Another example of a common linkage with a branch defect is the slider-crank link-age (crankshaft, connecting rod, piston) used in every piston engine and shown in Figure 13-3 (p. 601). This linkage has two toggle positions (top and bottom dead center) giving it two branches within one revolution of its crank. It works nevertheless because it is carried through these stationary configurations by the angular momentum of the rotating crank and its attached flywheel. One penalty is that the engine must be spun to start it in order to build sufficient momentum to carry it through these toggle positions.