Telescope and cable operation
RESTRICTED
rate of drive and independently of the rate of
drive.
If the displacement knob
is rotated clock-
wise
the
rate
of drive is increased
and
the lower
traction gear
moves in
the same direction as the
upper traction gear.
If a very rapid dispiacement of the optics is
required, disengage the displacement clutch and
engage the
search knob bevel
pinion with the
search knob bevel gear.
Rotate the search knob.
The bevel search knob
gear is rotated. and will
rotate the tee head shaft and telescope
rack drive
pinion causing the rack to be displaced.
The telescope is driven through a system of
gears,
five
sheaves and a cable.
The cable oper-
ating sheave, or number one sheave gear, is in
mesh with the
telescope quadrant sector gear.
the quadrant rotates the cable operating sheave is
rotated in
the opposite direction.
(The sheave is
free to turn on the
gear shaft but is held stat-
ionary by a clamp and eccentric screw.)
The clamp
fastens
about the gear shaft and the eccentric
screw fits into a slot on the
sheave.
A one-half
turn of the eccentric screw in
either direction
give adjustment on the
cable without rein-
stalling.
This
is approximately l degree.
The number two sheave is located to the right
of the cardan gudgeon
bearing in the rate end.
The number three sheave is mounted to the cardan
on the left side of the cardan bearing.
The num-
ber four sheave is mounted in the cardan, and the
telescope cradle gudgeon pin is milled and drilled
to permit passage of the cable over the sheave and
through
the gudgeon
bearing
to the number five
sheave which
is mounted
the telescope cradle.
The number five sheave is pinned to a gear shaft.
gear is: in mesh with
the telescope sector
The number one sheave is the cable operating
sheave.
An extra
flexible nine-strand
bronze
cable transmits the drive to the
telescope.
The telescope return spring supplies a ten-
sion to the telescope about its transverse
ax is
and maintains a tension on
the cable
and will
re -
turn the telescope toward maximum.
1f it
were not
for this tension there would be no way of
return
ing the
telescope to maximum.
74