Advertisement
l42l
must be clean and
rotate freely on the shafts. The tension guide
assembly (41) must pivot freely without binding-
A rhythmic movement of the tension guide
roller assembly indicates that a roiler or the
sound drum is binding or out of round. An out-
of-round or bent #2 sprocket drive will also
cause exc€ssive tension guidc movement. All
cf the above symptoms will result in abnormal
wow and flutter. The tension of the guide and
roller assembly is determined by spring {49} and
can be adjusted by replacing the spring or slightly
stretching ar shortenlng the rpring to achieve
rninimum wow and flutter. All nylon rollers
shauld be cleaned wirh alcohol and lubricated
sparingly with silisone oil.
7. #2 Sprocket And Shoe Assemblyi
Fis. #97
-- 43
The drive consists of the sprocket cover (48),
the sprocket teeth plate (47), the sprocket drum
and shaft {45}, the hub and bushing assembly
(50), and the drive gear (52). There must be no
end play of the sprocket drum shaft in the
bushing. Small fibcr
washers {G4-070120,
G8-0701?0| are insta|led to achieve this condi-
tion. The sprocket plate (47) must be in good
condition, with no defective sprocket teeth,
otherwise it must be replaccd. For correct
timing adjustment of the #2 sprocket drivc
assembly, refer to the loop setter section.
{ S e c . 5 4 }
The #2 sprocket shoe keeps the filnr in sontact
with the sprocket teeth. The shoe should always
remain closed on all self-threading projectors-
The shoe tension is maintained by the "V"
spring (55). lt is important to note that the #?
sprocket shoe spring is stronger than the $1
sprocket shoe spring, The proper clearance
between the shoe {53} and the sprocket drum
{a6} is very important. To test this clearance,
take short piece of film and feed it into the #2
sprocket using the inching knob to advance tJre
projectors mechanism. Add anotherstrip of film
ofl top of the first and advance the projector.
With a double thiskness sf film the film shoe
should not begin [o open. Add a third layer cf
film and advance the projector. This time the
film shoe should begin to open, indicating that
thc shoe clearance is correct.
NOTE; A simple test film may be made by
cementing three short strips of film
together. (See Sec. 5-5-B-1, Nate)
F -
l S c m - *
The proper film shoe cleara.nce is dctcrmined by
a small protrusion moldcd on the shoe which
indexes the shoe against the bushing hub {50}.
Fis. SB
Y
L 5 5
FILMSHOE
PROTRTJSIOH
As the shoe wears it may be necessary to replace
it to ohtain the correct clearance- In some eases
the shoe clearancc may bc rcduced tly filing thq
protrusion-
!!UTION:
Too close a clearance will reufl i61
poor threading or possible nlql
damage.
52
47
,18
{
59
58
54
53
T'
Fig- *"9g
*
3cm .f
.----8cm-d
- 5 8 -
Advertisement
