Coin Machine Review (& Pacific ...)

Short Cuts in Electric Motor
Maintenance
J
by Ernest W. Fair
No matter how much care and precaution
may be taken in the operation of motors in
coin machines and in the operator's shop
all will be wasted unless they receive the
proper care during the long tenure of their
operation. Strict maintenance standards are
necessary.
In mounting or remounting motors they
should be so set that they are protected
from moisture, steam, dripping pipes, oil,
acid, alkali and any form of gas. It should
be protected from dust, be well ventilated
and accessible for cleaning and inspection.
Any foreign materials entering motor arma-
tures will ruin them. While the motor is
running it is advisable to blow some smoke
toward it and note how the smoke is forced
through the motor by its ventilator. Foreign
materials can be as easily drawn into the
motor if they fall into the path of this
draft.
Motors intended for floor, wall and ceil-
ing mounting generally have end shields
or bearing housings which can be turned
through 90 to 180 degrees. The end shields
or bearing housings should be turned
around the corresponding angle and the
connections properly rearranged. Care
should be exercised to see that the surface
of joints are clean, otherwise alignment
may be so affected as to heat the bearings.
The air gap should be checked to see that
it is uniform all around after the end
shields have been bolted into place.
Motors should be lined on their founda-
tions so that driving and driven shafts are
paralleL Pulleys must be in line so that
the belt will run true. Driving pistons and
gears must mesh accurately. Full assurance
that pulleys are properly aligned can be
obtained by temporarily installing the belt
and running the pulley by hand.
Geared machines must be accurately
aligned and rigidly fastened to a common
base as an error of a few thousandths of an
inch will produce serious vibrations that
will ultimately break the shaft or wreck the
machine. When gears are properly meshing
it should be possible to pull a thin piece
of paper from beneath the teeth without its
tearing.
The life and successful operation of elec-
tric motors depends on two things, their
proper installation and upon maintenance.
Electric motors generally require less care
than any other type of power apparatus,
but neglect of fundamental requirements
of their maintenance will foment serious
troubles that will result in loss of equip-
ment and hamperance of operation.
The particular stresses and strains in
coin machine practice makes a systematic
inspection at least once a week advisable.
Cleanliness is of great importance. Free-
dom from water, oil, dirt, grease or foreign
materials, inside and out, is insurance of
efficient operation. It is always advisable
to have a periodic removal of the motor or
armature.
Some mechanics use compressed air in
cleaning, which is not advisable, as the air
will drive foreign materials into the wind-
ings of the armature and cause break-
downs.
During inspection bearings should not be
removed from shafts unless absolutely nec-
essary. Removal tends to impair their fit.
The safest procedure in cleaning is to
treat the motor as you would any high-grade
piece of machinery. The proper amount of
oil shou1d always be in the oil wells. Excess
oil will run down onto coils and soak their
insulation, dirt and dust will then fill up
tI)e spaces between the oil-soaked coils and
air circulation will be shut off. Overheat-
ing and destruction of the armature will
result.
Bearing life is affected by lubrication,
belt tension and shaft alignments. Ade-
quate lubrication, proper belt tension and
accurate alignment will reduce excessive
wear and tear on motor bearings.
Hot bearing troubles can generally be
traced to oil that is too heavy, or too thin,
dirt and grit in the oil, too tight belts,
gears meshing too tig'htly, pulley hubs rub-
bing against bearings, the motor not being
properly aligned causing the armature
shaft shoulder to pull against one bearing,
or the shaft may be sprung.
If the armature is striking the iron of
the field it is a sure indication that bear-
ings are worn and should be replaced. A
heavy rumbling sound at the time oJ start-
ing usually indicates a bearing that is badly
worn although the armature does not quite
touch the field.
Attention should be given to lubrication.
Oil wells should be filled with petroleum
oil, sometimes specified as high-grade dy-
namo oil. Animal or vegetable oils or
admixtures of them with petroleum oil will
dry and gum and thus prevent the free
flow of oil to the bearings. Oiling should
be done through the oil filler or overflow
gauge while the motor is at a standstilL
Wells should be filled to within one-six-
teenth inch of the top of the overflow
gauge.
