﻿ General Design Information > Basic Kinematics > Kinematic-Chains in MECHDESIGNER > Motion-Parts and Motion-Points

# Motion-Parts and Motion-Points

#### Motion-Parts and Motion-Points

Comparisons between the Motion-Part and Motion-Point

 Motion-Parts are: •Parts that have their motion specified by a Motion-Dimension FB •A Joint constraint the Part to either Rotate or SlideMotion-Points are: •Points that have their motion specified by a Motion-Path FB•A sketch-element constraints the Point to slide along its length Motion-Point < > Motion-Part Constrained by a Sketch-Element < > Constrained by a Joint Motion-Path FB < > Motion-Dimension FB

#### Motion-Parts

 Motion Dimension FB A Motion Dimension FB: •identifies a Part - that becomes a Motion-Part - we want to move with a specified motion•specifies the position of the Part relative to a different Part Rocker A Rocker is a Part joined to a kinematically-defined Part with a Pin-Joint with a Motion Dimension FB to define its rotational angle between Lines in the two Parts that radiate from the Pin-Joint. Slider A Slider is a Part joined to a kinematically-defined Part with a Slide-Joint, that uses a Motion Dimension Function-Block to define the directional distance between Points at the end of the Lines used to define the Slide-Joint.

#### Motion-Points

 Motion-Path FB A Motion-Path FB is similar to a Motion-Dimension. A Motion-Path FB •adds a Motion-Point to a sketch-element and identifies it as the Point we want to move with a specified motion•specifies the position of the Motion-Point along the sketch-element or sketch-loop There are many application that can use a Motion-Path FB.  However, there are two useful 'Motion-Dyads'. See Tutorial 16. •Ram-R The Ram-R is a similar to an R-R-R Dyad, but one of the Parts extends. The Ram-R makes use of the Motion-Path FB. The Motion-Path FB adds a Motion-Point to a sketch-element (CAD-Line) in one Part. The other Part is joined to the Motion-Point with a Pin-Joint. motion-values are given to the Motion-Path FB by Motion FB. The Red Arrow in the image shows the Motion-Path of the Motion-Point along the CAD-Line of one of the Parts. •Ram-P The Ram-P is a similar to an R-R-P Dyad, but one of the Parts extends. The Ram-P makes use of the Motion-Path FB. The Motion-Path FB adds a Motion-Point to a sketch-element (CAD-Line) in one Part. The other Part is joined to the Motion-Point with a Pin-Joint. motion-values are given to the Motion-Path FB by Motion FB. The Red Arrow in the image shows the Motion-Path of a Point along the CAD-Line of one of the Parts.

#### Rocker

The Part is a 'Free' Part.

The Part has three Degrees-of-Freedom

2.Add a Pin-Joint between two Points

The Pin-Joint removes two Degrees-of-Freedom.

The Part now has one Degree-of-Freedom

The Part has Zero (0) Mobility. Notice the Part-Outline and Pin-Joint are green

 'Expand' then 'Play'

See Video to the Left.

#### Kinematics-Tree

The elements that define a Rocker are:

Pin-Joint

Part

Mot-Dim Rocker