Solar Trailer: Tilt Lock Redesign

by Ben N on August 5, 2021

My first test tow of the trailer went well, but one thing I still wasn’t happy with was the mechanism for locking the angle of the panels. So, it was time for a redesign!

The major thing seemed to be the fact that the tilt lock only had two points of contact. That meant that the locking pin could tip back and forth, allowing the panels to rock a bit when then should otherwise have been in a locked position.

I set to work designing a new tilt lock on the other end of the solar panels. This time, I’d put some thought into it and start designing on paper first. I opened up a drawing program on my computer and laid out a rectangle to represent the size of the metal I had to work with. Then I drew a 3/4″ hole in the middle for the central bolt, with multiple holes around it in an arc.

After a bit of playing around in the drawing software, I realized that I didn’t need a whole circle of holes, just half an arc, as the solar panels only rotate 180 degrees maximum. I also chose to use smaller 3/8th” holes, instead of the 1/2″ I used on the first lock. Since I only needed half a circle, I put the entire design off-center to make more space for the locking holes.

I printed out the drawing on tagboard, cut it out, and put it on the trailer exactly where the metal part would go to make sure everything lined up the way I intended, and that I wouldn’t run into any unexpected issues. Once I was happy with it, I could start working in metal.

I cut a piece of 4.5″ wide steel to 5″ long. Then I taped a print-out to it and marked the centers of the holes with a punch. I then drilled out those centers with a 1/8th” bit on the drill press. After that, it was using larger bits to get up to the 3/8″ holes I had decided on. For the center hole, I used a step bit to get up to the total 3/4″ diameter hole I needed.

After that, I slid the plate over the bolt and end cap and welded it in place. After polishing it up with a flapper disc on the angle grinder, the part looked pretty cool, and it was ready for priming!

No, the arc isn’t perfect, but it’s hard to cut curves with a cut-off disc on an angle-grinder!

Back on the trailer itself, I welded a piece of 3/4″ steel square tube. Drilling a hole through this would make two fixed points of contact to engage the pin.

I reassembled the cap/bolt/plate onto the end of the pipe, slid on the bearing, and got all the parts into place. Then I drilled a hole through the square tube, aligning it with the holes in the rotating plate. Sliding a 3/8″ pin through, the panels locked solidly in place.

One issue that I DID run into was a bad weld. When I welded the bolt to the pipe cap on this end, I only used a very small bead. I did NOT get the plate far enough down to weld directly from the pipe cap to the plate, so that tiny weld was taking all the torque of the rotating panels. As I tested the locking mechanism, I broke that weld by pushing on the panels while they were locked. So, I ended up repairing it by adding some spacers, and then welding the cap to the spacers to the plate. It’s now a very solid weld, but IT’S UGLY!

I double-checked the my original tilt-lock on the other end. On that side, I had gotten the plate all the way down to the pipe cap, and put a couple welds between the two. It was nice and solid, and all torque was transfered to the outer diameter of the pipe cap, rather than just to the 3/4″ bolt. Oh well, live and learn. For the swivels and locks on the OTHER side of the trailer, I’ll make sure to keep this in mind.

But now, I’m pretty happy with the new locking mechanism. It’s solid, works well, and looks pretty good on the side where you see everything happening.

For the next phase of this project, I’m going to get a battery, solar charge controller, and start wiring everything together.

Until then, stay charged up!
-Ben Nelson

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