Abstract: A vertical, hard suspension, two plane balancing machine has a suspension cartridge which drops into an aperture in a support plate of the machine base, and a spindle cartridge which slides snugly into bores in the suspension cartridge. The suspension cartridge has two vertically spaced and rigidly interconnected plates, each plate having a bore for the spindle cartridge and having a pair of arcuate slots concentric with the bore defining between the slot ends a pair of resilient webs comprising the machine flexure elements located diametrically on each side of the bore. A force transducer is located in a slot of each plate to measure vibration. The spindle cartridge has a rigid tube containing vertically spaced bearings which rotatably support the spindle. A motor coupled to the spindle through a belt drive is located in the same plane as the webs to minimize the effects of the belt drive forces on the force transducer.

Abstract: The present invention provides a universal balance machine which can be utilized as a hard or soft balancing machine. Since the stiffness of the machine suspension is easy and readily changed, hard and soft balancing may be done on the same machine.