Disc and search-knob assemblies
RESTRICTED
Fig. 34
F. Disc
Assem-
bly
Fig. 34
G. Search
Knob
Assem-
bly
H. Trail
Assem-
bly
N,O.P.
#649
Fig.
30
and
34
:. Rate
İSSEN-
34
The rate
knob enables the bombardier to set
up the correct
rate of drive so
that he can syn-
chronize by positioning the roller on the disc.
The disc
assembly consists of the disc,
tach-
ometer shaft, tachometer shaft springs, bearing
blocks,
bearings and
screws, inspection plate and
tachometer connection.
The disc drives the
roller which
translates
the drive to the rate and telescope drive mechan-
• The
tachometer shaft
spring
supplies
the
tension which holds
the disc against the roller;
the tachometer shaft and connection
transmit the
speed
disc to
the tachometer when the
tachometer is applied.
The search knob, shaft and bevel pinion are
parts of
the search knob assembly.
It is used to
displace the optics quickly
independently of
the displacement
The search knob must not
be used without
disengaging the displacement
clutch because of the danger of shearing the dis-
placement clutch pin.
This consists of the following: trail plate
(see rear view of sight), trail arm, trail setting
gear, nut gear, thrust washer and
spindle screw.
trail
arm is rotated toward maximum trail
the trail setting gear rotates the nut
gear which
moves up on
the threaded
upper spindle
bearing
against the thrust washer which carries
spindle
in translation against
the tension
the spindle
spring.
The roller is thus moved
up from
the disc center a distance proportional
to trail without affecting the rate
mechanism.
The spindle spring forces the spindle screw
in translation downward as the trail arm
toward minimum.
The
race assembly consists of the rate knob
intermed: =*=
beve! pinton,
"EtE SEVE:
-=:€
real ning
So ring:
scircle
er and roller carriaçe,
2EE"
rate rack pinion.
Pate
ou&crant
camkay, rate index, automatic release
points,
ground
speed drum and
ground speed scale.
This synchronous assembly sets up the rate
of drive necessary to synchronize on the target.
71