MOTORS FOR MECHANICAL DISPLAYS.
The best motor for all general purposes is without doubt an electric
motor. These can be procured at a moderate cost as small as ¼-horse
power, which is sufficient for an ordinary mechanical effect.
THE ELECTRIC MOTOR
May be attached to the regular supply wire, and is so little trouble to
the trimmer that it is preferable to all other motors whenever it can be
used. It is frequently necessary
TO REDUCE SPEED
Of an electric or fan motor, and the simplest method is to attach
incandescent lights to it. For a fan motor two 32-candle power
incandescents will materially reduce the speed, as they cut off just the
amount of power required to run them.
In towns where there is no electricity one of the following simple
motors will be found serviceable and easily constructed:
A WATER MOTOR.
The water motor is made of tin, in the same form as an ordinary overshot
water wheel, is 30 inches in diameter by 3 inches wide, with a ½-inch
rod through the center. A 2-inch pulley is fastened to one end of the
rod, for the belt. Any tinner will make one of these motors and incase
it in tin for $5 or $6.
ANOTHER TYPE OF SMALL WATER MOTORS.
There is usually plenty of water available in stores, and it does not
require much pressure to get from two to five horse power from a little
motor of so simple design that almost any one can construct one with a
few tools and at small cost. The accompanying description is for making
a motor from which to obtain air for a sand blast, wind power for window
devices, etc. The wheel consists of a cylinder on a shaft, having nearly
semi-circular buckets on its periphery. The water is directed by the
nozzle nearly tangential to the upper side of the bucket, and after
traversing around the wall of the bucket it leaves in a nearly
horizontal line in the opposite direction to that from which it entered.
As the water leaves the bucket it drops slightly below the level of the
wheel and falls into the basin, from which it passes off through a drain
pipe. The water power is direct from a hose. The motor will be very
useful for operating mechanical window devices. The wheel is sixteen
inches diameter, and the buckets are one and one-eighth inches square
and two inches apart, and they are made of galvanized iron, soldered
together, while the wheel is one off from an old ordinary bicycle.
[Illustration:
A SIMPLE WATER MOTOR FOR RUNNING WINDOW DEVICES.
]
The axle is a piece of old water pipe. An empty box will do for the case
for the wheel. A wheel of these proportions, run with about sixty-five
pounds pressure per square inch at the nozzle the latter having ⅞-inch
jet, should revolve the wheel at a speed sufficient to develop two-horse
power. The water pressure is taken in at the nozzle, and the outlet is
at the bottom. If possible, take the water from the main pipe coming
from the street main and reduced to one and a half inches, just before
reaching the motor. With a head of water of forty feet, a power
amounting to about 1½ horse power is obtained, using one nozzle. This is
sufficient to run an 8 or 10-inch fan, a small dynamo or other light
machinery in the store.
THE SAND MOTOR.
For slowly moving mechanical displays the following motor is reliable
and satisfactory:
A frame of wood (a) is first made, in which is placed a shaft (c) and a
wooden pulley (b). The pulley should be tightly secured to the shaft,
the end of the latter resting in a step (d) secured to the bottom of the
frame. Upon the top of the shaft place a circular board, which holds
your display. A cord is run once around your pulley, and then over a
small wheel (e) at either side, from whence both ends drop through a
hole in the window floor. One end of the cord is weighted, the other
connected with a flat weight resting upon the sand, which is your motive
power. Make an upright box, as shown in the illustration, with a
partition in the middle. In the center of the partition make a small
hole for the sand to filter through. The size of the hole regulates the
speed of your motor. The box should have a cover for each end. As the
sand falls through the hole in the partition the weight which rests upon
the sand falls also, your pulley wheel being revolved at the same time.
When the sand has run through, which may be in an hour or six hours, as
you will arrange, cover the top of the box, reverse it, and place the
weight upon the sand again. It is the same principle as the hour glass,
and is easily made and operated.
[Illustration]
THE CLOCK MOTOR.
This is not very strong, but is capable of running simple and evenly
balanced mechanical displays.
Procure a common wooden weight clock, such as is called a “Columbus
Clock.” Any jeweler can purchase it for you at a small price, if he has
not one in stock. Run a wire through the highest geared wheel, sharp on
one end, to run on a pivot acting below. Connect your fixture to this
pivot wheel. Pull up the weight, and the mechanism will run very easily.
It needs to be rewound every three hours. To increase speed, add to the
weight. If your mechanism is nicely adjusted, it will require no more
power to run it than may be obtained from one of these clock motors.
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