1. The grashof condition(曲柄存在条件) It is used to predict the rotation behavior or rotatability of a four-bar linkage's inversions based only on the link lengths g/ A D Two key positions1.The Grashof condition(曲柄存在条件) It is used to predict the rotation behavior or rotatability of a four-bar linkage’s inversions based only on the link lengths. Two key positions