Abstract: A vibration detector for sensing imbalance of a part in a balancing machine uses an eddy current proximity detector for sensing vibration movement of a portion of the machine. To prevent spurious signals due to magnetic fields varying at the part rotation frequency, a mu-metal can is secured to the vibrating portion of the machine, an electrically conductive coupon is attached inside the can for vibrating movement therewith, and the proximity detector is spaced from the coupon by a small gap for producing AC signals representing the vibration amplitude.

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.