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1981 Cobra trailer gas struts



 
 
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  #11  
Old December 15th 19, 01:41 AM posted to rec.aviation.soaring
David Cleveland
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Default 1981 Cobra trailer gas struts

Dennis, you have a trailer with the struts on the outside? And 1100N wasn't too much to pull down? That's good to know. I don't want to get into the situation Dan describes. I've seen that a few times myself.
  #12  
Old December 15th 19, 02:30 AM posted to rec.aviation.soaring
Nick Kennedy[_3_]
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Default 1981 Cobra trailer gas struts

On Friday, December 13, 2019 at 5:54:33 AM UTC-7, David Cleveland wrote:
I have a 1981 Cobra trailer designed for a single seat glider. The trailer design is of the type that has the struts located on the outside of the trailer, with an aluminum top. I am looking to replace the gas struts.

I have contacted Wings and Wheels. They have been very helpful, but they do not carry the struts for this design. They also mentioned that Spindelberger/Cobra do not carry the item.

I am looking for two things. My struts were painted in the past, so I am unable to get the read the strength of the strut. I am also looking for a recommendation for replacement or refurbish.

Thanks

David Cleveland
Salt Lake City


Dave I've got the same trailer
When my Lift struts failed they were the 900 version
I replaced them with 1100 from Williams and they work great.
No lifting [ or very very little ] and I can pull it down with no problem to close it.
I think would would be happy with the stronger struts.
Be careful when you change them as you know, that top is heavy and if it were to fall on you it could kill you.
Safe Flying
T
  #13  
Old December 15th 19, 03:19 PM posted to rec.aviation.soaring
David Cleveland
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Default 1981 Cobra trailer gas struts

Thanks Nick. That's good to hear. Sounds like 1100N gas struts are the way to go. If W/W has no way to get the struts I'll work on some of the second party manufacturers. I had a good talk with Richard yesterday. He gave me a good steer, as well as a few cautions I hadn't thought about.

Yeah, I've had my struts off before and I've worked on the same kind of trailer for friends. Those tops are surprisingly heavy.

DC

  #14  
Old December 15th 19, 04:12 PM posted to rec.aviation.soaring
Clay[_5_]
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Default 1981 Cobra trailer gas struts

If all else fails McMaster Carr sells some adjustable force gas springs that I have on my trailer (not a Cobra). They might fit.
  #15  
Old January 6th 20, 04:38 AM posted to rec.aviation.soaring
Matt Herron (Sr)
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Default 1981 Cobra trailer gas struts

I have a new pair of Cobra struts that I would be happy to sell, cheap.
These are the stats: N= 850; Art-Nr = 3 500 30; Herst-Dat = 0605
Dont\'t ask me what these figures mean. I have no idea!
  #16  
Old January 6th 20, 05:00 AM posted to rec.aviation.soaring
AS
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Default 1981 Cobra trailer gas struts

On Sunday, January 5, 2020 at 10:38:23 PM UTC-5, Matt Herron (Sr) wrote:
I have a new pair of Cobra struts that I would be happy to sell, cheap.
These are the stats: N= 850; Art-Nr = 3 500 30; Herst-Dat = 0605
Dont\'t ask me what these figures mean. I have no idea!


850 Newton force, Manufacturing Date June 2005.
The 3 500 30 is the mfg's article number.

Uli
'AS'
  #17  
Old January 6th 20, 09:47 AM posted to rec.aviation.soaring
David Cleveland
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Default 1981 Cobra trailer gas struts

On Sunday, January 5, 2020 at 8:38:23 PM UTC-7, Matt Herron (Sr) wrote:
I have a new pair of Cobra struts that I would be happy to sell, cheap.
These are the stats: N= 850; Art-Nr = 3 500 30; Herst-Dat = 0605
Dont\'t ask me what these figures mean. I have no idea!


Thanks Matt. The strut force is a bit light for what I need. The trailer I have calls for at least 900N, but most input I've received is that 1000N to 1100N works best.

David
  #18  
Old January 7th 20, 10:26 PM posted to rec.aviation.soaring
[email protected]
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Default 1981 Cobra trailer gas struts

Re the 2005 manufacturing date: 850 newtons is almost 200 lbs. That's more difficult to measure by hand than an LS landing gear spring or a canopy spring, but it might be advisable to do so. Gas springs don't last forever.

They (and I use that word intentionally) deteriorate on the shelf. The pressure inside the cylinder is still very high even when it's in the extended position. I've seen figures of 1% to 2% loss per annum, which adds up. After they're installed, dust or grit getting into the seal can result in much faster deterioration in force.

When storing a gas spring/strut, hand or position it with the piston rod pointed down. The oil in the cylinder will pool in the bottom of the cylinder and help maintain the seal there. Never store them upside down or laid flat, say, on a workbench or in a toolbox. I learned this the hard way back in my LS-3 landing gear gas strut days when I smugly pulled out the bright, shiny-looking spare I'd carried for several years and was crestfallen to find it was as weak as the one I pulled out of the glider.

This also applies to installation. Given a choice, most of the advice I read is to install in a position where the piston end will be lower than the cylinder end most of the time. It may be (e.g., in my old LS-3, IIRC) that it's positioned one way when the wheel is up but the other way when the wheel is down.

Chip Bearden
JB


  #19  
Old March 17th 20, 04:37 PM posted to rec.aviation.soaring
[email protected]
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Default 1981 Cobra trailer gas struts

Guys it's been a while since I followed up on this post. I located a manufacturer in Oregon that will make custom size and force gas struts. The company is called American Gas Springs. They have a website if you want to check it out.

Richard Pfiffner ordered a couple for his Cobra trailer and they worked fine. I am in the process of ordering some as well. I've had some difficulty getting a response, but I thought I'd put it out in case there was anyone else who wanted to add on to the order.

Right now I am ordering standard sized Cobra struts for pre 1984 trailers. These are the trailers with the struts on the outside. I am also ordering the same for a Komet trailer of the same vintage. If you want to PM me I can give you my specs.

David

On Friday, December 13, 2019 at 5:54:33 AM UTC-7, David Cleveland wrote:
I have a 1981 Cobra trailer designed for a single seat glider. The trailer design is of the type that has the struts located on the outside of the trailer, with an aluminum top. I am looking to replace the gas struts.

I have contacted Wings and Wheels. They have been very helpful, but they do not carry the struts for this design. They also mentioned that Spindelberger/Cobra do not carry the item.

I am looking for two things. My struts were painted in the past, so I am unable to get the read the strength of the strut. I am also looking for a recommendation for replacement or refurbish.

Thanks

David Cleveland
Salt Lake City


  #20  
Old March 17th 20, 05:11 PM posted to rec.aviation.soaring
David Cleveland
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Posts: 28
Default 1981 Cobra trailer gas struts

Yeah. Whoops. That last post was from David Cleveland. I was using someone's else's computer.

David
 




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