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Cylinder-driven clamp arm animation | Stroke, jaw clearance and contact
Compare rear-body and rod-side body pivots on a cylinder-driven clamp arm. See full stroke and current rod extension, edit geometry and speed, and inspect contact or a stroke shortfall.
The blue cylinder extends and raises rear pin B. The arm turns around fixed pivot O and its opposite end closes on the part. Retraction opens it. Arm angle comes from the actual pin distance rather than an arbitrary angular animation. A is the fixed cylinder-body pivot, B is the rod-end eye, and O is the arm pivot. The initial example also changes mounting height b to compare two installations.
- ① Play the clamping motionExtend → close the arm → contact the part → retract and open.
- ② Choose pivot mount, geometry and full strokeSwitch between rear-body and rod-side body pivots. Distinguish full available stroke S from the current extension e.
- ③ Check clearance and contactA candidate with insufficient extension stops short and its result turns red.
Compare the motion
A preset replaces both A and B. Edit blue fields individually. Numerical inputs are not saved.
B: comparison
Height gap g above the work surface
A: reference
Speed, angle and time
B: comparison
Speed, angle and time
Compare your own inputs
Each field shows its input range. Editing pauses playback and returns to the starting pose.
A: dimensions and inputs
B: dimensions and inputs
Equations and scope
Relative to pivot O, base pin A=(−a,−b) and rod pin B=(−a cosθ,−a sinθ). Pin distance satisfies ℓ² = 2a²+b²−2a²cosθ−2ab sinθ. Extend at the entered constant cylinder speed and solve θ from ℓ. Contact is placed at θ=0°, so required extension is b−ℓ₀. Stop at contact or the available extension S, hold 0.5 s, then retract.
What this motion model covers
Ideal planar rigid-body motion with pin joints, on the branch where extension closes the arm without crossing a dead centre. The drawn pad is 18 mm below the arm centre and 12 mm wide; the workpiece is 32 mm wide. Its upper surface is placed at contact when θ=0°. The cylinder outline is generic and not a product drawing. Verify real retracted pin spacing, mounting dimensions, stroke, clearance, pressure, thrust, holding force, losses and deformation separately. Contact is not a holding-force or safety approval. The open pose is the fully retracted position e=0. This drawing uses body length S + 20 mm, width 18 mm and at least 10 mm of exposed rod at retraction. These allowances are drawing geometry, not universal cylinder design rules. A rear mount requires S ≤ ℓ₀ − 30 mm. At a rod-side pivot the body extends behind A. Identical A/B positions give identical arm motion for either mount; body placement changes. Check actual product length, rod length and interference separately.
The viewing window is at most 600 seconds. Fast rotation can appear stationary through sampling. Reduce the playback multiplier to inspect it.
Values are not transferred automatically to calculators. Check the required conditions before entering them.
Common questions
How is this different from a swing clamp?
Here the cylinder drives a separate arm around a fixed pivot to clamp against a support. A swing clamp rotates its arm around the rod axis before moving straight down.
What changes with arm length?
A farther contact point has greater opening height and travel speed for the same arm angle. Required cylinder extension is set by rear arm a, cylinder mounting and opening angle.
What does insufficient stroke mean?
The extension required from the open pose to contact exceeds available extension S. The animation stops with a remaining gap.
Does contact prove adequate holding force?
No. Actual force depends on cylinder thrust, mechanical advantage, losses and the applied load. Check pressure and product specifications separately.
How does full stroke differ from current extension?
S is the available travel from the fully retracted position. e is how much of it has been used now. Both appear beside the moving diagram and in the results. Contact can stop extension before e reaches S.
Does changing the body pivot change arm motion?
The body sits behind or ahead of the fixed pivot according to its mount. Identical A/B coordinates give identical arm motion. Changing mounting height b or other geometry changes required stroke and timing.
Explore more motion
Inspect force transmission and drive effort
Clamp force follows cylinder thrust and moment arms about the arm pivot. Actual clamp force is zero before contact. The model applies the vertical load resultant at the pad centre.
Load calculations exclude friction, inertia, deformation and part strength except explicitly entered cylinder losses or screw efficiency. Capacity comparisons cover only the entered condition, not overall machine safety.