the Accutron guarantee of
ACCUTRON timepiece is guaranteed by Bulova not
to gain or lose more than one minute a month in
normal use as a wrist timepiece. For one
full year from the date of purchase and without
charge, it will be adjusted to this tolerance,
if necessary, as stated in the following
timepiece is guaranteed
internationally by Bulova not to
gain or lose more than one
minute a month in normal use as a
wrist timepiece, and is guaranteed
against all damage and defects,
except loss, fire and theft.
For one full year from date of
purchase from an authorized ACCUTRON
Jeweler, it will be repaired,
serviced or adjusted, if necessary,
without charge, if returned to the
authorized ACCUTRON jeweler from
whom it was purchased, or to any
Bulova factory, office or
NOTE: Authorized ACCUTRON jewelers
have been instructed to complete, within
thirty days of your purchase, a registration
card that details specific information
concerning your ACCUTRON timepiece and to
send it to Bulova Watch Company, Inc.,
Bulova Park, Flushing, New York 11370.
characteristics of ACCUTRON
timekeeping -- ACCUTRON vs. conventional
performance of any wrist timepiece is judged by the way
it keeps time in actual use. Performance depends
upon the extent of the timepiece's immunity to the many
disturbing environmental factors encountered in use.
The ability to cope with these detracting influences
varies considerably from watch to watch. In
conventional timepieces it depends upon:
1. The excellence of its initial
construction and factory "adjustment".
2. The skill with which the most
recent repair was made.
3. The amplitude of oscillation of the
balance wheel, which depends principally
upon the state of the lubrication.
ACCUTRON movement, on the other hand, the
timekeeping capability is governed principally by
the "designed in" characteristics of its tuning
fork. Also, since the tuning fork has no pivots
or bearings, its timekeeping is free from the
effects of lubrication.
quantitative comparison of the performance
capabilities of ACCUTRON timepieces and conventional
watches can be made only by laboratory tests, in
which identical conditions of operation can be
maintained. For such comparisons the Watch
Timing Tests of the Official Swiss Testing Bureaus
are very useful. Among these tests is one for
wrist "chronometers". These watches are
regarded as the most accurate conventional watches
available. Watches fulfilling the requirements
of this 15-day test are awarded individual
certificates by the official testing agency.
Should a watch meet somewhat closer performance
criteria, the award is issued with "mention" for
particularly good results. The performance criteria
which must be met to qualify for such distinguished
awards are shown in Table I. Also shown are
the corresponding characteristics of the ACCUTRON
movement, as established by design or manufacturing
Table I the relative capabilities of the ACCUTRON
timepiece and the best conventional watches,
under laboratory conditions, are clearly evident.
In normal service, the superiority of ACCUTRON
performance is still more striking.
conventional watch which gains or loses as little as
a minute a month in actual use is very exceptional;
in other words a "freak". To provide such
performance in quantity production would be
fundamentally impossible. For ACCUTRON,
however, that same minute a month is a maximum
error. Achievement of such accuracy is the
direct result of the basic superiority of the tuning
fork over the balance wheel and hairspring. It
is this difference which has made possible Bulova's
guarantee that ACCUTRON will not gain or lose more
than a minute a month in normal use as a wrist
timepiece. This guarantee is a new criterion
for judging watch performance.
Comparison of Timing Tolerances for
with Inherent Performance
Characteristics of ACCUTRON
seconds per day)
Regulation - Mean rate in 5 positions at
-3 to +12
-1 to +10
-2 to +2
Mean variation in rate for above test.
less than 1
Largest variation in rate for above
less than 1
Rate difference between 6 up and dial
Largest difference in rate for any of
the 5 positions tested and mean daily
Rate-Temperature Coefficient in sec/day
°C from 4° C to 36° C.
Recovery (change in rate as result of
exposure to temperature test).
less than 1
effect of position on ACCUTRON
the major factors contributing to the timekeeping
accuracy of the ACCUTRON movement is its small and
predictable position error. The tuning fork has a
basic position error which is completely predictable in
amount of direction. Furthermore, this position
error is independent of tuning fork amplitude.
long dimension of the tuning fork is horizontal, the
frequency of vibration is the same, whether the tines of
the fork are alongside each other or one above the
other. In most ACCUTRON models, the tuning fork is
mounted along the 12-6 axis of the movement.
Therefore, the rates in dial-up, dial-down, 3-down, and
9-down positions will all be precisely the same.
long dimension of the tuning fork is vertical with the
times down, which is the 12-down position in most
ACCUTRON models, the effect of gravity causes a slightly
higher tuning fork frequency. In this position the
rate is 5 seconds per day faster than when the fork is
in a horizontal position. Conversely, when the
fork is vertical with the tines up, the frequency of the
tuning fork will decrease, causing a rate 5 seconds per
day slower than when it is in a horizontal position.
This is the 6-down position in most Accutron models, and
is rarely experienced when the watch is worn on the
outside of the wrist.
extremely small position error is taken into
consideration in the regulation of ACCUTRON movements at
the factory. It is regulated for best timekeeping
when worn on the outside of the wrist. It is
recommended that when the owner desires to wear his
ACCUTRON timepiece on the inside of the wrist (making the
6-down position occur more frequently), it should be
regulated 3 seconds per day faster than the original
the effect of temperature on ACCUTRON
elements in the ACCUTRON electronic circuit are chosen
to provide for reliable performance under temperature
extremes from 20 degrees F to 120 degrees F.
