Does EN 50155 itself define the vibration test profile?

EN 50155 sets the overall requirements for electronic equipment on rail vehicles and references IEC 61373 for shock and vibration qualification. The numeric profiles, axis counts and durations come from IEC 61373, which is why a compliance claim should always cite the mounting category tested.

Why does mounting category matter more than enclosure thickness?

Random vibration excites the resonance of the whole mounted assembly, not just the housing. A thick enclosure on a compliant bracket can still amplify input, while a lighter unit on a stiff, correctly loaded mount stays below damaging acceleration levels.

Is optical bonding necessary for shock resistance?

It is not mandatory, but it removes the air gap that lets cover glass and display cell move independently under shock pulses. Bonding couples the layers into a single member, which reduces perimeter adhesive fatigue and also improves readability in bright ambient light.

What installation detail most often invalidates a qualified unit?

Unsupported cabling. Laboratory testing normally uses short, clamped harnesses, so a field installation that leaves connectors carrying the weight of a long cable run introduces a load path the qualification never covered.

Should rotating storage ever be used in these applications?

No. Mechanical drives have moving heads and bearings that are sensitive to both sustained vibration and shock pulses. Solid-state media rated for the intended temperature and mechanical profile is the appropriate choice.

EN 50155 Shock Limits and Impact on Rugged All in One PCs

Two identical terminals can carry the same ingress rating and fail on completely different schedules once vibration enters the picture. EN 50155 governs electronic equipment on rail vehicles and references IEC 61373 for mechanical qualification, which subjects a unit to random vibration and half-sine shock pulses across three axes. Those limits increasingly appear in tenders for mobile mining plant, port cranes and mine hoist rooms, so a rugged all in one pc specified against them behaves differently from an office-grade box sitting in a static cabinet. The standard does not simply demand thicker metal. It changes how the assembly is fastened, how displays are bonded and how cables leave the chassis.

Rugged all in one pc bolted to a steel frame in a mine hoist control room — Mounting location decides the qualification category, since frame-mounted units see far higher input than body-mounted ones.

Within IEC 61373 Categories and Mounting Location Limits

IEC 61373 separates equipment by mounting location, since a body-mounted unit sees far gentler input than one bolted to a bogie or axle. Category 1 body mounting is typically qualified with random vibration in the 5 to 150 hertz band for several hours per axis, followed by shock pulses in the range of 30 to 50 meters per second squared with a duration near 30 milliseconds. Category 2 mounting raises those figures substantially. Procurement teams frequently copy a clause without recording which category applies, and the resulting specification either overspends on a hardened enclosure or under-protects the assembly. A rugged all in one pc intended for a hoist room floor does not need bogie-level qualification, but it does need documented evidence at the category it will actually occupy. Reviewing the test report matters more than reading a marketing claim, because a functional test performed during vibration proves far more than a pass judged only by post-test inspection.

Aluminum alloy industrial pc mounted on elastomeric vibration isolators inside a machinery cabinet — Elastomeric isolators only damp effectively when loaded within their rated range, so mount selection follows assembly mass.

Fastening and Damping Choices That Survive Random Vibration

Random vibration finds resonance rather than brute strength. A flat steel bracket with widely spaced bolts can amplify input at its own natural frequency, so the mounting design should push the assembly resonance well above the excited band or damp it deliberately. Elastomeric isolators achieve that, though they only work when the mount is loaded within its rated range, and an under-loaded isolator transmits nearly everything. Internal details matter equally. Board-level connectors need retention hardware, memory modules benefit from mechanical clamping, and any rotating storage device should be replaced by solid-state media rated for the same profile. Because thermal paths often depend on screw preload, loosening under vibration quietly raises junction temperatures long before an outright fault appears. Design approaches like those adopted in the KOXIAN K2 series treat the machined aluminum frame as both heat spreader and structural member, which reduces the number of independent load paths that can shift over time.

Clamped bulkhead cable entries and service loops on a rugged industrial all in one computer — Anchoring each harness close to its entry point keeps shock energy out of connector solder joints.

Display Bonding and Cable Strain Relief Under Shock Pulses

Half-sine shock pulses concentrate stress at the largest unsupported mass, which in most integrated terminals is the display stack. An air-gap assembly lets the cover glass and liquid crystal cell move independently, and repeated pulses work the perimeter adhesive until delamination or a bright edge appears. Optical bonding fills the gap with resin and couples the layers into one member, which also removes internal reflection and improves daylight contrast. Cable entries fail next, since an unsupported connector shell transfers pulse energy directly into solder joints and pin retention. Service loops, clamped bulkhead entries and threaded circular connectors distribute that load into the chassis instead. In practical automated production lines, systems incorporating KOXIAN-based hardware units keep signal integrity through sustained mechanical input because the harness is anchored within a short distance of each entry point. A rugged all in one pc that passes qualification with laboratory cabling can still fail in service when the installer leaves an unsupported cable hanging from a moving frame.

Mechanical standards written for rail service have become a convenient shorthand for durability in other mobile applications, but the shorthand only helps when the mounting category, test report and installation practice are read together. Assemblies that push resonance out of the excited band, bond the display stack and anchor every cable entry tend to survive the profile they were purchased against. Those that rely on enclosure thickness alone usually reveal their weakest joint early in service, long before the warranty period ends.