Hatch Gas Spring/Strut Calculator

[billyq]

Thanks for the calculator and discussion. My original struts were way too short, and I spent a lot of time messing around trying to figure out how to make them work, before your calculator helped me get the correct ones, installed in the right place.

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[fimg=]2021-02-06 09.54.43.jpg
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[danlott]

Thanks for the calculator and discussion. My original struts were way too short, and I spent a lot of time messing around trying to figure out how to make them work, before your calculator helped me get the correct ones, installed in the right place.

Thanks for letting me know well the calculator helped you.

Dan

[danlott]

I don't get on here a lot, but I do check in from time to time. If anyone has any questions about how to use the strut calculator or placement feel free to comment in this post or send me a private message.

Dan

[wdieck]

Thanks for the calculator. I used the calculator/simulation tool at http://www.gasspringsshop.com to determine the strut length I needed and then your tool to verify the force. Then I made a video about the process!

https://youtu.be/BWHYFHLIFWA

[Vaughn771]

Hey there! Question about the weight rating for the struts: When I get the weight at 50% hatch length, do I get EACH strut to lift about that weight? Or am I dividing that weight by two, and getting each strut to support HALF the weight? Sorry if this is obvious...

[tony.latham]

Hey there! Question about the weight rating for the struts: When I get the weight at 50% hatch length, do I get EACH strut to lift about that weight? Or am I dividing that weight by two, and getting each strut to support HALF the weight? Sorry if this is obvious...

Are you using the Excel calculator?

Tony

[Sgt. Paintball]

Just a reminder. The spreadsheet calculator is designed to be utilized when your gas struts are installed in a more vertical position similar to how they are illustrated in the picture. A more horizontal position will require more force and the calculator is not designed for that. Also, the more force required will place increased forces on your hatch, galley, and hinge area, which can lead to failure.

Dan

So does this mean that you could not use the calculator for a square drop? I have a flat hatchback that is a flat 90 degrees vertical square when closed and then opens on a 90-degree angle that is parallel to the ground when in its open position and the gas struts would be attached inside the galley wall and to the inside of the parallel hatch. Can I use this calculator for my build? Let me know if you need pictures to explain?

[reyno2ac]

I know this is an old thread...but I had to create an account just to say thanks! This calculator worked perfectly and my hatch not only opens effortlessly, but holds itself closed!

Thank you!!!

[tony.latham]

I just revisited my old Youtube video, Test Driving the Teardrop Camper Hatch. It's the first lid-lift after installing the gas struts.



It's nothing unique, but the music is great!

Tony

[mariellec]

I am a bit confused about the strut installation, and not sure which numbers are 'negotiable.' My hatch measures 48" and weighs 50 lb. The distance from the hinge pivot point to the galley attachment point is 24" without hitting the counter or the gusset. I am confused about where to find the 'stroke length' since the struts I am finding only give the extended and compressed lengths and I cannot find anywhere that tells me how to compute the stroke length. It seems like it SHOULD be the difference between the two, but I cannot find information to confirm that. So I am stuck, and not sure why it was so easy for everyone else???

[mariellec]

Also, I see some posts with the strut installed with the barrel attached to the galley and some with the barrel attached to the hatch...which way is recommended?

[tony.latham]

...since the struts I am finding only give the extended and compressed lengths and I cannot find anywhere that tells me how to compute the stroke length.

I buy my struts from https://www.mcmaster.com/products/gas-springs/ They've got PDF diagrams of each strut. It'll show the stroke.

As far as the barrel up or down, you want the rod down when the hatch is closed to keep the seals from drying out.



Note the red arrow. If the strut is just below the hinge axle, it won't push up on it when it's closed.





Tony

[mariellec]

Thanks, Tony.

[DesertApprentice]

The standard drawing shows the structs lean in a forward position when fully extended.

Since my hatch is relatively vertical, following the formula, my struts would lean backward when fully open, see the red line in the illustration.
Do all the calculations still apply?
Thanks a lot!

hatch-struts.png (140.92 KiB) Viewed 1845 times

[working on it]

The standard drawing shows the structs lean in a forward position when fully extended.

Since my hatch is relatively vertical, following the formula, my struts would lean backward when fully open, see the red line in the illustration.
Do all the calculations still apply?
Thanks a lot!

hatch-struts.png

* Finally, someone with a vertical (or nearly so) hatch on the forum again; I thought I was the last one to try to use a gas spring on a (home-built) squareback. I started out just lifting the hatch by hand, holding it up with one hand, then inserting prop rods and raising it to a steeper angle overhead. That grew to be a pain over time, so I wanted mechanical help. A linear actuator was my first choice, but wasn't happy with the prices, so I ended up using a gas spring. https://www.tnttt.com/viewtopic.php?f=21&t=61432

* I tried this "Hatch Gas Spring/Strut Calculator", but lost track of the results (due to computer errors), then went off on a tangent, trying other calculators, and ended up using a combination of math and trial & error https://www.tnttt.com/viewtopic.php?f=21&t=69023#p1211649. But, it works, lifting my hatch up to where it floats at 90 degrees (unless the weather's cold, and then it still floats at 45 degrees open), and is real easy to lift the remainder of the way, to my chosen angle (105 or 110 degrees, depending on the ground height, so the hatch is out of the way ...and head-bumping height), using small prop-rod extensions.

* I never tried this calculator after that to see how it would've ended-up, but the initial calculations came up with 125lbs to lift it, but that was for a curved hatch (I presume), since later calcs on another site said 150lbs x 2 gas springs. I ordered two. Once installed, yep 2 x 150lbs springs would've lifted it almost vertically, not to the 90 degree level position I desired (plus, I'm sure that trying to close the hatch overcoming dual 150lb springs would've created another problem, probably with my back or the plywood mounting points deteriorating). As is, a single 150lb spring, mounted nearly in the center of the galley shelf, does what I wanted, and I have the other spring leftover as a spare.


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