# four bar linkage
Four Bar Mechanism | Grashof’s Criterion | Examples Of Four Bar Mechanism
Four bar Mechanism consists of 3 moving links and 1 ground link (also called a frame). There are 4 pin joints connected between those links. And from Gruebler’s Equation, it’s the mechanism with 1 degree of freedom (1DOF) which requires only 1 actuator to drive and control position of all linkages. The four-bar mechanism consists of the following components.
The link that connects to the driver or power source is called the input link. The other link connected to the fixed pivot is called the output link. The remaining moving link connected between input and output links is called the coupler. It couples the motion of the input link to the output link.
There are different configurations of lengths of the four-bar mechanism and it results in different movements of the mechanism. Grashof’s Criterion helps classifies into the following categories:
Double Crank — also called a drag link mechanism
Please watch: “Elliptical Outdoor Bicycle – low Run Effort Bicycle | Mechanical project”