chebyshev
How straight is the path of the Chebyshev straight-line linkage really? In ASOMmini, you build the four-bar linkage and read off the deviation directly.
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The task
How straight is the path?
A straight-line linkage turns a rotary motion into a straight-line motion; the simplest solution is a four-bar linkage. In Chebyshev's design, frame, rockers and coupler have a length ratio of 4 : 5 : 2. However, the path of coupler point P is only approximately straight – how accurate it is remains to be seen.
What ASOMmini shows here
- The four-bar linkage is built from links and joints; you enter the joint positions numerically in the properties.
- The animation draws the path of P as a trajectory, and a diagram shows its position over time – the Y coordinate tells you how straight the path is.
- With a coupler length of 20 cm, the straight section lies within a corridor about 1 mm wide.
Your benefits
Check accuracy before anything is built
You see not only that the mechanism guides in a straight line, but also how accurately – and recognize early on whether the solution is good enough.
Numbers instead of judging by eye
You assess the straight-line linkage based on values from the diagram, not by eye. More on analysis
Weigh the variants
In a variant with a ratio of 5 : 6.5 : 2 and the same coupler length, the corridor becomes narrower than 0.2 mm, but the straight section is about 11% shorter.
Forces as well
Optionally, ASOMmini also calculates bearing forces and friction for the same straight-line linkage. More on force calculation
More examples
All example videos
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Roller follower
A roller follower couples a four-bar linkage and a one-bar linkage. The cam curve follows every change immediately and can be exported as a list of points.
1:25
Four-bar linkage with manual force
The manual force element shows in real time how the required manual force changes when you move the application point, a bearing or the center of gravity.
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