1. Calculate proportions of a standard Brown & Sharps gear tooth of 1½ diametral pitch, making a rough sketch and putting the dimensions on it.

2. Suppose the above tooth to be loaded at the top with 5,000 lbs. If the face be 0 inches, calculate the fiber stress at the pitch line, due to bending.

3. A tooth load of 1,200 lbs. is transmitted between two spur gears of 12-inch and 30-inch diameter, the latter gear making 100 revolutions per minute. Calculate a suitable pitch and face of tooth by the " Lewis " formula.

4. Assuming a ½-inch web on the 12-inch gear, calculate the shearing fiber stress at the outside of a hub 4 inches in diameter.

5. Design elliptical arms for the 30-inch gear, allowing S = 2,200.

6. Design cross-shaped arms for 30-inch gear.

7. - Calculate the dimensions shown in formulas 70 to 82 in-for a pair of bevel gears of 20 and 60 teeth respectively, 2 al pitch, and 4-inch face. (The use of logarithmic tables he calculation much easier than with the natural functions).

Fig. 47.

8. A worm wheel has 40 teeth, 3 diametral pitch, and double thread. Calculate (a) its lead; (b) its pitch diameter.