Electronic systems need transporting with care. Sudden impacts, as if dropped from the back of a truck, can pop IO cards out of their slots, disconnect cables, and damage hard drives. That’s why you’ll often see acceleration or g-force limits called-out in specification documents for many electronic products.
A transit case protects against shock impacts by suspending the payload in the center of the case and away from the sides. When the case stops moving suddenly, as when it hits a concrete floor, the suspension system lessens the g-force experienced by the payload.
The suspension system must be matched to the mass of the payload. And, the chosen case size must let the payload sway and come to rest without hitting the interior walls. Wire rope systems are often used for heavier payloads while elastomeric systems perform well in lighter duty applications. There’s more information on this in the blog post “How Transit Cases Prevent Shock Impact Damage.”
One frequently-asked-question is, “How much shock reduction does the suspension system provide?”
This can be estimated from knowledge of the payload and the suspension system. But, the best way to really find out is through instrumented testing. As the video shows, accelerometers are mounted in a block the size and weight of the payload, secured inside the case, and hooked to a data capture system. The case is raised and then dropped onto a hard surface. The accelerometers record the g-force experienced by the payload.
This test can be carried out from any height necessary to replicate the worst-case in-service conditions. In many applications, that means a drop up to 48 inches, the typical height from a semi-truck bed and loading dock. Many military projects have specific drop-height requirements. As seen in the video, the test is usually repeated with the case in different orientations as there’s no way to predict how it might fall.
Computers, radios and similar electronic equipment are easily harmed by shock impacts. Engineering a means of controlled deceleration into the transit case reduces the risk of mission-ending damage. And, testing ensures it performs the way it should.