Time to look at the action by testing the Twin Torsion Axles. Video is a great way to see what’s really happening with the new suspension design, so we’ve mounted a camera!It’s especially nice when we can slow it down or freeze the video frames. It’s a great way to study what’s happening, then know how to make improvements. This is what we did.
First, Some Background
At Mechanical Elements we are always fiddling with new ideas. This time, we decided to build a whole trailer around several new ideas like the Folding Tongue (and it is a very long tongue ), then this new walking beam suspension we call “Twin Torsion Axles”. (More to come.) Through the process of building, we have also posted updates on Building Trailer Frame and information about the Economics of a DIY Project — especially when adding new and creative bits.
With that background in mind, a deeper look at the suspension design (and the motivations for building it) are in this article about Tandem Torsions. You are now the beneficiary of the design, fabrication, experimentation and testing that went into this trailer suspension prototype.
Let’s Watch The Twin Torsion Axles In Video.
Portions of this testing are rather extreme as we don’t normally try to hit curbs with our trailers. Yet, as you watch, the frame bounce is not that harsh considering the size of the step up onto the curb. That is exactly the beauty of this suspension. It is intended to minimize the effects of ground-to-trailer irregularities. And, you can feel it from the drivers seat.
The second thing of note is how active the rocker beam is on the small bumps, and how the frame stays fairly still. Admittedly, some of the video effect is due to the camera mounting, but not all. The camera mounts, sort of, to the frame, but it is only with duct tape, so it does wiggle a little. If the frame was jarring, you would see that in the video.
Comparing to the first test (that had c-clamps holding the axles to the frame in the early test video), this new video shows much more detail. The GoPro is a much better camera for this kind of work. Certainly, the lower, under-the-trailer point of view helps as well. Looking at the suspension from under the trailer just tells so much more about what’s happening.
And, the finishing Powder coat makes it easier to see as we watch the action.
Making the Suspension
To read more and see some about how we made the Teetering Twin Torsion Axles suspension, please see this post on Walking Beam Suspension for Smaller Trailers. It explains some of the rationale, the drivers as well as some of the engineering that goes into the design.
Now, for your own build, blueprints for the rocker beam suspension are available in the plans store in a couple different weight ranges.
For even more information about construction, we did some additional video that will be, or is, posted on this website. They talk about tricks in building it to assure things line up as they should. See the Mechanic’s Post to search.
Twin Torsion Axles Update
Since the time of this second video, deck material was installed, and we’ve taken a few good trips. In the process we found with a trailer load, the twin torsion axles absorb more of the impact. With weight, the rubber in the torsion axles becomes active. The inertia of the load makes the suspension more active. Yeah, it stands to reason, but it’s worth noting anyway. Oh, and the rear wheel doesn’t hang in the air on big bumps (like in the above video) when there is a load.
As with most trailers, tire pressure makes a big difference in ride quality. Tires in the above video are full pressure (bouncy) to demonstrate damping effects of the rocker beam and rubber suspension. On a trip, we experimented with several pressures and found there is a sweet spot that takes away much of the trailer bounce and jostle. Higher pressure bounces more — as we expect, but very low pressure also gave more harshness.
The big takeaway from the test drives is the smoothness and how it handles large and small bumps. That is the goal of the suspension, so this is definitely pleasing. For a lot more info about this trailer and the experimental features, check out the background links above, and The Mechanic’s Post where everything is listed.
Thanks For Watching The Video With Us.