The operation of P.C.M. FR series timing gears is based on the principle of planetary gearboxes, with the difference that the outer ring is not integral with the body but is coupled to a worm gear.

By turning this worm, known as a corrective worm, it is possible to increase or decrease the output speed while keeping the input speed unchanged, or rather to change the reciprocal positions between the input and output shafts.

This is why timing gears find wide application in all those sectors where it is necessary to maintain synchronisation or movement timing between the different phases of a machining operation.