Make the Motion-Part a Slider and not a Rocker

In this Tutorial:

Video 1:

1.We delete the Pin-Joint at Sliding-Part, and add a new Pin-Joint to the other end of the Sliding-Part
2.We change the Dyad Closure of the RRP

Video 2:

3.Move the Motion-Dimension FB to the Slide-Joint. The input becomes a Slider.

Typically, the name of the new mechanism is a 'Slider-Crank'.

4.We will look at the Kinematics Tree again.



tog_minusVideo 1: Move Pin-Joint and Change Dyad Closure [with Right-Click short-cut]

Tutorial 2; Step 2.5.1





'Right-Click Short-Cut'

to change Dyad Closure
tog_minusVideo 2: Change from Crank-Slider to Slider-Crank

Tutorial 2; Step 2.5.2


Motion-Dimension Rocker


Motion-Dimension ... a Slide-Joint ... make a Slider


Step by Step...

tog_minusEdit the Pin-Joint on the Sliding-Part.

We want to move the Pin-Joint to the different end of the Sliding-Part.

We must delete the Pin-Joint, then add a new Pin-Joint, again.

There are many ways to delete an element.

In this step we will practice using the contextual-menu with 'Hover-above-element + Right-Click' , and then click Delete Element


Do 1 and 2.

1.'Hover + Right-Click'  above the Pin-Joint

You must make sure ONLY the Pin-Joint is hovered [and RED] and not more elements.

If more than one element becomes RED, a different contextual-menu will show.

The text is very light, you may have difficulty seeing the text in the contextual-menu [to be improved soon]

2.Click 'Delete' in the contextual-menu [the menu is not easy to see!]


When the Pin-Joint is deleted...

D 3, 4, and 5

3.Drag the Parts to a different Place
4.Click Kinematic elements toolbar > Add Pin-Joint
5.Click the two Points.


If the 'Closure' is the same as the image then we can change its closure.

There is a right-click short-cut.


To change a 'Dyad Closure' right-click short-cut:

1.Click Kinematic elements toolbar > Change Closure
2.Right-Click a Part in the RRP Dyad.

The right-click short-cut selects the element and also exits the Command-Manager successfully when all the selection-boxes are complete.

Do step 1 - 2 again and again until the Dyad is the same as the image.

Note: The 'right-click short-cut trick' applies when the Command-Manager has one selection-box'.

tog_minus        Move the Motion-Dimension FB from the Pin-Joint to the Slide-Joint

When the Motion-Dimension FB is at a Pin-Joint, we call the Motion-Part a Rocker.

Its 'positive' angular direction is always Counter-Clockwise [Anti-Clockwise].

When the Motion-Dimension FB is at a Slide-Joint, we call the Motion-Part as Slider.

Its 'positive' direction is more complicated.

You must think of the 'positive' directions of the two Lines that you click to add the Slide-Joint.


We must delete the Motion-Dimension FB at the Pin-Joint before we can add a new Motion-Dimension FB to the Slide-Joint.

The recommended method to delete an element is to:

STEP 1: Click the Motion-Dimension FB in the graphic-area.


SW-Delete- MotDim

The Motion-Dimension FB element will be in the Selection-Window

STEP 2: Right-click the Motion-Dimension FB in the Selection-Window
STEP 3: Click 'Delete' in the contextual-menu


Alternatively, you can click an element so that it becomes red, then use your delete key on your keyboard.


All of the Part-Outlines in the kinematic-chain should be Blue.

The kinematic-chain has one degree-of-freedom again.

Remember: Blue Part-Outlines are NOT kinematically-defined.


You can drag the Part-Outlines if you like. It is not easy, but you can!

[To Drag: hover above the Part-Outline to make it Red, then Drag.

In this case, it is easiest if you drag the Part-Outline of the Part that was the 'Rocker'.

Move the Parts to a position that is similar to that shown in the image to the left.

(IMPORTANT NOTE FOR SOME USERS: Occasionally, you can only hover to make a Part-Outline Red by hovering over the Part-Outline at the arcs, near the start and end Points, at each end of the Part)]


Now, we will add a new Motion-Dimension FB.

