extends through the piston and out through both ends
of the cylinder. One or both ends of the piston rod
may be attached to a mechanism to be actuated. In
either case, the cylinder provides equal areas on each
side of the piston so that the amount of fluid and force
required to move the piston a certain distance in one
direction is exactly the same as the amount required to
move it an equal distance in the opposite direction.
Actuators are designed for a particular type of
installation. For example, internal locking cylinders
are used on some bomb bay door installations, while
cushioned types are used where it is necessary to slow
the extension or retraction of landing gears.
Mechanical-Lock Actuating Cylinder
In many installations it is necessary to lock an
actuating cylinder in a specified position. This may
be for safety or operational requirements of the unit.
The different designs of lock cylinders vary between
manufacturers, but they are usually of the ball-lock or
finger-lock type. At times, indicating devices are also
incorporated along with the lock feature of the
cylinders.
BALL-LOCK ACTUATOR. —The cylinder
shown in figure 8-3 is a single-action, ball-lock
Figure 8-3.—Cutaway of a single-action, ball-lock actuating cylinder.
8-3
