CONTROLLED COUPLING HYDRA-MATIC FUNDAMENTALS
(pg 88)

a. With the internal gear held and power applied to the sun gear. As the sun gear turns, the planet pinions also turn on their pins, and walk around inside the internal gear. As the pinions rotate, they turn the pinion carrier in the same direction as the sun gear. The planet carrier turns slower than the sun gear--thus providing gear reduction. jhmCpg88.gif (181088 bytes)
  b. With the sun gear held and power applied to the internal gear. As the internal gear turns, the planet pinions walk around the sun gear. The planet carrier then turns slower than the internal gear--thus providing gear reduction.
NOTE: The reduction ratio in a. is greater than that in b. jhmCpg88.gif (181088 bytes)
5. Reverse is gained with the planet carrier held and power applied to the sun gear. The planet pinions rotate on their pins to act as idlers and transmit power to the internal gear. The internal gear now turns opposite the sun gear at a reduced speed--thus providing reverse rotation of the gear set.
6. A planetary unit provides direct drive when any two of its members are locked together. Neutral is obtained when none of the planetary members is held or locked together --thus making it impossible for the unit to transmit power to the output shaft.

7. From the foregoing, it is apparent that a single planetary unit is actually a two speed transmission.
All that is needed to make it work is a way to prevent rotation of any one of the planetary members
to provide reduction or low speed, and a way to lock any two planetary members together to provide
direct drive or high speed. The units which provide such functions are the following:

To page 89