Holy Axle Overload Batman!?

[Gyro Gearloose]

Pat,
The front spring and axle is moving toward the frame not away from the frame under heavy braking. Since GDRV has moved to 4400 lb axles and springs, I will keep my current setup and will add the Timbren 600lb units above the axles. This will act as bump stops which is needed on all trailers and can also be used to prevent overtravel of the equalizer and lifting of the front axle. Another thought is a modified equalizer with bump stops to prevent over rotation. I don't think this issue is too difficult to correct.

got ya, I was speaking more toward the rear spring. I do agree bump stops would be a good thing.

Do you know the free length of what you are going to install? Do you have any dimensions of the hangers you have on yours?

[Gyro Gearloose]

Another option for trailer axles.

https://www.autoflexsuspensions.com/trailer-flex

Well it looks like they put it on a good trailer. I looked at this setup awhile back, I think someone posted a pic of the setup from an article. I did read about this setup and it looks really heavy duty, I personally had a couple of concerns. The setup looks very heavy and it also has what seems to be an inherent issue (in my mind) that most of the designs that use the full trailer axle have, no articulation side to side. On their web site they tout not using u-bolts and how the axles are welded to their setup, this means the setup it pretty much tied together side to side, unless I'm missing something.

[Cate&Rob]

Hi Pat,

Back when we were trying to level out the trailers side-to-side I was thinking that air bags with different pressures side-to-side could do this. I hadn’t even considered how this might help during axle lift when braking.

A question raised by Steve (Steven@147) has also been puzzling me. Why link the two axles through the equalizer? I have looked for the engineering rationale for this without finding anything. Why not just have two independent leaf spring suspensions with trailing shackles .

Rob

[Country Campers]

I believe the equalizer is there for the range of motion for both axels. If the axels were mounted separate and both ends where installed into hangers, then when the spring would need to compress and get longer it would not be able to. If we were to mount separate we would need one end to have a swing shackle to allow the articulation of the suspension ( not sure if that is the right word or not but it is a big one).
I think this mod would be a huge benefit to stopping the front axel lift when braking.

So engineers , do we have room to eliminate the equalizer and add a swing shackle? Something similar to a rear leaf spring on a vehicle.

Brian

[Gyro Gearloose]

Hi Pat,

Back when we were trying to level out the trailers side-to-side I was thinking that air bags with different pressures side-to-side could do this. I hadn’t even considered how this might help during axle lift when braking.

A question raised by Steve (Steven@147) has also been puzzling me. Why link the two axles through the equalizer? I have looked for the engineering rationale for this without finding anything. Why not just have two independent leaf spring suspensions with trailing shackles .

Rob

Rob, I'll go out on a limb here and the short answer is just what the name implies Equalizer, I think? When I was doing the Shackle Length eval for you, is when I think I understood the Equalizer concept. I think in one of our emails I attempted to explain it.

Note: Please bare with me as I babel my way through this. As I tried to write this it became more and more difficult to try to explain. I hope this makes sense and I am not off base. I could do a PDF if needed.

I think where the Equalize comes into play in one of the best examples is, nose-up or nose-down. In this case I think the axles still get pretty much equal load. With separated springs the and a nose up condition, the rear axle would get more load. Now your rear hangers would get more load and so on.

I thing the shackles are either pushing or pulling with near the same amount of force equalizing the load on the springs. One of the things that came clear and I think I alluded to it in my first PDF in this thread is how the spring lifted off the ground changes how it works as a spring because of the Equalizer.

Trying to picture this in a PDF I think I just realized how to explain how the Equalizer works! Think of the Equalizer as a Pulley (cable Sheave). Then the Shackles as a cable that is running under the Pulley to each Spring Eye. The Center/Rotating point of the pulley is the hanger attachment point. So whatever force is being applied to one spring eye is transfer through cable to the other spring eye. Hmmm I like it.... does it make sense? Not exact, just and example of how to visualize.

