<< Click to Display Table of Contents >> Navigation: Getting Started Tutorials - MechDesigner > Tutorial 2A: Four-bar Kinematic-Chains > Step 2.7: Reconfigure to a 6-bar Whitworth Quick Return |
You are going to design a 'Whitworth Quick-Return Mechanism'.
Why not start a new mechanism on a new Plane?
See also this link: http://youtu.be/MrvAKlePm3k?t=11s
A kinematic-chain may have:
•One, or more, Motion-Parts
•One, or more, Dyads
Notice 'or more' in the new definition of a kinematic-chain. This is because it is easy to add Dyads and to add more than one Motion-Part to a kinematic-chain.
A Whitworth Kinematic-Chain:
•One Motion-Part
•Two dyads
Remember, ALL Dyads have:
•Two Parts
•Three Joints
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 •Three Joints: a RPR Dyad otwo Pin-Joints: join the long Part to the Base-Part oone Slide-Joint |
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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 •Pin-Joint Join the Parts together. •Slide-Joint 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: •the Parts are joined to two other Parts oPart oThe Base-Part •the Parts are also joined together. Now you do it....Add the first and last joints of the Dyad: •Pin-Joint •Slide-Joint •Pin-Joint 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? |