An ingenious intermittent mechanism
with its multiple gears, gear racks, and
levers provides smoothness and flexibil-
ity in converting constant rotary motion
into a start-and-stop type of indexing.
It works equally well for high-speed
operations, as fast as 2 seconds per cycle,
including index and dwell, or for slow-
speed assembly functions.
The mechanism minimizes shock
loads and offers more versatility than the
indexing cams and genevas usually
employed to convert rotary motion into
start-stop indexing. The number of sta-
tions (stops) per revolution of the table
can easily be changed, as can the period
of dwell during each stop.
Advantages. This flexibility broadens
the scope of such automatic machine
operations as feeding, sorting, packag-
ing, and weighing that the rotary table
can perform. But the design offers other
• Gears instead of cams make the
mechanism cheaper to manufacture,
because gears are simpler to
• The all-mechanical interlocked sys-
tem achieves an absolute time rela-
tionship between motions.
• Gearing is arranged so that the
machine automatically goes into a
dwell when it is overloaded, prevent-
ing damage during jam-ups.
Its built-in anti-backlash gear system
averts rebound effects, play, and lost
motion during stops.
How it works.
Input from a single
motor drives an eccentric disk and con-
necting rod. In the position shown in the
drawing, the indexing gear and table are
locked by the rack—the planet gear rides
freely across the index gear without
imparting any motion to it. Indexing of
the table to its next position begins when
the control cam simultaneously releases
the locking rack from the index gear and
causes the spring control ring gear to
pivot into mesh with the planet.
This is a planetary gear system con-
taining a stationary ring gear, a driving
planet gear, and a “sun” index gear. As
the crank keeps moving