Outside this range, performance or timekeeping ability
may be unsatisfactory. It should be remembered
that this will have no effect on operation under normal
conditions, since the ACCUTRON timepiece is meant to be
worn on the wrist, and when it is, will be within a few
degrees of body temperature, even in extreme cold or hot
of temperature on its rate is considerably less than for
normal high-grade wrist watches. If removed from
the wrist at night, the temperature of the timepiece may
change considerably. However, the net effect upon
the daily rate is small since the temperature error is
small by design, and the exposure to the "abnormal"
temperature does not usually exceed 8 hours daily.
the effect of shock on ACCUTRON
ACCUTRON timepiece, on the wrist of the user, is
completely immune to the shocks of gardening, playing
golf or baseball, hammering, etc. Repeated blows,
directly on the side of the case, can temporarily affect
the operation of the mechanism and cause a change in
time. However, it is so protected, when worn in a
normal manner on the outside of the wrist, that repeated
accidental bumping, sufficient to affect the timepiece,
means have been included in the design of the ACCUTRON
movement to minimize the possibility of damage if the
timepiece is dropped. The most sensitive parts of
an ordinary watch are the pivots on the balance wheel
staff. Conventional watches are shock-protected by
special spring mountings for the jewels for these
pivots. In the ACCUTRON movement, shock protection
has been provided by using a shock bridge and stops to
limit the maximum movement of the tuning fork tines, and
by a guard surrounding the index and pawl jewel fingers.
great enough to break a balance wheel pivot in a
conventional "shockproof" watch may, in ACCUTRON,
derange the indexing mechanism. Restoring the
mechanism to perfect operating condition requires only
minor adjustments by the repairman, in comparison with
the major operation of replacing a balance staff.
possible has been done to protect the ACCUTRON mechanism
from the shocks of normal use. However, like any
fine precision instrument, it should be treated with the
respect it deserves.
the effect of vibration on ACCUTRON
ACCUTRON movement, if mounted directly on a vibrating
structure or maintained in contact with it, may be
affected by vibration. The effect, if any, would
depend upon both the frequency and direction of the
vibrations. However, the wrist of the user
cushions the ACCUTRON timepiece, so that direct exposure
to vibrations which can affect the tuning fork is
impossible. The use of power hedge trimmers, power
mowers, sanders and other such vibrating equipment will
have no effect on an ACCUTRON timepiece worn on the
the effect of magnetism on ACCUTRON
timepieces are less affected by the magnet fields
usually encountered in normal service than are
conventional "anti-magnetic" watches. The
criterion for an "anti-magnetic" watch is that, when
subjected to the influence of a magnetic field with a
strength of 60 gauss and then removed from this
influence, it shall operate without being affected more
than 15 seconds per day. The ACCUTRON timepiece
easily meets this specification, changing rate on a few
seconds per day.
ACCUTRON timepiece should not be deliberately exposed to
an extremely high strength magnetic field, as in a
demagnetizer or a strong permanent magnet, since it is
obvious that it would be possible at some level of field
strength to demagnetize the permanent magnets on the
tuning fork. If an ACCUTRON timepiece is
accidentally demagnetized it will stop, and the tuning
fork must be replaced or returned to Bulova to be
the effect of altitude on ACCUTRON
like conventional watches, is affected by the changes in
barometric pressure associated with changes in altitude.
In conventional watches, other effects are so large that
rate changes of several seconds per day are rarely
noticed. In ACCUTRON, although the rate change
with altitude is about the same as for conventional
watches, the effects of pressure changes on its
performance are more likely to be apparent because of
its very small rate of gain or loss.
ACCUTRON tuning fork will gain at increasing altitudes.
Up to about 15,000 feet the effect is to gain 3 seconds
per day for each 5000-foot increase in altitude.
This effect is caused by the change in density of the
moving air column which, in principle, forms part of the
mass of the vibrating tuning fork.
effect does not normally result in any significant
problem. The ACCUTRON owner who is permanently
located in an area substantially above sea level may
find it necessary to return his timepiece to the local
jeweler for regulation, to correct for a gaining rate.
Temporary exposure, such as in air travel, has a very
slight effect. For example, a 6-hour flight at a
"cabin altitude" of 5000 feet (which is conventional)
would cause an ACCUTRON timepiece to gain 3/4 of a
second more than if the owner had remained on the ground
at sea level.
jewels in ACCUTRON
of jewels in a watch movement has traditionally been, to
the consumer, an indication of quality. However,
since the ACCUTRON movement uses an entirely new system
of timekeeping, there is actually no basis of comparison
with conventional watches. As a matter of
information, the ACCUTRON movement has 17 points of
possible wear, all protected by jewels.
ACCUTRON models are of standard "waterproof"
construction. The primary purpose of this case
construction is to prevent trouble due to accidental
immersion and to perspiration, dust, etc. entering the
case. Each "waterproof" ACCUTRON timepiece is
individually tested before it leaves the factory to
assure that it does not leak. Some users wear
these timepieces while bathing and swimming.
However, deliberate subjection of a fine timepiece to
the hazards of such exposure is not encouraged by
Bulova. The case construction required to provide
protection for activities such as skin diving is
somewhat undesirable for normal use because of styling
considerations and has therefore not been employed in
any ACCUTRON models.