# Types Of Constrained Motion: Definition With Examples

In kinematics, when two parts are connected so that it offers relative motion, it is called kinematics pair. And when two body is constrained in such a way that it offers relative motion in at least one direction, it is called constrained motion. We will learn more about constraint motion and the types of constrained motion in this article.

## What is constrained motion?

We all know that there are six degrees of freedom when a body is not constrained. When we lock all degrees of freedom, there will be no motion in any direction.

Constrained motion philosophy occurs when the body is constrained in all directions but is free to move at least in one direction. That motion is called constrained motion.

But keep in mind that constrained motion does not mean that the body is fully constrained because if the body is fully constrained, then there will be no motion at all.

## Types of Constrained Motion

There are three types of Constrained Motion

• Completely constrained motion
• Partially or successfully constrained motion
• Incompletely constrained motion

## Completely constrained motion

When two bodies are constrained so that it allows motion only in one direction without bothering about at what direction the force is applied, it is called completely constrained motion.

For example, a rectangular shaft in a rectangular hole can move only in one direction, and there will be no rotation. The shaft can move only in the X direction in the above picture, but it can not rotate. Please note that even if the part has motion in a positive or negative direction, it will be called a completely Constrained motion.

## Partially or Successfully Constrained Motion

Partially or successfully constrained motion can have motion in more than one direction without any external forces. But when external forces are applied, it can have motion only in one direction. That is why it is called a partially constrained motion or successfully constrained motion.

For example, a footstep bearing needs external forces to be applied first to motion only in one direction. Engine valve motion is also a partially constrained motion.

## Incompletely Constrained Motion

If part can move in more than one direction in a kinematic pair, then it is called incompletely constrained motion.

For example, a circular shaft in a circular hole can move in two directions. One is the sliding motion, and the other is rotational motion.

## Conclusion

That’s all I have in this article. I hope you got a fair idea about different types of constraint motion in this article. If you still have any questions or queries, you are always welcome to write in the comment section, and I will be more than happy to reply to you back.

You may also like to read: What Is a free body diagram

## Frequently Asked Questions On Types Of Constrained Motion ( FAQ)

### What Is Constrained Motion?

When two parts are constrained and create a kinematic pair but still offer motion in one or more than one direction then it is called constrained motion.

### What are the types of Constrained Motion?

There are three types of constrained motion.
Completely Constrained Motion
Partially Constrained Motion or Successfully Constrained Motion
Incompletely Constrained Motion

Rajib

A 2004 batch Mechanical Engineering graduate From NIT, Agartala. Close to 16 years of experience in the field of consumer electronics and appliances domain as a Sr. Design Engineer and Team Leader in India and the United States. A GD&T practitioner, with expertise in Lean Manufacturing and Six Sigma. Crazy about exploring CAD-CAM tools and in his free time love to go for a ride with his champ, Rian.