<< Click to Display Table of Contents >> Navigation: Getting Started Tutorials - MechDesigner > Tutorial 10: Model Mechanical Devices > Step 10.3: The Oldham Coupling |
The Oldham Coupling transmits power between shafts that are parallel and offset from each other. A floating disc, in the middle of the coupling, has a raised rib on each face. Each rib is perpendicular(⊥) to each other. The raised ribs engage with slots in flanges on the input and output shafts. The Oldham Coupling is a kinematically-defined chain that is built with a: 1.Motion-Part, and 2.PPR Dyad |
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The video shows an Oldham Coupling. Input The Input Crank – the Motion-Part Output The Output Crank – rotates at the same constant speed. Middle Disk This transmits power/torque from the Input to the Output Crank. |
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A kinematic-chain has a Motion-Part. as an input. STEP 1.Add the Motion-Part – a Crank 1.Edit the Base-Part : Geometry toolbar > Add Line : Drag to add the Line Add Horizontal Constraints, Add Dimensions, Close the Part-Editor 2.Mechanism-Editor: Click Kinematic elements- > Add Part : drag to add the new Part. 3.Mechanism-Editor: Click Kinematic elements- > Add Pin-Joint: Click the start-Point of the new Part and the start-Point of the Line in the Base-Part. 4.Mechanism-Editor: Click Kinematic FB toolbar > Add Motion-Dimension FB: Click the Pin-Joint the Line in Base-Part; the CAD-Line in Part. and 5.Mechanism-Editor: Click Kinematic FB toolbar > Add Linear-Motion FB: and click the Graphic-area. Joint the FBs with a wire. You have a Crank |
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We now want to add a Dyad. Dyads ALWAYS have two Parts and three Joints. Never forget this! STEP 2.Add the Dyad Dyad: Part-2 and Joint-3 The output of the Oldham Coupling rotates. 1.Mechanism-Editor: Click Kinematic elements- > Add Part 2.Mechanism-Editor: Click Kinematic elements- > Add Pin-Joint |
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Dyad: Part-1 and Joint-1 1.Mechanism-Editor: Click Kinematic elements- > Add Part 2.Mechanism-Editor: Click Kinematic elements- > Add Slide-Joint a.Click the CAD-Line in the Part b.Click the CAD-Line along the Crank |
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Preparation for the middle Joint - Joint 2 1.Edit Part 2.Close the Part-Editor Note: The +X-axis is the direction you drag to the add the Line. - from its start-Point to its end-Point. |
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Dyad: Joint 2 1.Mechanism-Editor: Click Kinematic elements- > Add Slide-Joint a.Click Line b.Click CAD-Line
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The Oldham Coupling is Complete. You can add Extrusions to the Parts to show the coupling as a Solid model.
Note: Part-1 (the Output-Part) may be 180º to the direction it is in this image. The direction of the +X-axis of the Output-Part is the same direction Line (start-Point to the end-Point) you add to make the Slide-Joint. The +X-axis of a Line is the same as the direction you drag your mouse-pointer to add the Line. |
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The Kinematics-Tree shows the Motion-Part - Rocker (Crank) and the new R-R-P Dyad. Note: this is the same Dyad as the Scotch Yoke! Oldham Coupling, you connect the R Joint to the Base-Part and the P-P Joints are internal to the kinematic-chain. Scotch-Yoke, you connect the P Joint to the Base-Part, and the R-P Joints are internal to the mechanism. |