The instinct when specifying a shock threshold is to pick a low number, on the theory that a more sensitive instrument is a more protective one. For heavy equipment this is backwards, and it fails in both directions at the same time.
It misses what actually causes damage
Large mass moves slowly. The events that damage a 40-ton transformer are long-duration, relatively low-peak accelerations, a rail coupling, a bad crane set-down, sustained ocean swell working a poorly secured load. A threshold indicator tuned for sharp, brief impacts can sit through all of it without tripping, and arrive looking like nothing happened.
It trips on everything harmless
Meanwhile a 10G threshold on that same freight will fire during ordinary handling that does no damage whatsoever. After the third false alarm, the receiving dock stops treating the indicator as information. An instrument everyone has learned to ignore is worse than no instrument, because it occupies the space where a real one would be.
What to do instead
- Start from the cargo, not the instrument. What acceleration does this equipment actually not survive? Your packaging engineer usually knows, or can derive it.
- Prefer a continuous record over a threshold. A recorder that writes everything lets you set the threshold afterwards, in analysis, instead of committing to a guess before the shipment.
- Size for the route. Rail, road, ocean and air produce different signatures. Multi-modal moves should be specified for the harshest leg.
Send us the cargo weight, the packaging design and the route, and our engineers will recommend a range rather than sell you the most sensitive thing on the shelf.