Motors are usually shipped with sufficient
grease in the bearings to last for a limited
period. The bearing-housings should be
almost one-half full of good quality neutral
bearing grease added when necessary to
bring the level to this point. Old grease
should be entirely removed and replaced
with fresh grease once yearly.
Brushes should almost move freely in
their holders and at the same time make
firm, even contact with the commutator. If
they stick in the holders it is usually due
to an accumulation of dirt and oil. Brushes
should all be of the same length.
When replacing, brushes should be fitted
by means of fine sandpaper folded around
the commutator with the rotor being re-
volved by hand in the desired direction
until the proper fit is obtained.
The position of brushes should not be
shifted unless it is known that their posi-
tions are incorrect or to change the direc-
tion of rotation or mounting. On motors
with commutating poles the position of the
brushes is fixed on the neutral point at the
factbry. This position should not be shifted
except to make changes or for compound-
ing or parallel operation.
Pigtails or flexible copper conductors
should be firmly fastened in place in order
to carry the full current from the brush
to the holder. A slight extra length should
be left because if they are too tight the
brush will be pulled out of line and out of
proper contact with the surface of the
commutator.
Commutators should be clean and well
polished. A piece of canvas or non-linting
material is best. No vaseline or oil should
be used on a commutator. Roughness is re-
movable through polishing with a piece of
sandstone having the same radius as the
commutator. Sandpaper pressed against the
surface of the commutator with a block of
wood like the sands't(}~e may also be used.
The commutator shOlild be run at a high
rate of speed during polishing and the sand-
stone or sandpaper m.9ved back and forth
along the surface parallel to the shaft. Then
they should be carefully cleaned of any
grit which may scratch the surface of the
commutator. Emery cloth should . never be
used on a commutator or brush.
Excessive heating of motors can gen-
erally be traced to three principal sources;
in the armature-heavy overloads, exces-
sive room temperatures, short circuits or
grounds, dirt obstructing air passages and
excessively worn bearings; in field coils-
short circuits, grounds or excessive voltage
and in the commutator-sparking or exces-
sive brush tension.
When a motor fails to start upon applica-
tion of power the cause can generally be
traced to four faults: (l) Cut out contact
dirty, phase circuit not closed, (2) Open
phase winding, (3) Open main winding,
and (4) Tight bearings.
Correct maintenance insures not only
successful operation but full value from
investments in electric motors.
•
Industry Triumphs
In Slug Botlle
SAN FRANCISCO-The Coin Machine
Industry has just finished a real life story
in crime detection that ought to make the
Crime Club thriller lists for June! A man-
ufacturing com pany official as investigator!
A prominent distributor playing detective!
And a last chapter ending in a courtroom
with Police Judge Chris B. Fox giving
"Sluggers" Stanley Sains and Jack Greiner,
of Oakland, a $300.00 fine and two years'
probation.
The beginning of the tale was presented
by Mr. Williamson of the Glenn-Rowe
Company, who reported a sale made by a
sheet metal firm. This particular sale in-
volved a bit of counterfeiting by Sains and
Greiner who made the metal into slugs for
coin machines.
Acquiring excitement as it went along,
the real life crime investigation got drama
with Richard A. Parina, Western Distri-
butor for Arthur H. DuGrenier, Inc.,
posing as a private detective outside the
metal company's door, nabbing the slug-
makers as they were leaving. Since Parina
still resembles the hardy player he was in
the days when he achieved football fame,
he had little difficulty in holding the cul-
prits for Inspector Robinson of the Oak-
land Police Department.
District Attorney George C. Perkins .
supplied the climax for, after making an
intensive study of the entire slug situation
and presenting a brilliant case against the
slug practice, he won a conviction for both
prisoners.
Sains and Greiner pleaded guilty to
punching the metal into nickel and dime
size plugs at a specially equipped machine
shop and using the slugs to steal cigarettes
from machines.
Their racketeering business ended with
their arrest.
•
*
*
*
"What's the best thing to do for
insomnia? I have a bad attack of it."
"Just go to bed and sleep it off."
C O IN
MACH INE
REVIEW
11
FOR
JULY
J94J