One of the basic relationships for a gear is the number of teeth, the diameter, and the rotary velocity of gears. Figure 2-5 shows the ends of two shafts A and B connected by 2 gears of 24 and 48 teeth respectively. Notice that the larger gear will make only one-half turn while the smaller makes a complete turn. The gear that is closer to the source of power is called the driver , and the gear that receives power from the driver is called the driven gear . A gear train may have several drivers and several driven gears.
C turns once clockwise.
Hence gear B does not change the speed of C from what it would have been if geared directly to gear A, but it changes its direction from counterclockwise to clockwise. The velocity ratio of the first and last gears in a train of simple gears dose not changed by putting any number of gears between them. Figure 2-7 shows compound gears in which two gears are on the middle shaft. The number of teeth on each gear is given in the figure. Given these numbers, if gear A rotates at 100 r.p.m.