Mechanical Advantage of a four bar linkage.

In summary, the conversation is about a project involving a four bar linkage and the use of a torsion spring and servo to fling the linkage forwards. The person is looking for equations to calculate the transfer of torque and force between the legs, as well as advice on selecting a powerful enough servo. They mention that the front leg will likely be longer than the back leg and that the top and bottom legs are of equal length. They are advised to start with kinematics and use the method of virtual work to determine the mechanical advantage. The person is also asked if they have a Theory of Machines textbook.
  • #1
racast5
2
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I'm doing a project outside of school and I need some help with the mechanical advantage of a four bar linkage. Ideally I want to have a torsion spring attached to the frontward most arm so that I can load the linkage and have it fling forwards. I want to use a servo to load the spring which i was going to attach to the backmost leg. Can someone point me in the right direction where I can find some equations for the transfer of torque/force between the legs? Ideally I want to put something like a 20-30 lb/in torque spring on the front end and so I need a servo powerful enough to load it. The case will likely be that the front leg is longer than the back leg while the top and bottom legs are roughly equal in length. I'm just getting started on this so sorry if it's a little not thought out but I was looking for some pointers.
 
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  • #2
So, where is your analysis of the four bar mechanism? You need to start with the kinematics, and then you can easily use the method of virtual work to get the mechanical advantage. Show me what you have when you get that much done, and we can go from there.

Do you have a Theory of Machines textbook? Which one?
 

1. What is a four bar linkage?

A four bar linkage is a mechanical system made up of four rigid bars connected by joints or pivot points. It is commonly used in machines to convert rotational motion into linear motion or vice versa.

2. How does a four bar linkage work?

A four bar linkage works by using the principles of kinematics and mechanics to transmit and transform motion between the input and output links. The input link is typically rotated, causing the other three links to move in a coordinated manner.

3. What is the mechanical advantage of a four bar linkage?

The mechanical advantage of a four bar linkage refers to the ratio of the output force to the input force. It is influenced by the lengths and positions of the four bars, as well as the orientation of the input and output links. A longer input link and shorter output link will result in a higher mechanical advantage.

4. What are the applications of a four bar linkage?

A four bar linkage has many applications in various industries, including automotive, aerospace, and robotics. It is commonly used in mechanisms such as car suspension systems, windshield wipers, and robotic arms.

5. How can the mechanical advantage of a four bar linkage be improved?

The mechanical advantage of a four bar linkage can be improved by adjusting the lengths and positions of the four bars, as well as the angle of the input and output links. Additionally, using different types of joints or adding additional links can also increase the mechanical advantage.

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