Dialog: Function-Block: Continuous Crank

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Dialog: Function-Block: Continuous Crank


See also Add Continuous-Crank

It is often the case, that the desired motion is applied to a Tool. The Tool is not driven directly. A different Part is driving the input to a mechanism. The motion and forces are transmitted through the mechanism from the driving Part to the Tool Part.

Most typically, especially with a Cam mechanism, the driving Part oscillates and it is a cam-follower that is moved by a cam.

There is also an option that the driving Part completely rotates with a non-uniform rotating speed. This is a special-case. To make sure this can happen, the driving Part must be exactly the correct length. This is one application of the Continuous-Crank FB.

When the Crank rotates continuously in one direction, its is usually driven by a servo-motor. However, it is also possible to drive it with a Cam.

Open Continuous-Crank FB dialog-box


Edit the Continuous-Crank FB:

1.Double-click the Continuous-Crank FB in the graphic-area

- or -

1.See How to Open a Dialog-Box  

The Continuous-Crank dialog-box is now open.

Continuous-Crank dialog-box


STEP 1: Select Crank Behavior and Direction

Crank Behavior

Rotate - the Part will rotate continuously.

Oscillate - the Part will oscillate by 180º (see also Note)

Crank Direction


othe selected Part will rotate in the Counter-Clockwise direction.


othe selected Part will rotate in a Clockwise direction


STEP 2: Activate the Not Selected box

Click in the box labeled Not Selected

The Box is now Orange

The box is now Selected

You can now select a Part.

The Part must have a Pin-Joint with the Base-Part.



STEP 3: Click a Part

Click a Part in the graphic-area or Assembly-Tree

The Part will immediately change its length so that it can rotate continuously, or oscillate by 180º.

STEP 4: Confirm the behavior is as expected  

Do Run toolbar > Cycle Continuously (ALT+C)

STEP 5: Edit Crank Behavior and Crank Direction, as required.

STEP 6: Click OK-tiny-11-15 to close the dialog-box.

Note: if the Part rotates by 180º, but in the incorrect closure then, do Change-Dyad Closure