Four bar Mechanism (Grublers Criterion)PPT.pptx

Subject Name: Kinematics and Theory of Machine

1. A PRESENTATION ON GRASHOF’S LAW BY IRFAN ALI ROLL- 35000721031 PC-ME503 Kinematics and Theory of Machines 3 RD YEAR MECHANICAL ENGINEERING Semester: 5th Ramkrishna mahato government engineering college,purulia

2. Grashof’s Law The Grashof’s law states that for a four-bar linkage system, the sum of the shortest and longest link of a planar quadrilateral linkage is less than or equal to the sum of the remaining two links, then the shortest link can rotate fully with respect to a neighboring link. Consider a four-bar-linkage. Denote the smallest link by S, the longest link by L and the & other two links by P and Q. If the Grashof’s Law condition is satisfied i.e S+L ≤ P+Q, then depending on whether shortest link ‘S’ is connected to the ground by one end, two ends, or no end there are 3 possible mechanisms. They are: 1.Double crank mechanism 2.Double-rocker mechanism and 3.Crank and Rocker Mechanism

3. 1. Double crank mechanism It is also known as the crank mechanism or drag link mechanism. In the double crank mechanism, the shortest link that is s is fixed or grounded. In this mechanism, both links on a fixed link can rotate 360 degrees.

4. 2. Double Rocker Mechanism In a double rocker mechanism, the link is fixed or grounded as opposed to the shortest link. In this system, the shortest link can rotate 360 degrees. The shortest link is called a coupler. Both links given to a fixed link can oscillate. These two links are called rockers.

5. 3. Crank and Rocker Mechanism In the crank and rocker mechanisms, the link adjacent to the shortest link is fixed or grounded. In this system, the shortest link rotates, and the second link is caught by fixed link oscillations.

6. Length of Any Two Link Are Same If the length of any two links is the same, then the length of the remaining two links will also be the same due to the equation S + L < P + Q. In such a case, two links are possible depending on the placement of the link: – Parallelogram Linkage :- In this linkage, links of equal length are placed opposite to each other. Deltoid linkage :- In this linkage, links of equal length are placed adjacent to each other.

7. THANK YOU BY IRFAN ALI 3 RD YEAR MECHANICAL ENGINEERING