Motion-Path: Ram-R and Ram-P
We can use the Motion-Path FB to build two new pseudo-dyads:
•Ram-R
•Ram-P
An application of the Ram-R dyad is to control the motion of a linear actuator that drives a scissor lift.
Kinematics of a Ram-R
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Ram-R
The Ram-R is a similar to an R-R-R dyad. In the Ram-R dyad, one of the two Parts can change its length.
The Ram-R uses the Motion-Path FB to add a Motion-Point to a sketch-element ( e.g. the CAD-Line along the X-axis of a Part ).
We join the other Part to the Motion-Point with a Pin-Joint.
We add a motion to the input of the Motion-Path FB to control the motion of the Motion-Point.
The Red Arrow is the path of the Motion-Point along the CAD-Line of one of the Parts.
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How to add a Ram-R
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STEP 1: Add two Parts and join with Pin-Joints to a Line in the Base-Part.
1.Edit the Base-Part |
2.Close the Part-Editor
3.Add two Parts
4.Edit the length of the Parts =100mm
5.Add Pin-Joints between the start-Points of each Part and the end-Points of Line |
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 Motion-Path FB |
STEP 2: Add a Motion-Path FB
1.Click
2.Click the  along the center of the Part (on the left in this case)
3.Click  in the Command-Manager. |
The default position of the Motion-Point is at the start-Point of the sketch-element you select - in this case the CAD-Line.
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 Motion-Path dialog-box |
STEP 3: Edit the start Position of the Motion-Point.
There are two Parts that you have joined to the Base-Part with Pin-Joints. You will add one more Pin-Joint (See STEP 4) to give three(3) Pin-Joints in a triangular structure. To be able to add the last Pin-Joint, we must move the Motion-Point away from the start-Point.
1.Edit the Motion-Path FB
In the Point Parameters separator
2.Edit Linear Offset = 40 mm
3.Close the dialog |
The Motion-Point is now 40 mm from the start-Point of the CAD-Line.
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STEP 4: Add Pin-Joint
1.Click
2.Click the end-Point of the Cad-Line and then the Motion-Point that is at 40 along the CAD-Line |
The Pin-Joint joins the two Parts. The Ram-R dyad is now defined.
The Parts are kinematically-defined.
You may need to change the closure of the Ram-R dyad.
STEP 5: Change Dyad Closure
1.
2.Click the Part-Outline of one of the two Parts.
3.Click  in the Command-Manager |
STEP 6: Add a Linear Motion FB and a Motion FB
STEP 7: Edit the Motion FB and Data-Type
When you connect a Motion FB to a Motion-Path FB, you MUST edit the Output Data-Type to Linear or Rotary (the Data-Type should NOT be Motion).
1.Edit the Motion FB to open the Motion FB dialog
In the Motion FB dialog:
2.Enable Linear as the Output Data-Type
Close the dialog.
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STEP 8: Edit the Motion in MotionDesigner
The maximum displacement is 50.
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STEP 9: Connect the Linear-Motion FB to the Motion-FB to the Motion-Path FB |
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Add a 2D-Cam
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STEP 1: Add the Follower-Roller
1.Edit Part  to constrain the center of the circle to the end-Point of the CAD-Line. Exit Part-Editor.
2.Do
3.Click the circle
4.Click in the Command-Manager. |
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STEP 2: Add the Cam-Part
1.Add a Part and join it with a Pin-Joint* at the left of the Line in the Base-Part.
2.Add Motion-Dimension FB - so that Part is a Motion-Part (Rocker).
3.Connect a Linear-Motion FB to the input of the Motion-Dimension FB.
4.Edit the Motion-Dimension FB > Base-value = 0.
Part is the horizontal Cam-Part.
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* The Select-Elements dialog opens. CTRL + CLICK the start-Point of the Part and the start-Point of the Line in the Base-Part.
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STEP 3: Add the 2D-Cam
1.Do
2.Click the new Part as the Cam-Part.
3.Click the Profile as the Follower-Profile |
The 2D-Cam is now in the graphics-area.
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Kinematics-Tree
We call this kinematic-chain the Ram-R dyad
Kinematic-Chain #1 : The R-R-R is the Ram-R dyad - normally, this would be a structure. But a motion controls the length of one of the Parts in the dyad.
Kinematic-Chain #2 :The Rocker represents the Cam-Shaft.
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