Stabilzer Question Charles P WHERE ARE YOU? at DVinfo.net

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Old April 17th, 2005, 02:50 AM   #1
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Stabilzer Question Charles P WHERE ARE YOU?

Ok, im hoping Charles P will join us here and give his excellent comments that he always does. As I get more involved in this hobby of mine, it becomes very addicting and I tend to want to learn more. The purpose of a stabilizer is to maintain the image stable and have a smooth motion like if it were flying. My question is why do they use springs instead of a shock absorber?
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Old April 17th, 2005, 04:08 AM   #2
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"My question is why do they use springs instead of a shock absorber?"

Well, what do you understand is the purpose of a shock absorber? Yes, of course to "absorb" shock, but to explain where I'm coming from, I'll offer you 2 motor car scenarios:

1 - Remove the shock absorbers - This will give you a very "sicky" ride with the car bouncy up and down - nasty! The up and down movement will not have any dampening.

2 - Remove the springs - This will give you a very "hard" ride. There will not be any dynamic "give" in the system. The shocks are not "absorbing" the dynamic up and down moving and allowing the car chassie move independent of the upward thrust of the road surface.

So, a motor car needs both.

Back to your question. Using just absorbors will make the system not very dynamic at all. Using springs makes the system dynamic. What is assisting the dampening are your arms! I think these are the dampeners in this system. There are also adjustments to assist with the dampening - so maybe these are the shock absorbing elements you are requesting to be used?

I suppose the alternative question would be, "When does a spring become a shock absorbor and when does a shock absorbor become a spring?" It is all a matter where these items are used within a dynamic system. Springs have a certain shock absorbing element as do shock absorbors have a dynamic response, acting "like" a spring.

Does this shed any light on your great question? Or have I made it worse for you .. . ?

Shocking stuff Physics!

Grazie
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Old April 17th, 2005, 04:34 AM   #3
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Awesome REPLY! Makes total sense, I appreciate you sharing your comments. Anymore people are also welcome to add to Graham Bernard's reply.
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Old April 17th, 2005, 05:07 PM   #4
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Graham,

Actually your arms are not providing any dampening when wearing a body-mounted stabilizer. Remember, the spring-loaded support arm of the stabilizer is connected to your hip! In fact, your arms can actually cause INstability in the sled if too forceful of a touch is applied (as determined by many different factors).
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Old April 17th, 2005, 05:58 PM   #5
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The answer is even simpler. A true shock absorber is not designed to carry a load while a spring is. The springs in a Steadicam type stabilizer exert a force equal to the weight of the entire rig in order to make it "float in midair". Afterall, something has to be holding it up and it's not magic!

A shock absorber, or dampener, is only designed to restrain bouncing motions (oscillations) once those motions have started. Sometimes shock absorbers have springs or high pressure gas built into them so they look like a plain shock absorber but those can support a load. An example of this are the landing gears of an airliner.

The springs in your car exert the force necessary to "suspend" the chassis and body above the wheels. Hence the term "supension system". But the shocks alone could not hold up the car.
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