BELT, ROPE, AND CHAIN GEARING 367 
of that part of the belt which is advancing towards the pulley by means 
of a fork, which should be as close to the fast and loose pulleys as 
ible. 
Examples of the use of fast and loose pulleys are shown in Figs. 562 
and 563. ‘These arrangements of belt gearing are very frequently found 
in connection with machine tools. i = 
AB is a driving shaft, and CD A E B 
a counter-shaft. E is a broad 
pulley fixed on AB. L, and L, 
are loose pulleys, and F is a fast 
pulley. The machine is driven H K 
by a belt from the stepped pul- ' 
ley G. An open belt H anda ™M | N= 
crossed helt K pass from the 
pulley E to the pulleys on CD, © D || 
as shown. MN isa rod carrying C Ey axe =A 
forks, by means of which. the 
belts H and K may be shifted Fie 562. Fi. 563. 
simultaneously. When the belts are in the position shown, CD is at rest. 
If MN be moved to the right K will remain on L,, H will embrace F, and 
CD will rotate in the same direction as AB. By shifting the belts to the 
left of the position shown, CD is made to rotate in the opposite direction 
to AB. A modification of the arrangement just described, to give a quick 
return motion, is shown in Fig. 563. The latter arrangement may be 
used to get fast or slow motion as desired, in the same direction, by having 
both belts open or both crossed. 
In the arrangements of fast and loose pulleys shown in Figs. 562 and 
563, the loose pulleys have a width not less than twice the width of 
the belt. By using a suitable form of belt-shifting gear the loose pulleys 
may be of the ordinary width, and then not only is space saved on the 
shaft, but only one belt has to be shifted at a time. Fig. 564 shows 
such an arrangement. L, and L, are loose pulleys, while F, and F, are 
fast pulleys. The belt forks are attached 
to levers A,B,, and A,B, mounted on fixed 
pinsat C, andC,. These levers are provided 
with projecting pins at B, and B,, which enter 
into slots in a dise DE, keyed to a spindle F. 
The lower parts of the slots in DE are con- 
centric with F, and the upper parts are more 
or less radial. In the position shown, both 
belts are on the loose pulleys. If the disc 
DE be turned in the direction of the arrow H 
the lever A,B, remains at rest, because the 
pin at B, remains in that part of the slot 
which is concentric with F, but the pin at B, 
will be pushed to the right by the upper part 
of the right-hand slot, and the belt which was 
on L, will be shifted to F,. By moving DE 
from the position shown in the direction of 
the arrow K the lever A,B, will remain at rest, and the lever A,B, will — 
be moved so as to shift lt which was on L, to F). 
Ue ee ee ee a ee” 
ee eee ee, 
Fig. 564. 
ee ee ee eee 
