The lengths of the links comply with the conditions: A͞B=D͞C, A͞D=B͞C=E͞F, A͞E=D͞F and B͞E= C͞F. Thus the basic mechanism of the scales is parallel-crank linkage ABCD. Platform 1 has translational motion. Rigidly secured to link 2 is hand a which indicates the weight being weighed on scale b. Weights c counterbalance the weight of platform 1 and the links of the mechanism.
$792$LW,B$