Worm Gear
A worm gear transmission,
shown in Figure 6-14, is used
in the SCORA-ER 14 to transfer
the rotation of motor 4 to the
rotation of the Z-axis.
The ratio of a worm gear
transmission is defined as:
# teeth on worm gear
# of
starts
on worm shaft
The worm gear used in the
SCORA-ER 14 has 100 teeth
and the shaft has two starts.
Thus, the worm gear
transmission has a ratio of
50:1.
Ball Bearing Spline
The SCORA-ER 14 uses a ball bearing spline, shown in Figure 6-15, to transmit
torque from the worm gear to the Z-axis (slider) shaft, while allowing linear
motion of the axis.
Ball bearing splines are similar
to ball bearing screws in that
they both employ the rolling
contact principle of balls
recirculating in a path between
a shaft (spline) and a matching
nut (sleeve). In a ball bearing
spline, however, the path of the
rolling balls in straight, rather
than helical.
Figure 6-14: Worm Gear Transmission
Figure 6-15: Ball Bearing Spline
SCORA-ER 14 6 - 10 User’s Manual
9603
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