Shock mounting solutions for shelter radio gear?

[professor solderflux]

I'd be interested in hearing from anyone on ideas for improvised shock mounting for the various electronics, computers, and radios that one would place inside a shelter. I know some shelters come with equipment mounting shelves and tie-down web straps (mine did not), but usually not any provision for protecting and isolating the equipment from road shock. A good set of leaf springs helps, but a rutted road or potholes can still deliver quite a jolt (Illinois roads are the worst I'VE seen!).

I can fabricate some rigid shelving for my shelter to house the computers and radio gear, but I'm not sure what to do about cushioning the equipment's case from the shelf. Commercial isolation mounts are around $8 each plus shipping, so at four mounts per shelf--OUCH! Instead I was thinking about getting some 1/2" GI sleeping pads (24" x 72"), and cutting them to fit each shelf, and using OD straps and footman loops to secure the equipment to the padded shelf.

Opinions, or other ideas welcomed...

 

[cranetruck]

I'd think that would be a rather complex engineering problem.
The radio gear can handle a certain amount of banging around, but may be more sensitive to some frequencies. The stiffness of the rubber mount will determine what kind of vibration is transferred to the equipment etc.

Leaf springs have built-in damping from the friction between the leaves (never lubricate leaf springs), but if additional damping is required, adding shock absorbers to the rear of the truck will dampen higher frequencies.

To begin with, learn about the equipment and find out how much it can tolerate. Lots of things to consider...

 

[Whiterabbit]

Hi, check out Grainger,MSC and EnCo for vibration isolation mounts. Alot of different styles and specs. You name it,they got it. Mount your gear on a board/plate and put the isolators between board and shelf. They have some that look military too.

 

[Q710M]

I've heard that this type can work well:
http://www.thevmcgroup.com/PDFs/wirearx.pdf
(...probably quite expensive though)

 

[professor solderflux]

Thanks Q710M. That's an interesting approach, and a new one for me--kind of makes the rubber mounts look antique.

You're probably right about the prohibitive cost though--still interesting to consider. The math looked a little intimidating at first, but it's just algebra.

I had asked Ben at Ontario Surplus the same question from the start of this thread. He emailed a response that I'll include here for anyone else's benefit. He's an engineer, and has a similar approach to the link you posted. Thanks again for the help, everyone.

"Shock mount design is somewhat complicated. It is relatively easy to add an isolation mount and actually amplify the vibration seen by the equipment due to the natural resonant frequency of the mounts and the mass of the equipment. As a result, it is very important to understand the characteristics of the isolators, the mass of the equipment and the frequency characteristics of the vibration that you are trying to isolate. I have some experience from a design I did for a locomotive application, but I don't have enough experience with automotive applications to provide good guidance on the vibration environment to design for.

If you aren't concerned about operating the equipment during transportation, vibration is less of an issue and your primary concern will be shock. Almost anything you do will help some. Probably the most important thing is to have a really good way to secure the equipment. The trailer suspension alone will provide significant protection from large shock, but a unit bouncing around on the floor won't benefit from it. Vibration during transportation can cause all sorts of issues with connectors and other mechanical items. If you can build a mount system that has a natural frequency under 50 Hz, you'll probably significantly reduce most vibration in your application and it won't be so soft that it will be easy damaged by shock. Also, if you mount a generator to the trailer, it can be a significant source of vibration. Calculate the rotational frequency of the engine and it should be well above the natural frequency of the mount system. Unless you are using a low speed diesel, you should be fine with the 50 Hz guideline above."

 

[cranetruck]

Here you go.
(No sunlight yet, better picture later if you want)

 

[Whiterabbit]

Qute true

Yes there is a big difference between shock protection and vibration protection. Most Military gear is built to withstand vibration of a bumpy dirt road but hitting a killer pothole might knock things loose inside. The industrial supply stores like Grainger and Enco have mounts but doubble check that they are for shock loads, they will probably be softer. Good prices too and most towns have a Grainger store in the industrial side of town.
PS. get their free big book from the counter.

 

[avengeusa]

I have been thinking about a shock mitigation system also, i want to mount a std cb radio, but am concerned with breakage

 

[jesusgatos]

I need to address vibration in my M109 camper too. I'm going to have a computer desk / workstation / office in there, and we've built a cabinet to hold the computer. I was just planning on wrapping the corners/edges of the computer with some type of insulating mat (sort of like how you see radiators mounted in a lot of off-road race trucks), and then securing it to the slide-out tray. Let me know if there's a better option.