372 APPLIED MECHANICS 
Fig. 572. The teeth of the wheels in this design are wedge-shaped, and 
the links have wedge-shaped projections which gear with the teeth, as 
shown. When the chain 
’ is new one edge of a wedge 
on one link and the op- 
posite edge of the adjacent 
wedge on the next link 
bear on the front of one 
tooth and on the back 
of the next respectively, 
but when the pitch of 
the chain has increased 
through wear, the contact 
is as shown in Fig. 572. 
With this chain there is 
no rubbing of the links 
on the faces of the teeth 
as they come into or go 
out of gear. Fig. 572, 
Exercises XXII. 
1. A belt 4 inch thick drives a pulley 15 inches diameter, which makes 800 
revolutions per minute. Find the speed of the belt in feet per minute, (a) 
neglecting the thickness of the belt, (b) taking the thickness of the belt into 
account. Express the difference between the two results as a percentage of 
the second. 
2. Two pulleys are connected by a belt. The sum of the diameters of the 
pulleys is 36°5 inches, and while the one makes 50 revolutions the other makes 
200 revolutions. Find the diameters of the pulleys. . 
3. A train of pulleys is shown in Fig. 573. B and C are fixed on one shaft, 
and D and KE are fixed on another 
shaft. The diameters of the pul- 
leys, in inches, are, A=30, B=15, 
C=50, D=16, E= 25, and F=12, 
A runs at 80 revolutions per 
minute. Find the speed of F, 
(a) neglecting thickness of belts, Fig. 573. 
(6) taking thickness of belts as 
#8; inch. Express the difference between the answers (a) and (b) as a percentage 
of answer (b). 
4. A shaft running at 200 revolutions per minute carries a pulley 50 inches 
diameter, which drives a dynamo at 1200 revolutions per minute by means of a 
belt 4 inch thick. Allowing for the thickness of the belt and a slip of 4 per 
cent., determine the diameter of the pulley on the dynamo. 
5. A pulley 36 inches diameter is connected to a pulley 18 inches diameter 
by a crossed belt. The distance between the axes of the pulleys is 48 inches. 
Calculate the length of the belt in inches, (a) by the exact formula, (b) by the 
approximate formula (Art. 308). 
6. Same as preceding exercise, except that the belt is an open one. 
7. A pulley 50 inches diameter is connected to a pulley 10 inches diameter 
by an open belt. The distance between the axes of the pulleys is 45 inches. 
Calculate the length of the belt in inches, (a) by the exact formula, (6) by the 
approximate formula (Art. 308). Express the difference between the two results 
as a percentage of the first. What will the results be for a crossed belt ? 
8. Referring to the stepped pulleys shown in Fig. 556, p. 364, D,=36 inches, 
d,=12 inches, D,=d,., ds=4D3, c=48 inches. The belt is an open one, Find 
D,, Ds, and ds, and also the length of the belt 2, all in inches. 
9. Referring to Fig. 556, p. 364. The shaft A runs at a constant speed of 
