A look into the vibration and shock ratings on the AMOT EH Series electric rotary actuator, and the design choices that earned them. Shop our quarter-turn actuator series here.
Why vibration and shock resistance matter
Where do AMOT actuators actually live? Bolted to a running engine. Riding on a haul truck. Aboard a naval vessel. That means sudden stops, rough terrain, and constant shaking, in an environment that finds the weakest part of an assembly and pushes on it until something gives.
The EH Series is rated to handle it all. In this post, we explain why these conditions are so hard on a component and how AMOT tested the actuator to back up its numbers.
Breaking down the vibration specification
The EH Series is rated for 14.1 GRMS, 10 to 1000 Hz, 20 hours per axis. Here is what each of those numbers means.
14.1 GRMS is the root mean square acceleration of the vibration profile. It describes the overall intensity of the vibration across the full profile instead of the size of any one peak.
The profile is random vibration. A sine test excites one frequency at a time and moves through the range in sequence. A random profile excites every frequency in the range at once, which is much closer to what a running engine does to the equipment bolted to it.
10 to 1000 Hz is the frequency range the profile covers. Frequency is how many times per second something shakes, measured in hertz.
An engine shakes at many frequencies at once. A six-cylinder four-stroke running at 1,800 RPM fires 90 times a second. Gear trains produce tones in the hundreds of hertz, and a turbocharger adds higher frequencies on top of that. All of it reaches the actuator at the same time, through the same mounting surface.
The width of the range matters because of resonance. Every physical part has a natural frequency it tends to flex at, the way a tuning fork rings at one pitch. When incoming vibration matches that frequency, the part’s motion is amplified, so a small input can produce a large movement. There is no way to know ahead of time which capacitor, bracket, or fastener will resonate at which frequency, so the test has to cover the whole band. 20 hours per axis is the dwell time, applied in each of the three axes. That adds up to 60 hours of random vibration, long enough to bring out fatigue failures that a short qualification run could miss.
Mechanical shock: MIL-STD-810G, Method 516.6, 40G
Vibration builds up damage over hours. Shock delivers it all at once.
A 40G pulse is the kind of jolt an actuator sees when a haul truck drops into a rut or when heavy equipment takes a hard hit in service. Vibration can take hours to fatigue a solder joint. A shock event can crack one in milliseconds.
The EH Series is qualified to MIL-STD-810G, Method 516.6, at 40G. The standard defines how the shock pulse is applied, so results can be repeated and compared between manufacturers. It is also widely referenced in military and defense equipment specifications, which gives program engineers a known starting point when they evaluate the actuator for their platform.
Why these numbers are hard to hit
Surviving a 14.1 GRMS profile takes more than building something heavy. Vibration and shock resistance depend on where the mass sits, how the joints are designed, which components go on the board, and how the housing carries the load. Those decisions have to be made at the start of a design.
When a component fails in these conditions, it usually fails in one of four ways:
- Solder joint fatigue. Repeated flexing cracks the connection, often before anything looks wrong with the component itself.
- Fastener loosening. Over thousands of hours, fastener torque relaxes, preload drops, and parts start to move where they shouldn’t.
- Connector fretting. Small movements at the contact surfaces wear through the plating and raise resistance until the signal degrades.
- Lead flex. Any component standing proud of the board acts as a lever arm against its own solder joints.
The EH Series design addresses that last one directly, and it started with a decision made early in development.
Surface mount construction for high-vibration service
Many electronic assemblies use leaded, or through-hole, components. Each part has wire leads that pass through the board and are soldered on the reverse side. In a stable environment, that construction holds up well. In a high-vibration environment, the leads can flex, fatigue, and crack at the joint.
Every component on the EH Series control board is surface mount. Each part sits flat against the board and bonds directly to its surface, with no leads to flex and a low profile that keeps leverage on the solder joints to a minimum. Put a leaded board next to the EH Series board and the difference is easy to see.
"From a vibrational standpoint, all of the components on the board are surface mount devices, very low profile to the board. Compared to industrial actuators that use leaded types of devices, in a high vibration environment that's definitely a point of failure."
