Cargo Trailler

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Here is some photos of my bike trailler which I built. I apologize in advance for the blurriness of the images... my camera needs the auto-focus adjusted.



The trailler is built almost completely out of wood. The base is 1/2 inch plywood with 2x2s running the length under each side. The vertical faces are 1/4 inch plywood and the corners are braced with 1x2 strapping. The long sides are fixed and the ends can be slid out so that items longer than the box may be carried. The tongue is another 2x2 which is bolted underneath such that it can be removed and different length tongues installed as necessary. This will allow me to carry 8 foot long pieces of lumber with a 3 foot tongue installed and the ends removed.



Here is a good picture of the whole thing. The wheels are some old BMX wheels which my brother found in the trash. I built an axle by threading a 3/8 inch rod to M9.5x1.0 which runs the full width of the trailler and both wheels are installed on it. This was no easy task, but I think this is a lot stronger than installing a separate blind axle on each wheel. Since I mostly use the trailler to do grocery shopping, and this is almost always done after dark, I installed lots of reflective material and a couple LED blinkers.



The full width threaded axle is placed through holes drilled through the 2x2 side braces and secured with a nut and washer on the back side.



This picture shows the replacable tongue attachment. Three bolts insert through blocks attached to the bottom of the floor. The tongue can be swapped in a matter of minutes with a different length.



Here the trailler is set up for carrying long cargo. The ends have been removed by simply pulling them out, and the extended tongue has been installed. Loads of up to 8 feet long can be accomodated with this set up.



A small load of lumber brought home for other projects.



Motorists give me more room on the road than normal when I carry the barbeque tank down to the filling station. There are eye bolts strategically placed in the cargo compartment to attach bungee cords to secure the load.



The hitch was a blatent copy from DWMurphy's website, who has a designed a neat trailler out of PVC tubing, which incidently inspired me to build my own trailler. Anyway, the hitch is built out of 1x1/8 inch aluminum bar stock, which I bent and drilled to fit my bike. It bolts onto the rack eyelets of the frame on each side of the rear wheel, and to the rack platform itself at the top. This works reasonably well, but I would like a little more side-to-side rigidity. When carrying a heavy load, say over 30 lbs or so, you can feel the hitch wobbling quite a bit. I added reinforcements to the corners, which helped somewhat, but if I build this again, I will probably try some tubular material for the side braces.



Here is a closeup of the actual hitch. The trailler has an eybolt which is free to rotate, allowing the bike to lean, which drops over the bolt shown here. A wingnut secures it all. I added two eyebolts to the hitch so I can attach safety chains. I deemed this necessary after the trailler fell off of the bike on its maiden run, when a poorly designed connection of the rotating eybolt to the trailler tongue broke. Now that I have the chains in place though, I have not needed them. The horizontal platform with the wingnut is built of steel. It originally was just an extension of the aluminum stock, but it was starting to bend after carrying several heavy loads.



This image shows the trailler connected, with safety chains hooked up. The eyebolt is attached to a piece of angle iron bolted to the end of the tongue. The eyebolt is free to rotate, allowing the bike to lean. In fact I once rolled the empty trailler going around a corner too fast, which did a full 360 degree flip, landing on its wheels again. The chains broke during this manouver though, so I am going to try not to do that again.


Other Notes: The stability of this thing is not great when it is empty. It is fine once it is loaded with some weight, but when pulling the trailler empty it bounces around quite a bit. I have accidently rolled the thing twice, although both times I was driving like an idiot around a corner or over speed bumps. I do not plan to do anything about this, except drive a little more carefully. Another problem is that my single piece axle design is showing some limitations on long term durability. It is starting to bend slightly, giving the wheels a slight cant. This is probably a good thing as it will increase the stability, but I am beginning to get concerned about axle breakage. I am probably going to install some steel braces around the wheels to give some support to the blind side of the axle.

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