Gas struts

[INSAYN]

Working on designing a platform/lid for the top of my trailer to mount a Maggiolina Airtop tent to. I would like to have this platform be hinged at the front of the trailer, so I can lift the closed tent up 3-4 feet at the rear to ease accessing items near the inside of the front of the trailer. The Airtop is rated at 130 lbs, so I would need a heafty set of gas struts to lift the tent as well as the platform/lid combined. For the sake of overdoing it, lets go with 200+ lbs for everything.

Where would you suggest I look for appropriate struts to handle the weight easily?

 

[dsy]

http://www.mcmaster.com/#catalog/115/1180/=5efub5 :coffeedrink:

The next four or five pages in the catalog will show all the hardware needed also.

 

[nat]

x2 on McMaster-Carr. They should have formulas to help determine what size you need.

 

[StumpXJ]

I got the 250 pounders for mine from McMaster. I have my lid hinged the xact same way you describe.

~ Stump

 

[dsy]

250 pound SS springs here also which work great when the RTT is mounted. When the RTT is not there I just unhook one spring and the top is sprung perfectly again.

 

[INSAYN]

Sweet, thanks.

 

[BigDaveZJ]

x whatever on McMaster Carr, used them for ours as well.

 

[INSAYN]

I started researching gas struts for my trailer lid today and e-mailed McMaster for some help in selecting a set of struts for the job, and maybe a diagram on the proper way to set them up.

In a nutshell I was told that they don't make recommendations for applications.


:088:

Alrighty then.... Back to square one.


So, I went about searching for some kind of gas spring selection calculator online. I found one that takes just about everything into consideration, only it is all in metric. And I suck at the metric to SAE conversions.
http://www.bansbach.de/com/gasfedern/online-calculator-3.html

I converted everything I could figure out, and configured the layout based on a set of two McMaster struts rated for 250lbs each from the link provided earlier.
http://www.mcmaster.com/#catalog/115/1180/=bdl8y4

I am working with the 250lb M8 strut that follows:
(A) 29.33" (745mm), (B) 15.56" (395mm), (C) 13.77" (350mm), (Rod Dia) .39" , (Cyl Dia).87" .

In the picture you can see the formula values on the right side and the layout on the bottom left, and manual force in the upper left.

My lid is 83" (2108mm) long, 1.5" high, 57" wide and with the Maggiolina Airtop mounted on it, it is going to be somewhere between 200 and 300lbs (weight of flap).

I figure I'll mount the strut 1" (25mm) below the lid, and keep the lid opening limited between 30"-36" which works out to be between 20 and 25 degrees with the strut fully extended.

Here is where I am stuck. I'm not entirely sure if the strut has to be right at the center of gravity, or if it is safe to push it further from center, leaving more weight towards the hinge like I have it right now?

Also, kinda lost on the Manual Force, and Manual Force Angle part and how it relates to the graph in the upper left. When I tweak these, I don't understand what I am changing in regards to how the lid will react.



If anyone would like to play with the calculator and see if I am on the right track or if I'm way out there. Any suggestions would be great.

 

[refried]

Here's mine

I looked at what struts were available in the legnth I wanted, lifted the lid, guessed the weight, added the weight of the boat, and split it in half. Worked out perfect, opens with one hand without the boat on it, and with too hands with the boat. It will stay up with the weight of the boat on it, but I put a support under it just in case (deck + boat weigh about 300 lbs.). I got my struts at NAPA but don't remember the size.

 

[INSAYN]

Thanks for the reply Refried. I looked on NAPA's website and it took a bit to figure out what they were calling them. Not gas struts, not gas springs, not lift spring, not lift strut, but lift support. Whodah thunk that?

Anywho, they only give compressed length, and extended length, and of course price, but nothing referring to lift capacity.

Maybe I'll wander over to our local NAPA and start asking questions. :smiley_drive:

 

[refried]

I think I had to look in an old old paper accessory catalog to find the capacity. I may have 2 250 lb struts on there, I really don't remember, they were some of the longest and heaviest they had.