Jeff Schonhoff, Engineering Director, AMOT Controls
The rest of the assembly follows the same approach. Mass is kept low and close to the mounting surface, and parts that could move under load are held in place so they can’t set up their own resonance.
Holding the specification over a million cycles
Passing a vibration profile once shows the design will hold together. It doesn’t show that the actuator will still meet its torque, timing, and sealing numbers after years in service. That requires endurance testing.
The EH Series is rated for 1,000,000+ cycles at rated load and 100% duty cycle at maximum rated load and maximum rated temperature. Both ratings were confirmed through physical testing.
Test equipment for this kind of work is hard to find off the shelf, so AMOT designed and built its own rigs to run million-cycle endurance tests at load and temperature.
"A lot of the test equipment required to validate the EH Series is not generally available in the marketplace. So we had to go off and design and build our own test equipment to characterize the actuator performance."
Jeff Schonhoff, Engineering Director, AMOT Controls
A single million-cycle run takes six to eight weeks, and the design went through several of them before the ratings were finalized.
Where the EH Series is used
These are everyday operating conditions for equipment that runs around the clock:
- Engine-mounted control on diesel and gas engine packages, where continuous vibration and thermal cycling run together.
- Oil and gas fracturing, where equipment runs at high load through dirt, heat, and cold.
- Naval and marine systems, where equipment has to handle constant motion, vibration, and water exposure.
- Military and heavy mobile equipment, where MIL-STD-810G testing is often part of the requirements.
In each of these applications, the cost of a failed actuator goes well beyond its purchase price. It shows up in replacement parts, unplanned downtime, and maintenance labor. Reliability is the real measure of value.
EH Series vibration and shock specifications at a glance
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Features: |
EH Series |
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Vibration: |
14.1 GRMS random, 10 to 1000 Hz, 20 hours per axis |
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Shock: |
MIL-STD-810G, Method 516.6, 40G |
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Endurance: |
1,000,000+ cycles at rated load |
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Duty Cycle: |
100% at maximum rated load and temperature |
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Operating Temperature: |
-40°C to 125°C |
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Ingress protection: |
IP67 and IP69K |
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Torque: |
25 Nm and 125 Nm, 24VDC |
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Certifications: |
CE, UKCA, EMC, MIL-STD-810G |
Both torque models share the same operating ratings, vibration resistance, sealing, controls, and duty cycle. Choose the torque your application needs, and everything else stays the same.
Frequently asked questions
How much vibration can the EH Series withstand?
The EH Series is rated for 14.1 GRMS random vibration across a 10 to 1000 Hz band, tested for 20 hours in each of three axes.
What does GRMS mean on an actuator specification?
GRMS is the root mean square acceleration of a random vibration profile. It describes the overall vibration intensity across the full frequency range. Random vibration testing is also closer to real engine conditions than a single-frequency sine test.
What does the 10 to 1000 Hz frequency range mean?
Frequency is how many times per second something shakes. An engine produces many frequencies at once, from firing pulses in the tens of hertz to gear and turbocharger content in the hundreds. Testing across the full 10 to 1000 Hz range helps find any component that resonates anywhere in that band.
Has the EH Series been shock tested to military standards?
Yes. The EH Series is qualified to MIL-STD-810G, Method 516.6, at 40G. MIL-STD-810 is widely referenced in military and defense equipment specifications, though each program sets its own test requirements.
Why does surface mount construction matter in high-vibration environments?
Leaded components stand above the board, so under vibration they act as lever arms against their own solder joints, which can lead to fatigue cracking. Surface mount components sit flat against the board with no leads to flex, which removes that failure mode.
Can an electric rotary actuator be mounted directly on an engine?
Yes, if it was designed for it. Engine-mounted service combines continuous broadband vibration, thermal cycling, and exposure to fluids, dust, and washdown. The EH Series was designed around those conditions from the start.
See the full specification
The complete EH Series specification sheet covers torque, operating temperature, duty cycle, sealing, and control options for both models.
Download the EH Series spec sheet
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