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Toggle (knee-lever) press mechanism

How much force does a toggle press give? · Hardware · basis: Xem Studio drawing; classic mechanism (Brown No. 164)

Also called: toggle mechanism, knee lever, toggle press, toggle clamp mechanism, mecanismo de rodillera, mecanismo de joelheira, Kniehebel, genouillère mécanisme

Exact dimensions. True size, with no printing tolerance added.

sizes
3 in table

Notes

  • Two equal links in line with the output, bent slightly at the knee. A side force F at the knee gives an end force F / (2·tan θ), θ = each link's angle off the straight line.
  • At θ = 15° the gain is 1.87×; it rises without limit as the links straighten (θ → 0), which is why presses, clamps and stone crushers use it.
  • The stroke shrinks as the force grows: the end moves 2L(1 − cos θ) while straightening.
  • Parts (each has its own page): toggle-links-50, crosshead-8mm, crosshead-guide-8mm, pins-3mm. Brown's movement No. 164 shows it (1868).

Toggle (knee-lever) press mechanism size chart

parametervalue
link centres L50 mm
angle θ (drawn)15°
force gain at θ1.87×

Where the files are

Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.

Henry T. Brown (1868, public domain)Five Hundred and Seven Mechanical Movements — scan on archive.orgwebPublisher's page; dimensions are facts

Free files

★ Free files 1 parts. Generated by Xem Studio from the standard; threads are plain cylinders at major diameter. CC BY 4.0. index.json

toggle-press-mechanism-assemblyAssembled mechanism, all parts placed (STEP keeps each part separate)STEP · STL
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Plain text: sheet.txt · JSON: /api/geometry?object=toggle-press-mechanism

Toggle (knee-lever) press mechanism, isometric render of a generated part
Render of toggle-press-mechanism-assembly from the free STEP; not to scale.

Fits with

Toggle links, 50 mm centres (pair), isometric render of a generated part
Toggle links, 50 mm centres (pair)3 sizes★ 1 file
Crosshead Ø8 × 24 for a Ø3 piston rod, isometric render of a generated part
Crosshead Ø8 × 24 for a Ø3 piston rod4 sizes★ 1 file
Crosshead guide, Ø8 bore × 30, isometric render of a generated part
Crosshead guide, Ø8 bore × 305 sizes★ 1 file
Crank and wrist pins Ø3 × 12, 16, 19, 20 and 23, isometric render of a generated part
Crank and wrist pins Ø3 × 12, 16, 19, 20 and 235 sizes★ 5 files

Questions

How much force does a toggle press give?

Two equal links in line with the output, bent slightly at the knee. A side force F at the knee gives an end force F / (2·tan θ), θ = each link's angle off the straight line.