Method and apparatus for detecting gear defects

A method for detecting gear defects in a system having at least four gears comprising the steps of:

• collecting signal data relating to the interaction of a first pair of gears including a first gear and a second gear;
• collecting signal data from a second pair of gears which includes a third gear which interacts with a fourth gear, said third and said first gear being located on a common shaft;
• combining the signals collected from said first, second, third and fourth gears together to form a giant hunting tooth pattern;
• and,
• detecting the envelope of said giant hunting tooth pattern,
• wherein the period of the peaks of the envelope which corresponds to the hunting tooth of either pair indicates on which pair of gears a defect is likely to be found.

A method of analyzing a vibrational signal generated by the inter-meshing of at least two gears, said analysis comprising the steps of:

• sensing said vibrational signal at least long enough for each tooth of said gears to mate once before repeating;
• stacking at least two of said signals so that identical tooth-to-tooth matings are superimposed on each other;
• and
• determining which tooth-to-tooth interactions have anomalous patterns,
• wherein the tooth-to-tooth interactions which have anomalous patterns determined above are likely to include a gear having a defect therein.

A system for analyzing a vibrational signal generated by at least two inter-meshing gears, said system comprising:

• a vibrational signal pickup mountable on an object;
• an interface connected to said pickup;
• an analog signal processor means connected to said interface for conditioning and converting said signal to a digital signal;
• a computer means connected to said analog signal processor means for recording the digital signal over at least one hunting tooth period of said gears and stacking at least two of said signals so that tooth-by-tooth interactions are superimposed on each tooth;
• and,
• an output means for reporting the results of the operations performed by said computer means.

A method of detecting the location of a defect in a gear system of at least two gears, said method comprising the steps of:

• generating a series of hunting tooth patterns of the tooth-by-tooth interactions of at least two gears;
• and,
• comparing the hunting tooth patterns generated over time against each other to locate local gear defects,
• wherein said hunting tooth patterns are as long as it takes for each tooth-by-tooth interaction to repeat itself.

A method for analyzing a vibrational signal generated by at least two inter-meshing gears, comprising the steps of:

• detecting said vibrational signal;
• high frequency band pass filtering said vibrational signal;
• detecting the envelope of said high frequency band pass filtered signal to produce a signal representative of the low frequency components of said vibrational signal;
• and,
• stacking at least two of said envelopes so that vibrations of the same tooth are superimposed on each other,
• wherein the stacking of said envelopes produces an indication of gear tooth anomalies.