A chart looks like a mess of lines until you know that it is only ever telling you three things. Learn those, and the rest is practice.
1. Magnitude, how far the trace moved
Each stylus rests near the centre of its lane and deflects when the instrument accelerates. The distance it travels is the size of the event. A trace that wanders gently is a shipment riding well. A trace that spikes hard and returns is an impact.
Read the deflection against the printed lane scale, not against your intuition. On a recorder calibrated to within 4% of full scale, that number means something.
2. Axis, which stylus wrote it
On a three-axis recorder each lane is one direction: longitudinal, lateral, vertical. This is the part most people skip, and it is usually where the answer is. A hard vertical spike with nothing on the other two lanes is a drop or a hard set-down. A longitudinal spike alone is a coupling or braking event. Spikes across all three at once are a genuine impact rather than handling.
3. Timestamp, where along the chart it sits
The chart advances at a fixed, known rate, so position along it is time. That converts “something happened” into “something happened on the fourteenth day” , which, cross-referenced against the routing, converts into which leg, and often whose custody.
Putting it together
A receiving clerk who can read magnitude, axis and timestamp can do something a photograph of a dented crate cannot: state what the freight experienced, when, and in which direction, against a threshold your packaging engineer set in advance. That is the difference between an argument and a record.
Annotated sample charts for each recorder come with the interpretation guide on the product pages.