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Transcript

These two wheels are mounted on separate axles and supported by a frame. So that they can revolve freely at different speeds. Let's fasten a spork. On the inner end of each axle. So that by turning the spokes. We can turn each wheel separately. With a bar or cross piece. We can turn both wheels in the same direction. At the same rate of speed. Let's get something to hold this bar in place so that it will press against the spose. Notice that this support is not locked to the axle, it turns freely. Now we can spin the wheels by rotating the support. This is fine as long as both wheels are able to turn at the same speed, but let's see what happens when we go around the corner. With this arrangement, we cannot drive one wheel faster than the other. And if we stop one wheel? The other wheel won't budge. Let's put this bar on a pivot. So that it can swing in either direction. Now. The bar can still turn both wheels at the same speed. And because it pivots. It lets one wheel turn. Even when the other is stopped. But if turned too far, the bar will swing around until it won't drive the spokes that turn either wheel. We need another crossbar and more spokes to carry on the job. When we stop one wheel. The crossbars will continue to push the spokes of the free wheel around. As long as both wheels are free to turn. The bars do not swing on their pivot. And the wheels move at the same speed. Now we have the working principles of a differential. To adapt the model for use in an automobile. We will have to make a few changes. In order to reduce the jerky action caused by wide spaces between the spokes. We will put in more spokes. Further, filling in the spaces between the spokes gives steadier, more continuous action. And changing the shape gives firm constant contact. Now we can make the gears thicker and stronger and we have differential gears. The edges are cut so that they will fit together more smoothly and silently, and another gear is added to share the work of driving the axles. The principle is the same. In order to turn the support and drive the wheels, we can fasten a large gear here connected by a smaller gear. To a source of power. Notice that the power is connected to the differential at the center line. We can make our model more compact by moving the.