Interesting design. They made the hub, web and gear a single item so it is easy to fit and service. However they chose to fabricate it from sheet, except for the hub. The hub is welded to the web, but the ring gear itself is fabricated from multiple layers of sheet, pop riveted together. They may have pop riveted the sheets after stamping them into circles of the right diameter, then cut the gear teeth, then bolted the fabricated ring gear to the web. However I notice that the gear teeth are triangular, not involute, in shape so I doubt they were cut: more likely they were stamped with the teeth included. This enabled them to use cheap stampings for the gear. The downside is that the stampings will be mild steel, so the gear is fairly sure to be dead soft. Also, the triangular teeth of the ring gear will not mesh properly with the involute teeth of the mating pinion, and because the pinion has so few teeth, it may lose the argument. On the positive side, the ring gear itself will still be a whole lot stronger and tougher than the nylon was. The hub should be fine, since it is now welded to the steel web.
With stamped teeth, this gear should have been quite cheap to make. Someone is probably making a huge profit on them.
