Abstract:

ESDU 90007 gives methods for partially balancing single-degree-of-freedom multi-bar linkages by adding counterweights rotating at constant speed. The methods are (a) Lanchester Balancer using two equal counter rotating weights sized and aligned to eliminate a single frequency term of the frame shaking force, (b) a single weight sized and aligned to minimise the average shaking force, (c) Generalised Lanchester Balancer using two unequal counter rotating weights sized and aligned to eliminate a single frequency term of both the frame shaking force and moment, and (d) a moment balancer using two equal weights rotating in the same direction and sized and aligned to eliminate only the first-order frequency of the frame shaking moment. The mass-moment and orientation of each counterweight are determined by a step-by-step procedure that, in the case of the Generalised Lanchester Balancer, also provides the location for the axis for the second counterweight. Worked examples show the practical use of the procedures in the design of a crank-rocker linkage and in retrofitting a slider-crank mechanism. A computer program of the method is provided as ESDUpac A9007.