Moon Buggy 1.2 - construction
I made some further improvements to the sculpture after the 2006 parade. I was moving away from the area, but I had recruited Carl to pilot Moon Buggy in the 2007 race and I wanted it to run better the second time around. Here are the changes I made.
The major problem that had to be addressed was the mounting of the driveshaft. My experience in the 2006 race showed that, one, it is important to have the right spacing between sprockets for chain drives and, two, I didn't have it right. I had assumed that as long as there was less than a half-link of slack in the chain it would be just fine -- so I could just add or remove half-links to make the chains the right length. Wrong! My mounting system for the driveshaft was a mess as well, involving base mount bearings and elbow brackets and way too many screws. The screws tended to come loose and the brackets bent under load. So even if I had gotten the spacing right initially the driveshaft would have shifted under load and let the drive chains slip anyway! I didn't have any trouble with these chains in the parade, but only because I didn't have to go up any hills.
At right is my improved version. The driveshaft isn't mounted in this photo but you can see the improved mounting brackets. Those 'C' brackets are nice and sturdy, and the flange-mount bearings that attach to them don't have any extra room to slide around. I also made the brackets the proper length to minimize the slack in the drive chains and to hold the two halves of the driveshaft nice and straight so that the gearbox could finally turn as freely as it should.
I also made several other fixes, which can be seen at right. I replaced the side supports for the seat with steel tubes. The original supports (furring strips, I think) weren't strong enough and looked kinda junky. The stronger side supports also allowed me to remove the ropes that had helped support the sides of the canvas seatback.
There are two tubes that run from the 2x4 at the bottom of the seat up to the axle. I replaced the mounts for those tubes, both top and bottom. The top mounts were originally another complicated affair with u-bolts and pieces of elbow bracket. Again, it was what I was able to throw together quickly before the race. I replaced them with a single pipe clamp (painted gold in the above photo) and bracket each. The new brackets are much smaller and leave more room for ones' knees when pedaling with the seat raised. I replaced the bottom mounts so that I could move the mount point back behind that bottom 2x4. Moving the mount point back means the seat moves further when raising the seat for water travel, getting the pilot's rear just that little bit further above water.
The last change visible in the above photo is that I took the corners off of the gearbox. This was mostly for esthetic reasons, but it also lightened the sculpture by about half a pound. That's the state I left the sculpture in the summer of 2006.