Human Electric Trike Thesis

Design of an electrically assisted human powered trike

Archive for November 10th, 2006

11/10 Update

Posted by Bob Dold on Friday, November 10, 2006 8:26 PM

Fabrication is nearly complete, actually was able to ride the trike for the first time the other day using pedal power, still need to work out some chain routing issues, but for the most part it worked well. Based on my very short test ride a few things became apparent – #1, I am very happy with the suspension, it really smooths out the bumps and makes it more comfortable to ride. #2, the steering realy scrubs when pushed into a tight turn so I need to double check the geometry to check if the Ackerman compensation is correct. #3, running the motor unloaded produces a lot of noise, hopefully this will dissipate a little when it is hooked up to the drivetrain.

I tried instaling the handlebars from my Sun tadpole, but they are too short as seen in the pictures, I ordered some 7/8 aluminum tubing and hope to bend up some longer ones using an electrical conduit bender.

The drawings I got my disk brake mount locations from was incorrect so I had to space the mounts out about a 1/4 inch using a stack of washers as shown:

 

As with any prototype there are a number of things that have popped up that I would change if I had to do it over again, but that is all part of the learning process. Here are a few of them:

Adhesive bonding of aluminum tubes work well in some cases and not so well in others. The tubes I bought were not very round, so even though the blocks they go into were made very accurately, the tubes themselves were not round, causing uneven gaps which the Loctite adhesive did not like. On the block that holds the boom tube to the fram this was especially apparent and I had to reglue twice. It still is not a good joint and I had to rivet it to back up the glue bond. To fix this I would make the block longer to add more glue surface area, force the tube round using a mandrel, and add some sort of backup fastening system.

If this trike were to be manufactured, it would have to go to a welded contruction, the bonded construction requires too many machined components and requires precise tubing for the bonded joints. The welded construction would also produce a lighter weight frame by eliminating most of the blocks.

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