STEP 4: Click Kinematic FB toolbar > Add Motion-Dimension FB
Add menu > Add Motion-Dimension FB.


The Command-Manager shows you must select three elements from the graphic-area.

The top selection-box in the Command-Manager is the colour of dull pink 'English' skin, to show it is ready for you to select the element.

You do NOT need to click inside the selection-boxes.

Each time you select an element, the Command-Manager automatically advances to the next selection-box, ready for you to click the next element.

Only click in a selection-box if you want to clear [remove] the elements from the selection-boxes.


STEP 5: The First Element: Click the Slide-Joint symbol

The Slide-Joint symbol you must click is one of the two rectangles that are along the length of each Line that specifies the Slide-Joint.

Please look at the image carefully to see the symbol of the Slide-Joint.

When you click a Slide-Joint symbol as the first element, the second and third elements you must select are Points. The Points must be at the ends of the Lines that specify the Slide-Joint.


STEP 6: The Second Element: Click a Point at one end of the Line in the Base-Part

The first Point must be at one end of the Line in the Slide-Joint that is a kinematically-defined Part.

Here, it is the Point at the end of the Line that we added to the Base-Part.


The second Point is at one end of the Line in the Free-Part. A Free-Part has a Blue Part-Outline.

STEP 7: The Third Element: Click a Point at one end of the Line along the centre of the Added-Part


STEP 8: Click OK in the Command-Manager to complete the command.

[You can also 'Right-click in the graphic-area' to complete the command. At the same time, the contextual-menu will show]

The kinematic-chain is now kinematically-defined again. The Part-Outlines are Green.

The Part that was a Free-Part is now a kinematically-defined Part.


STEP 9: Connect a wire from the output-connector of the Motion FB to the new Motion-Dimension FB

A Motion-Dimension FB identifies the Part we will move with a specified motion.

Because the Part is a child to a Slide-Joint, it is a Slider.


STEP 10: Do Kinematic element toolbar > Change Dyad Closure

If the Closure is not correct

Do Kinematic-elements toolbar > Change Dyad Closure


Click OK-tiny-13-17 in the Command-Manager when the correct Part is in the selection-box


tog_minus        The Motion-Dimension and Slide-Joint in the graphic area


Slide-Joint BEFORE we add a Motion-Dimension FB

The Part we will move with a motion must have a Blue Part-Outline4s. This means the Part is NOT yet kinematically-defined.

We use a number of symbols to represent a Slide-Joint:

1s-red Wide Rectangular Box: that is along the Line of the moving* Part.

2s Narrow Rectangular Box: that is along the Line of the fixed* Part.

* Remember, the two Parts might move. Thus, this it is not a perfect rule. However, there is ALWAYS a Wide and a Narrow Rectangular Box.

3s Small Arrowhead: at the start of one Line that you select for the Slide-Joint.

The small arrowhead is the 'Positive Direction' of the Slide-Joint.


Slide-Joint AFTER we add a Motion-Dimension FB

The Part-Outline4s is now Green. This means the Part is now a kinematically-defined Part

The small arrowhead, and the Wide and Narrow Rectangles are Green.

The symbols for the Motion-Dimension include:

1s-red The Dimension

2s The Dimension Line and the Extension Lines

3s The Motion-Dimension FB

As motion-values increase, the Slider will move in the positive-direction, as indicated by the small arrowhead.

The Kinematics Tree

The Kinematics-Tree has changed in Tutorial 2.

It has changed from a:

Rocker and RRR Dyad (Step 2.1)

to a:

Rocker and RRP Dyad (Step 2.3)

to a:

Slider and RRR Dyad (This Step)


This kinematic-chain is a Slider and an RRR Dyad.

The Slider is one of the two Motion-Parts.

It has three elements:

c.Mot-Dim Slider – a Motion-Dimension FB for a Slider

The RRR Dyad is one of the five Planar Dyads.

The RRR Dyad has five elements:


Tutorial and Reference Help Files for MechDesigner and MotionDesigner 13.2 + © Machine, Mechanism, Motion and Cam Design Software by PSMotion Ltd