First, we should look at the Motion-Part and the first Dyad.

•A Motion-Part – a Crank

•A Dyad

The Dyad is assembled with:

•Two Parts: one long and one short

•Three Joints: a RPR Dyad

otwo Pin-Joints: join the long Part to the Base-Part (frame); join the short Part to the Crank

oone Slide-Joint to join the long and the short Parts together

Which order do we add the Joints to add a new Dyad?

After you add the two Parts as Free Parts, it is frequently easiest to:

1.Add the outer Joints. They join the two new Parts to two existing Parts in the kinematic-chain that are kinematically-defined.

2.Join the two new Parts in the Dyad together – this makes the 'middle' Joint in the Dyad.

Now you do it....

Add the first and last joints of the Dyad:

•Pin-Joint between the long part and the Base-Part: R – –

•Pin-Joint between the short Part and the end of the Crank: R – R

Join the Parts together.

•Slide-Joint to join the two Parts together: RPR

Now - remember about Closures? See Change Closure of a Dyad if the Dyad is in a Closure you do not expect. Keep using the same Change-Closure tool until the Dyad is in the closure you need.

The image shows the second Dyad.

It is simple to add more Dyads, to make a more complex kinematic-chain.

In the image, the second Dyad has:

•two more Parts: and

•the Parts are joined to two other Parts

oPart - which is the Long Part of the first Dyad

oThe Base-Part

•the Parts are also joined together.

Now you do it....Add the first and last joints of the Dyad:

•Pin-Joint between the long part and one of the new Parts: R –x –x.

•Slide-Joint along the Base-Part: R –x–  P.

•Pin-Joint joining the two Parts together: R–R–P.

Your challenge is to complete this mechanism. and put each Dyad in the correct 'Closure'.

Why not start a new mechanism on a new Plane?