Machines for balancing mechanical parts (dynamic, static or with an electronic balancing device) e.g., armatures, rotors, crank shafts, connecting rods, propeller shafts, wheels, flywheels. In dynamic machines, the parts are rotated on two bearing blocks or between centres, the out-of-balance being measured mechanically (tracing of diagrams on a recording plate, spring balance principle, etc.). Static balancing machines operate on the tilting principle, the out-of-balance being measured on scales or dials. They differ from dynamic machines in that the part to be balanced does not rotate. Out-of-balances are compensated either by counterweights or removal of material. On machines fitted with an electronic balancing device, the vibrations due to unbalance are detected by a special sensitive element and are then amplified. This heading also covers balancing machines fitted with a machine-tool (drilling-machine, for example) and used exclusively for rectifying out-of-balances.