Finding engineering data on shock absorbers

Kinda oddball question, hoping that someone will know.
I'm almost ready to re-hang my driveway gate - we've been surviving with
a roll of chicken wire for way too long - but before it goes on it needs a shock absorber to keep it from breaking exactly the way it did before.
(It's a scissors gate, about 120 pounds, 18 feet long and it pivots up and down on one end. It's counterbalanced on springs, but when an enthusiastic kid closes it the crash is a thing to behold -- and a thing to break welds.)
I don't want to cut and try a bazillion different things, and I'm an engineer so I have the delusion that I can design things from first principals.
Is there any place I can find engineering data on vehicle shock absorbers? Not "buy this here shock for that there truck, and get 'em heavy duty if you want to put two cows in there", but real honest-to-gosh tables with numbers and other useful things for folks who are blatantly mis-applying a vehicle shock absorber.
At the least I need things like stroke and mounting data, but something that gives the damping rate of the thing would be uber-cool. In the absence of damping rate a vehicle weight / shock chart would be useful, but it'd be a distant second best.
Stroke and mounting data are obvious (if I can match what's in my truck I'll be quite happy), but if I had the force vs. velocity curves for a number of different shocks then I'd know from the get-go if I'm in the right ball park, and where to put my pivot points, and that sort of thing.
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Googling "shock dampeners" lead to this: http://www.taylordevices.com/pdf/M-series-specifications.pdf Perhaps instead of a fixed device you could use an adjustable heavy- duty door closer, like for a fire door.
jsw
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On Tue, 2 Feb 2010 16:22:43 -0800 (PST), Jim Wilkins

Check Koni and other "race/performance" shocks - they usually have jounce and rebound valving specs and are adjustable.
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Tim Wescott wrote:

http://files.smcetech.com/pdf/newproductpdf/RJ%20Shock%20Absorber%20%28ES20-200A%29.pdf
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On Tue, 02 Feb 2010 19:32:00 -0500, Steve Austin wrote:

28ES20-200A%29.pdf
There's a difference in nomenclature between industrial and American automotive usage.
In industrial usage a "shock absorber" is a thingie that, when you run something heavy into it, absorbs the shock. That's what you've sent me a data sheet for. It's not what I need.
In American automotive usage a "shock absorber" is a thingie that, when you push or pull on it, resists motion with (usually) an increasing resistance force for increasing velocity. In industrial and British automotive usage such a thingie is a "damper". That's what I need.
I'd love to have enough $$ to get an industrial damper, and the contacts to be able to easily buy more when the first one wears out (or if it turns out that I've mis-specified it). But I can swing down to the corner auto parts store and get something that may well be what I need, at an affordable price, on a Saturday, in less than an hour. So if I can use that instead, that's what I want.
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Tim Wescott writes:

Sir, this is a metalworking group. You do not need such data, because you will sand-cast the parts in your backyard foundry and finish them on a lathe in your basement, to whatever specs you like.
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wrote:

Your 120-lb load is much lighter than any vehicle load, and your requirement is mearly to limit velocity rather than to critically damp a resonant mass-spring suspension.
Find a small surplus hydraulic cylinder, make your pivot points compatible with the cylinder's throw, use an adjustable needle valve to achieve desired viscous damping factor.
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On Wed, 03 Feb 2010 00:11:07 -0600, Don Foreman

Or a flow control valve (parallel needle and check) if you only need damping when lowering.
Pete Keillor
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And you may only want damping at the end, just before it closes. If you hook the damper directly to the gate it will slow down the gate for its entire motion, which will be frustrating. Or is that what you want, to be able to just drop it and go? Perhaps mount the damper so that the gate contacts it just before the end, and then it will damp the last foot or so of travel.
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Dennis


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On Wed, 03 Feb 2010 06:28:41 -0600, Pete Keillor wrote:

I like that. I don't think it's going to be small -- 120 lbs on a 9 foot (average) lever arm, working against a cylinder on a lever arm that's effectively less than a foot, adds up to lots-o-pounds.
But a cylinder -- hydraulic or pneumatic -- should be easy to find in lots of sizes, ditto valves, and it should certainly have a wide adjustment range.
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I think a gas strut would work out better. It would provide a constant resistance on the way down. There are many lengths and ratings.
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wrote:

This may help. British Publication
The Shock Absorber Handbook
John C. Dixon, Ph.D, F.I.Mech.E., F.R.Ae.S.
Email (for orders and customer service enquiries): snipped-for-privacy@wiley.co.uk Visit our Home Page on www.wiley.com
ISBN 978-0-470-51020-9 (HB)
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