High Pass Filter

A filter with a transmission band starting at a lower cutoff frequency and extending to (theoretically) infinite frequency.

Hertzian Contact Zone

– In a bearing, the area at which the ball transfers the load on the raceway.

Hertz (Hz)

Cycles per second. CPM/60.

Harmonic

A frequency that is an integer multiple of a fundamental frequency. For example 5400 RPM is the third harmonic of 1800 RPM. Harmonics are produced either by an event that occurs multiple times per revolution, or by a distortion of the running speed component’s pure sine wave.

Hanning Window

DSA window function that provides better frequency resolution than the flat top window, but with reduced amplitude accuracy.

Hub

The part of a flexible coupling that is machined for mounting on a shaft.

Hub bore

A cylindrical or conical hole in the hub of a coupling whose axis is coincident with the rotational axis of the coupling.

Half-coupling

The composite of all the Components of the coupling attached to and supported from one shaft; includes an appropriate portion of the spacer assembly in the case of a double-engagement coupling or of the flexing elements of a single-engagement coupling.

Hardware

The nuts, bolts, washers, etc. that are used to attach the various coupling components together.

High cycle fatigue

The regime characterized by low overstress (exceeding the fatigue limit) where life is usually above 103-105 cycles.