Gas lift struts for trailer question

[[email protected]]

I have an old (1972?)semi-clamshell type trailer. When open, 4 gas struts hold the "lid" up. Two look like original equipment from Germany and two from an, apparently defunct, company (Colmar Gas Springs) in Pennsylvania. In cold weather the hatch won't stay open. Any idea as to how to determine the lifting force necessary for new struts? I didn't see that number on the existing struts but it may be there. I was able to get the P/N off the American struts, thought that's all I would need and stopped looking. I found out today they were a two person company and the phone number doesn't work. The trailer is now 300 miles away in winter storage so I don't have ready access to look for more numbers. No rush, the spring ridge season is a long way off.

[Bob Kuykendall]

McMaster-Carr has a good selection of gas springs of the most common sizes:

htp://www.mcmaster.com

To estimate the force required to hold the trailer top open, the easiest way is to just use bathroom scales or similar to see how much force is required when the trailer is fully open. But that only works well when the geometry is fairly straightforward.

Thanks, Bob K.

[Steve Koerner]

Look for a number with 'N' after it, for Newtons. 1 Newton = 0.2248 pounds force.

[[email protected]]

Thanks guys. It should be pretty straight forward once I have a closer look at the struts to get the numbers. That McMaster site looks like a great resource.

[Dave Nadler]

On Monday, December 9, 2013 7:52:49 PM UTC-5, Bob Kuykendall wrote:
> To estimate the force required to hold the trailer top open,
> the easiest way is to just use bathroom scales or similar
> to see how much force is required when the trailer is fully
> open.

Right - Prop the trailer open using a 2x4 cut to length,
propped at the spring attach, angled in the direction of
the spring, against a scale held in the proper orientation.
You'll need a helper to prevent dropping the trailer
top when you do this and a 2nd 2x4 for the opposite side...

We're waiting for the video.
DON'T DROP THE TRAILER TOP !

Have fun, See ya, Dave

[Dave Nadler]

PS: Detach the defunct springs to get a correct reading
PPS: You may not need to lift the top all the way up
iff the geometry is such that the spring load is constant,
but you do need the spring length with trailer open...

[[email protected]]

On Monday, December 9, 2013 3:46:42 PM UTC-5, wrote:
> I have an old (1972?)semi-clamshell type trailer. When open, 4 gas struts hold the "lid" up. Two look like original equipment from Germany and two from an, apparently defunct, company (Colmar Gas Springs) in Pennsylvania. In cold weather the hatch won't stay open. Any idea as to how to determine the lifting force necessary for new struts? I didn't see that number on the existing struts but it may be there. I was able to get the P/N off the American struts, thought that's all I would need and stopped looking. I found out today they were a two person company and the phone number doesn't work. The trailer is now 300 miles away in winter storage so I don't have ready access to look for more numbers. No rush, the spring ridge season is a long way off.

Grainger carries Bansbach Easylift gas springs. I replaced gas springs on my homebuilt trailer because they kept bending when trying to close the top.. Called Bansbach in Melbourne, FL and found out they only sold to business resellers i.e. Grainger et al and a minimum order from them was 1k. But, spent about a half hour on the phone with one of their engineers discussing the issues I was having. He recommended several options for replacement gas springs to replace the new ones I purchased from another company, that company was much less than helpful. As a note, Grainger was not very helpful either when I went to the local store with the damaged gas springs. But they do have a lot of choices they can order for you.

Was toying with linear actuators (electro-mechanical) but after some comments here, gave that idea up. Will get some cables made for both sides of the lift mechanism to limit the extension of the gas springs. Worked this weekend. And put the top down slowly.

Bansbach website has an page where you input measurements and it provides the gas spring required. but you need to do a lot of measuring and know the newtons/lbs required.

Still like the linear actuator idea though

r/Jim
N9XL/H-201B

[son_of_flubber]

On Tuesday, December 10, 2013 8:53:58 AM UTC-5, Dave Nadler wrote:

> You'll need a helper to prevent dropping the trailer
>
> top when you do this and a 2nd 2x4 for the opposite side...

> DON'T DROP THE TRAILER TOP !

Having replaced the struts on my trailer just last summer by myself with no maiming, I have relevant experience.

Several local wags suggested suspending the trailer lid from an overhead beam in the hanger and I added a "ratcheting lever winch" (aka a-come-along) to the mix. The raised lid resembles a guillotine or maybe a giant chop saw, especially since you will need to put precious bodily parts on the block repeatedly.

The 2X4 is a good way to measure the force, but not needing to do that I used a 2' X 4' piece of 3/4 plywood (Advantech actually) with one end cut to the matching angle. One end of the plywood fit in a rib of the corroborated floor and the other end fit in the U-lip edge of the top. Tapping the plywood with a mallet fore-aft I was able to make very precise adjustments on the height of the lid and this was needed to align the strut mounting bolts precisely. The suspending rope had some stretch, so the plywood and the rope shared the load.

It was nice to have a totally foolproof and redundant way to hold up the lid because it could easily amputate something, possibly your head. Before I thought of the plywood "wedge", I struggled unsuccessfully for an hour to align the bolt holes of the strut.

Another advantage of doing this under cover is that you don't have to worry about the wind while the lid is raised and precarious. Also be sure to replace the struts in pairs and keep the good old one for an emergency spare.