3. What is the property of matter that allows the belt to turn the pulley?
4. What kind of motion is illustrated in a rotating pulley?
5. Explain how Babbitt metal reduces friction.
7. Why is it necessary to have shafting of different diameters?
8. Explain two forces at work on a rotating shaft.
9. Is leather belting stronger than canvas?
10. Why is a pulley "crowned"?
11. Explain the difference between a pulley and a gear.
12. When is transmission by gearing preferred to transmission by pulley and belt?
14. Explain the meaning of the following terms used in gearing: diametral pitch, circular pitch, diameter of pitch circle, whole diameter, bottom diameter, number of teeth, working depth of tooth, velocity of gear, distance between centers of teeth, whole depth of tooth.
1. One gear has 200 teeth and another 50 teeth. What is the ratio of the diameters of their pitch circles?
2. Two gears have pitch circles of 85 in. and 17 in. in diameter respectively. What is the ratio of their speeds? What is the ratio between the number of teeth in their gears?
3. A 48-tooth gear drives a 120-tooth gear. What is the ratio of their speeds?
4. Two shafts are connected by gears. One turns 55 times a minute, and the other turns 11 times a minute. If the smaller gear has 32 teeth, how many teeth has the larger gear?
5. Three gears of a train have 69, 30, and 74 teeth respectively. If the 69-toothed gear makes 100 R. P. M., how many R. P. M. will the 74-toothed gear make? Figure the result and make a sketch of the gears, showing by arrows the direction in which each turns.
6. A train of gears is made up of 6 gears having teeth as follows: 46, 60, 32, 72, 56, and 48. While the first gear in the train makes 10 turns, how many turns will the last gear make?
7. What two gears will give a ratio of speeds so that the driver will make 13/14 as many turns as the follower; in other words, while the driver makes 13 turns the follower will make 14?
8. A horse used for moving a house walks around in a 12-ft. circle pulling 800 lbs. on a capstan bar. If the drum of the capstan is 24 in. in diameter, how much pull will the rope exert on the house?