dead-centres
The angles this crank cannot reach
A non-Grashof four-bar — non-Grashof (triple rocker) — asked for all 360 input angles. It assembled at 273 of them. The dial on the left marks the reachable arcs in green and the refused ones in red; the refusals are not a numerical failure but the mechanism's dead centres, where the crank and coupler line up and the linkage physically stops. Nothing about the four lengths had to be inspected to find them: the solver was asked, and declined.
Where it is used
- What decides whether it moves What can move
- Counting and measuring mobility What can move
- Grashof, predicted and then swept Linkages
- Two things called jamming Drawn wrongly
- The mechanism Grübler says cannot move What can move
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