Shock pulse and vibration: a drop in water and a boat on waves
Two ways of looking at a machine. One hears the impacts, the other feels the motion. Together they give the complete picture.
Shock pulse is a drop in water
Think of a drop hitting the surface of water. The impact creates a short, distinct pulse. In a rolling element bearing, the interaction between the rolling elements and the raceway generates short transients that can be measured and evaluated to assess bearing condition.
Vibration is a boat on waves
Here you measure the mechanical vibration at the measurement point. By analysing the signal and its frequency content you can identify patterns that go with different machine conditions: imbalance, misalignment, looseness, gear mesh and resonance.
They complement each other
Neither replaces the other. They look at different characteristics of the machine, and using both builds a more complete understanding of machine condition.
Which to lean on
- Early rolling-bearing damage, especially on slow or heavily loaded machines: an impact-based measurement.
- Imbalance, misalignment, looseness and resonance: vibration spectra.
- Gear wear: both, because mesh harmonics and impacts tell different parts of the story.
- Lubrication film condition: the impact level, trended against grease or oil changes.
- Pump cavitation: broadband high-frequency energy, which climbs as suction pressure falls.