2-28
2
DRIVE MOTOR 2.12
A drive shaft is used to transmit the rotation of the star to
the output shaft. The drive shaft has crowned external
splines to match the internal splines in the star and output
shaft. This type of drive is used because the star center
line continuously changes during rotation.
As the star orbits, it causes a continuous opening and
closing of the outer ring fluid pockets. Half of these fluid
pockets are subject to fluid pressure, causing star rotation,
and the opposing half are connected to the return line.
When pressure is introduced into the fluid pockets on the
right side of the star ( fig. C156 ) the output rotation will
be counterclockwise. When the fluid pockets on the left
side of the star are pressurized the output shaft rotation
will be clockwise.
C156
C157
To seal the fluid pockets the torque motor incorporates a
rotating roller type seal. ( fig. C157 ) This type of a
rolling seal reduces friction at the star points providing
increased efficiency and reduced component wear.
