The Process of Static Balancing

  Marvel manufactures a series of balancing arbors that are designed to balance loads ranging from one pound to 3,500 pounds. Each of these arbors can be used for multiple applications merely by changing balancing adapters.
  Two types of adapters are available: Thru-Shaft Mounting and Under Slung Mounting. Thru-Shaft Mounting will accommodate thru-shaft and splined propellers and thru-shaft main and tail rotor assemblies. Under slung mounting will accommodate flange mounted propellers and those rotor assemblies whose design does not permit thru-shaft mounting
  The balancing arbor is a vertically suspended device upon which a load to be balanced is horizontally mounted. The arbor features an extremely high degree of sensitivity and accuracy. Its design virtually eliminates internal wear surfaces and internal frictional resistance. Therefore, there is no requirement for the replacement of worn parts - only routine reconditioning and inspection.
  The characteristic response of the suspended balancing arbor to a load in a state of imbalance is a tilting action. This action occurs through an internal flexible solid suspension element located at a predetermined point on the arbor suspension rod. This suspension rod is encased in an oil filled shaft. This oil filled reservoir provides a dash-pot for dampening excessive oscillation of the sensitive balancing mechanism. The degree of oscillation dampening is regulated by raising or lowering the oil level in the reservoir or by varying the viscosity of the oil used.
  The arbor is free to tilt about the suspension rod to the extent necessary to indicate direction and relative magnitude of the unbalancing forces in the load. This displacement is observed as an eccentricity between an indicator bushing and a black indicator disc.