So now the spring.... The spring is being acted upon in 2 ways. 1. Vertical-from weight, changing the Loaded Arch , as you typically expect a leaf spring to work 2. Horizontal-from being pulled on by the shackle and the Equalizer and the other spring. The more pull on the spring eye lengthens the spring, decreasing the Loaded Arch.

Example: If you have a 3K 3" Unloaded Arch 25.25 eye2eye Spring that compresses 1" @ 3K (2" Loaded Arch & 25.75" eye2eye) here is what I think happens with Vertical or Horizontal force applied. In theory (my mind) if a vertical 3K lbs applied, Loaded Arch=2" eye2eye=25.75 as above. Horizontal Load of 3K (pulling on the eyes) would stretch the spring eye2eye length to 25.75" and would still result in a 2" Loaded Arch. So the Horizontal example is where I think the Equalizer forces take place for the most part.

The spring Horizontal/Equalizer effect is one of the reasons the tire lifts off the ground in the video. It stretches the spring and reduces the Loaded Arch lifting the tire more.

Are you confused yet?

[Gyro Gearloose]

I believe the equalizer is there for the range of motion for both axels. If the axels were mounted separate and both ends where installed into hangers, then when the spring would need to compress and get longer it would not be able to. If we were to mount separate we would need one end to have a swing shackle to allow the articulation of the suspension ( not sure if that is the right word or not but it is a big one).
I think this mod would be a huge benefit to stopping the front axel lift when braking.

So engineers , do we have room to eliminate the equalizer and add a swing shackle? Something similar to a rear leaf spring on a vehicle.

Brian

I saw this on lippert site an made me think about spring attached directly to equalizer and shackles at the back. I think this would be similar to the center axle on a triple axle setup? Would need to look at forces.
https://store.lci1.com/equalizer-105-w-nyon-bushing

I was also thinking something like the Lippert Banana Shackles and a high pressure Mono-Tube Shock from the Shackle to the center of the spring to dampen and counteract the action. I did some stuff like that when I was experimenting with my Land Cruiser suspension.

[MidwestCamper]

got ya, I was speaking more toward the rear spring. I do agree bump stops would be a good thing.

Do you know the free length of what you are going to install? Do you have any dimensions of the hangers you have on yours?

Pat,
I have not taken any measurements and will wait until spring. Since I did the spring blocks and MORryde installation, wet bolts, etc, I have been writing about the need to have these to prevent spring overtravel and resultant yielding. These should be standard on all trailers IMO.

[MidwestCamper]

Hi Pat,

Back when we were trying to level out the trailers side-to-side I was thinking that air bags with different pressures side-to-side could do this. I hadn’t even considered how this might help during axle lift when braking.

A question raised by Steve (Steven@147) has also been puzzling me. Why link the two axles through the equalizer? I have looked for the engineering rationale for this without finding anything. Why not just have two independent leaf spring suspensions with trailing shackles .

Rob

Rob,
This system could be used to level side to side. I think the thought behind the equalizer is to articulate between axles to transfer some support to the apposing axle during rough road encounters. This air bag design would not cause a traction issue since the rotational forces (brake torque) is apposed by a solid anchor point. A slipper type unit or a full independent suspension would prevent anything like we see on the equalizer equipped systems.

[Cate&Rob]

Rob, I'll go out on a limb here and the short answer is just what the name implies Equalizer . . . Are you confused yet?

Hi Pat (and others)

I get that the “equalizer” transfers vertical load from the lifted axle spring to the other spring because it allows one spring eye of the lifted spring to move up while pushing down on the eye of the adjacent spring. I think the shackle plate connections remove almost all horizontal load transfer from spring extension.

Watching the video of how trailer braking lifts the front axle might be a whole new level of “understanding” that the equalizer suspension designer never contemplated.

Rob

[MidwestCamper]

A simple ladder bar on the front axle may also help this condition. When observing the LCI video, the front section of the front spring is excessively bent showing rotation there as well. A simple and cheap fix is to install the Roadmaster slipper spring kit. Or the MORryde IS for those with deep pockets. Too bad there are no bolt on kits for less than 5K axles.