Mono-leaf experiment

[eggsalad]

My trailer...



...was originally a PWC trailer. I did some googling around, and I find that most PWC weigh between 600-800 lbs.

The camper I built on the trailer weighs nowhere near that. By my best estimate, the parts I added weigh no more than 300 lbs.

The axle on the trailer is unknown as to the weight rating, same with the 2-leaf slipper springs. I will say that the lightest-duty 2-leaf, slipper springs I can find online are rated at 475 lbs per spring. Mine may be rated for more, no way to know.

Anyhow, when my camper was done, I bounced my 200+ lb. body on it, and the springs wouldn't even budge. The only bounce was in the tire itself.

I figured that was gonna make for a very bouncy trailer going down the road.

Had some free time today, so I pulled one side of the axle off the spring. (I love living in the desert, where even 28-year old hardware isn't rusted solid!) I took out the "helper" leaf and set the trailer back on the axle. Now I can actually get some movement on the spring when I bounce my big butt on it! From what I read here and elsewhere, that will make the trailer bounce less, making for a better pull.

But you folks know WAY more than I do. Is there any downside to running a single leaf? Should I put things back the way they came, or take the other side down to a single leaf, then clean and paint the mono-leaves and reassemble?

What would YOU do?

Thanks,
eggsalad

[pchast]

I've got to ask how you know it doesn't move? Did you have someone
with a yard stick measure the difference? I'd want to have a helper
do that on both sides before a decision. I'd also want to get under
the trailer and try to determine where its bending and check wear.

Is this just going to be a paved road trailer?
Just throwing out thoughts at this point...

[eggsalad]

Well, no, I could actually see the spring flex as I bounced on the side with the single spring. On the other side, the spring didn't flex at all.

The worst roads the trailer will see is graded gravel from the campground entrance to the site. Help me understand how it is relevant.

What is the downside of being under-sprung?

[pchast]

I can't tell how much movement there is by observation without a measure myself. I am neither a mechanic nor a materials engineer....

Your situation is different from a situation I remember. You have one uniform spring instead of a stack now.

Under sprung would have a greater chance to be affected by balance, loading and fatigue. Its a problem of relative use and only experience will tell. I would assume you are ok if you can maintain the light weight. You probably should verify the weight when done and loaded for use.

[48Rob]

Egg,

Your plan to reduce the amount of leaves to get the springs closer to the actual weight they will carry is good.
A trailer that has springs rated to carry 3000 pounds will bounce terribly if the loaded trailer they carry weighs only 500 pounds.

The issue is than in order to be safe/not worry about breaking the single spring, you need to have real numbers to start with...

If the spring pack is rated at x pounds, and you remove a leaf, leaving one, what is the new (x) rating?
What is the close estimated finished weight of the trailer it/they will carry, and how close it to the max rating of the reduced capacity springs?

More research is needed, or it is just guessing, which could be dangerous, both to your trailer and others on the road.
A spring shop may be able to help.
Is there anything stamped into the axle tube, etc?

Rob

[eggsalad]

Egg,

Your plan to reduce the amount of leaves to get the springs closer to the actual weight they will carry is good.
A trailer that has springs rated to carry 3000 pounds will bounce terribly if the loaded trailer they carry weighs only 500 pounds.

The issue is than in order to be safe/not worry about breaking the single spring, you need to have real numbers to start with...

If the spring pack is rated at x pounds, and you remove a leaf, leaving one, what is the new (x) rating?
What is the close estimated finished weight of the trailer it/they will carry, and how close it to the max rating of the reduced capacity springs?

More research is needed, or it is just guessing, which could be dangerous, both to your trailer and others on the road.
A spring shop may be able to help.
Is there anything stamped into the axle tube, etc?

Rob

Food for thought there, Rob. As the trailer is 28 years old, I really don't have much information on it. There is a decal on the frame stating that the entire axle is a product of the Bearing Buddy company. Best guess is that, at some point, they sold entire axle/hub assemblies to trailer builders. An email to the Bearing Buddy company did not get a response.

Your point about breaking a mono-leaf spring is very valid, and something I'd not taken into consideration.

Short of buying a new axle and new springs (and at that point, I could dang near buy a whole new trailer) there's no way I can get detailed information. I certainly don't want to endanger myself or others. Thanks for your input.

[Kody]

Single leaf springs have both good and bad points. A single leaf spring should be tapered in thickness and be a specific curve. For a light load they work well. The obvious problem is if they break. They always break following Murphy's law, at the worst possible time and at the worst place on the road. Once they break, you are stuck there until a new one can be obtained. You can do a "jury" rig and jamb a piece of wood between the axle and the trailer and lower the tire pressure about 10 or 15 pounds to help stop the jarring. If the spring has come from a boat trailer, be careful as the spring can snap at any time. This is caused by the spring being hot dipped galvanized (is it galvanized?). This hot dip galvanizing can destroy the original temper of the spring leaf. They can also suffer from fatigue. For this reason, a spring for a trailer (not being a boat trailer) should never be hot dipped galvanized. Slipper springs are bad news and should not be employed as springs for a teardrop. However, I have seen hot dipped galvanized springs as a single leaf, work extremely well without failing. The quality of the finished spring depends on the type of steel and how carefully it is manufactured when it is forged and heat treated. Springs are not all made from the same type of steel. I worked as maintenance engineer and draftsman for a world renown spring manufacture here in Australia. In my judgement, you would be far better off to install springs having at least two leaves or even three. The spring should be matched to the total load of the trailer and should be fitted with shackles at the trailing end. The shackles will raise the height of the frame about 3 inches or a little more above the ground and this may have to be taken into consideration. (More specifically, about 3 inches measured at the axle.) You can get a reasonably good idea of the springs ability by measuring the distance (height) of the trailer frame above the ground where the axle is. Then, load the trailer frame at that point with a known weight. A bag of cement works well and use two bags if possible. Load one bag on the frame above the axle and measure how far the trailer has dropped. Load the second bag on top of the first bag and measure the height again. If the frame dropped say 1 1/2" with the first bag, it should drop another 1 1/2 " with the second bag. However, the spring rate may not be constant because of the spring design but this will give you some idea of what the spring is doing. A more accurate result can be found by loading more bags of cement until you load the equivalent weight of half the finished van weight. Measuring the height of the frame each time will enable you to reasonably work out the spring rate. That is, the deflection verses load and this will plot as a specific curve.
You will need to note down the weight of each bag of cement and apply this to your calculations.
Hope this helps and doesn't confuse you.

Kody

[eggsalad]

Know what? All things considered, sometimes a man has to admit he doesn't know Jack. When it comes to springs, I'm just going to have to admit that.

Until such time as I choose to purchase a proper spring for this application, I'm going to stick with the known quantity. I'll just refinish and rebuild the springs as they came. Sometimes the best thing to do is nothing!

thanks for all the advice,

eggsalad