ABSTRACT
Figure 3.1a illustrates a planar four-bar mechanism. The four interconnected links in this mechanism are the crank (the driving link), coupler, follower, and ground.* A supplied input rotation to the crank link compels the motion of the coupler and follower links. Both the crank and follower links are connected to the ground link (or are grounded) and undergo pure rotation (as indicated by the arrows).† The planar four-bar mechanism is one of the most widely utilized kinematic chains in everyday devices (Figures 3.1b, c, and d) including locking pliers, folding chairs, and doorways.
Figure 3.2a illustrates a slider-crank mechanism. The four interconnected links in this mechanism are the crank (the driving link), coupler, slider, and ground. A supplied input rotation to the crank link compels the motion of the coupler and slider links. In this mechanism, the crank link undergoes pure rotation, the slider undergoes pure translation and the coupler undergoes complex motion. The slider-crank mechanism can be theoretically described as a planar four-bar mechanism having a follower link of infinite length (Figure 3.2b) [1]. The slider-crank mechanism is also among the most widely utilized kinematic chains in everyday applications. Among the many everyday applications for the slider-crank mechanism is the crankshaft-connecting rod-piston linkage: a fundamental subsystem of the internal combustion engine (Figure 3.3).
