Boxoffice-October.01.1955

PROJECTOR MAINTENANCE
Continued from page 26
off with a slightly moistened cloth, either
water or solvent. Do not scrape shoes or
pad with any steel object as you may
damage the highly polished surface—use
a soft coin if you need to scrape emulsion
off.
The tension of the pad is adjustable over
a wide range through tension springs (Pig.
1, No. 3 and 4 ) . Just enough tension should
be applied to the film in order to hold it
firmly, any more than this will cause unnece.ssary
wear of sprocket teeth. Only
sufficient tension to keep the picture steady
on the screen is all that is required at any
time. It is suggested, by the manufacturer,
until you are thoroughly familiar with the
pad tension, that the adjustment nuts be in
about mid position. The company has provided
a safety feature on the adjustment
by providing stops, so that the tension adjustment
nuts cannot be tightened so far
as to lock the film in the gate. It has
always been found desirable to operate with
as little tension as possible on the pad and
still maintain a steady picture on the
screen. Save unnecessary wear on the
sprocket, shoes and pad by using a lighter
tension on the pad.
The upper and lower pad roller arms are
opened by pushing the roller knobs toward
the rear of the mechanism. The pressure
pads on the intermittent sprocket are
opened by pushing the knob downward.
The arms should always be kept correctly
adjusted as they play an important part
in the mechanism.
The upper and lower pad rollers in open
position provide for automatically setting
the loops above and below the gate. A very
special feature of the Century projector.
Also, the lower pad roller provides a means
of measuring the correct distance on the
film between the picture aperture and the
sound aperture.
SPECIAL TENSION DEVICE
You will note, on the illustration of the
film side of the mechanism, there are no
tension springs showing on the pad rollers,
each has a scientifically designed tension
device built right into the pad roller arm
providing just the proper amount of tension
for optimum performance. Each pad
roller has a positive stop. Be sure to clean
the rollers every day and see they turn
freely and do not develop flat spots. The
correct distance of pad rollers is the distance
of two thicknesses of film between
the pad roller and sprocket.
NOTE—In the field the writer has always
found it sound mechanical practice to
periodically (every two or three months)
check over the entire projector and sound
head. Mounting screws, holding screws, and
like parts should be checked for tightness.
This is particularly applicable to parts installed
in the field, such as drive parts,
including the main drive gear screws, sound
head adapter parts, pad roller brackets for
alignment, etc.
EASY TO SERVICE
It's no mystery that adequate screen lighting demands an adequate
power supply. This is especially necessary with today's wide screens,
requiring more light over a large area.
The Hertner HT 135/270 Transverter meets these needs and gives
users an ample source of constant D.C. power. The generator has a
capacity of 90 volts and is designed for continuous operation at 135
amperes with a capacity for 270 amperes during changeover period.
Complete installation includes Control Panel Type G and the Dualtype
HD 100/140 Rheostat.
For all the details of the many fine features of the HT 135 Transverter
write for Bulletin No. 30 IB.
Distributed by Notional Theatre Supply
In Conodo: General Thcotrc Supply Compony
In Los Angeles: Pembrcx Theatre Supply Corp.
THE HERTNER ELECTRIC COMPANY
12690 ELMWOOD AVE. • CLEVELAND 11, OHIO
MOTORS • MOTOR
1
GENERATORS • GENERATOR SETS
A SUBSIDIARY OF GENERAL PRECISION EQUIPMENT CORPORATION
28
The Century mechanism is very easy to
service as the mechanism consists of unit
assemblies such as: the intermittent movement
with intermittent sprocket pad; the
main drive shaft, the vertical shaft, the
shutter shaft, the film trap, the film gate,
the upper and lower sprockets and shafts,
the upper and lower pad roller arms, the
lens holder and gate control knob. All of
these assemblies can be removed and replaced
with new by almost any intelligent
projectionist, the illustrations elsewhere In
this article showing you the location of each
part. When the projector reaches the stage
where it needs a complete overhaul, it
should be sent to an authorized Century
dealer who will supply a loan mechanism
while the rebuilding job is being done by
an expert mechanic in a shop equipped with
precision tools and machinery. Spare parts
should be kept in the parts cabinet in case
of emergency.
The writer has compiled a two-page
service bulletin on how to replace inter^
mittent sprocket, cam and starwheel, cover
ing adjustments in order to secure perfect
results. As this is the "heart" of your
projector, the writer has given special
treatment to the servicing of this move
ment. We wanted to conserve space tc
cover other important components. Tht kl
bulletins are free to all subscribers anc
will be mailed promptly if a self-addressed
The MODERN THEATRE SECTIOI
lOJi