People bring us all sorts of mechanical things to fix. Shown here is one of two drive units from water bikes someone dumped on us this week. Aside from the fact that it has pedals and has the word "bike" in its name, it's not something we can service extensively in our facility. Sure, we could provide a crank arm to replace the one that got mangled because the owner neglected to keep the bolt tight. We could tighten the other crank arm bolts. We aren't set up to dispose of any amount of rusty, water-contaminated heavy gear oil. We had no service manual. Undoing obvious things only got us a little way into the dark, stinking interior.
When I popped the top on this, a smell like an oily sewer oozed forth. The congealed remains of its lubricating oil sat like filthy pudding at the bottom of the casing. I looked in with a flashlight. It's sparse and simple. The chain makes a 90-degree twist to go around the propeller shaft. It seemed tight enough. Everything was rusty, but what do you want? This thing gets used in water. I topped up the oil from a bottle of it the customer had provided.
This is the view deep into the second drive unit. The chain disappears into the sludge. The chain was a little loose on this one, but I couldn't get the prop off to see if there was any way to tighten it from the lower end. The upper end only fastened in one position as far as I could tell. The prop was secured with two set screws, which came out easily, over the ends of a pin, which would not budge. Because the unit still functioned I did not want to risk disabling it if things went wrong while disassembling it. I added oil and closed the lid.
People bring us any pin and roller chain, no matter what size, because it looks like a bike chain. They come to us for cables for everything from lawn mowers to go karts to ultralight aircraft. Of course we get the garden cart wheels, too. The bike shop was the birthplace of modern mass-produced personal transportation. The idea that we can fix anything is not so far-fetched. If we had a better machine shop we could really get crazy.