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M E C H A N I C A L
P R I N C I P L E S
19
of four bearing shoes held against the feed roll
shaft by compression springs.
The card also passes two sets of brushes and con-
tact rolls. The brush assemblies are identical ex-
cept for minor constructional differences; each
consists of 80 individual brushes mounted in a
brush holder so that they are insulated from each
other.
The contact rolls are made of beryllium
copper and are geared to turn at a higher speed
than the feed rolls to provide a wiping action by
the card.
Index and Cycles
In explaining machine operations it is necessary
to make reference to one operation in terms of
Figure 18. Punch Feed K n i f e Drive
another. By using an index for a common refer-
ence point this becomes possible. The index gear
Feeding Mechanisms
serves as the common reference for all machine
The purpose of the feed knives is to feed one
operations. One complete revolution of the index
card through the throat into the first set of feed
gear is called one cycle. If the punch clutch is en-
rolls for each revolution of the punch clutch. The
gaged, a card would move from the first set of
feed rolls rhen carry the card past the brush sta-
brushes to a corresponding posirion at the die (or
tions and punching station to the stacker.
The
from the die to the second set of brushes) during
knives are driven back and forth by gear sectors
one revolution
of
the index.
For convenience in
which mesh with the feed knife racks. The gear
measurement one cycle is divided into units called
sectors are pinned to a shaft which oscillates under
cycle poifzts.
The most logical unit of division is
the control of a complementary cam and follower
the distance between successive punching positions
mounted on the punch clutch shaft (Figure 18).
on the card.
Therefore the distance from the
9
When a card is fed from the magazine, it is fed
punching position to the 8 punching position in
between the first pair of feed rolls. The feed rolls
one card represents one cycle point, while the dis-
operate intermittently, hence rhey will be station-
tance from the
9
punching posirion in one card to
ary during a portion of the time a card is being fed
the
9
punching position in the following card is
between them. The feed knife carries a card up
one cycle.
to the first feed rolls while the feed rolls are sta-
There are 12 punching positions on the card.
rionary.
T o insure that the first feed rolls will
Each punching position is
j/4
inch from the next,
pick up the card, the knife buckles the card slight-
therefore, for each cycle point the card moves
'/4
ly just before the feed rolls start turning.
inch on its path rhrough the machine.
Since the
As indicated in Figure 16, the card passes
card is 3
'/4
inches wide, it requires 13 cycle points
through four sets of feed rolls on its way to
he
to advance a card past any given point.
In this
stacker. The upper feed rolls are mounted in fixed
machine there is
'/4
inch between cards, therefore,
bearings while the lower feed rolls are provided
the cycle consists of 14 cycle points. The teeth on
with
pivoted bearings to allow separation of the
the index gear are used for further subdivisions.
rolls when a card is fed between them. Feed roll
Thus a timing given as 14.1 indicates one tooth
tension is provided by a pressure bracket consisting
past the
14
index mark.
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