Le Pontois' Electro-Magnetic Speed Changing Gear.
The speed changing gear with magnetic clutches, invented by Dr. Leon Le Pontois
and which was exhibited on a car at last year's Madison Square Garden Show, is
stated to have now been reduced to a thoroughly practical state, and will probably
soon be available in the market. The gear, of which a cross sectional view is shown
herewith, combines the planetary and lathe back gear principles, and all speed variations
are secured by magnetic friction clutches running in oil. The gear gives
three forward speeds and one reverse (direct drive on the high gear), and is very
compactly housed in an extension of the engine crank case. The engine flywheel
forms part of the gear, and it is stated that the gear for a double cylinder vertical 20
horse power engine weighs 300 pounds.
The flywheel A is mounted on the end of the shaft O, and constitutes a triple
magnetic field. It has annular grooves B, C and D cut in its surfaces, in which
are located coils enclosed in copper shells, hermetically sealed, protecting the winding
and its insulation from the action of the oil, and constituting at the same time a
damping circuit, shielding the coils from the field discharge. When these coils are
energized by an electric current a magnetic field is formed in the mass of the flywheel
which attracts and holds firmly the armature disks I, J or K. The current is sent
through these coils by means of wires leading to contact rings W, and by brushes X
to the source of electrical energy.
Annular fields E and G are held fast in the casing. A shaft M with bearings in the
shaft O and in the driven shaft N supports the armature disks and the gears. A disk
L keyed on the shaft M supports a shaft V carrying the pinions Q, S and U. A
gear P meshing with pinion Q is locked on the driven shaft N. A sleeve carries
the gear R and the armature disk J, gearR being in mesh with gear S. A second
sleeve carries the armature disk K and gear T, which meshes with gear V. The shaft
M also supports the armature disk I keyed on it.
When it is desired to run at a slow forward speed the disk L carrying the shaft V
is made stationary by being attracted and held fast by magnetic field G energized by
coil H. The pinion R is made to rotate with the shaft O by the armature J held
against the flywheel by coil C. The pinion R then drives the shaft V and shaft N
through the intermediary of gears S, Q and P at a low rate of speed.
To obtain the second speed, while disk L is held stationary, armature J is released
and current is sent through coils D. Disk K then turns solid with the flywheel, and
gear T drives shaft N through the intermediary of the gears V, Q and P.
Now let it be desired to engage the high speed. Clutch D is still magnetized. Disk
L is released from the grip of clutch G and disk I is attracted by clutch B. The whole
system of gears now rotates solid with the shaft, the whole mass forming a heavy flywheel.
To reverse, disk K is made fast to clutch E by coil F being energized; at the same
time disk I is made fast on the flywheel by coil B being energized. The disk L carrying
the secondary shaft V rotates with shaft O. The epicycloidal path described by gear
S being different from the path described by gear Q, the gear P rotates slowly in the
opposite direction to shaft M and thus the reverse motion is obtained.
Only six gears enter into play in these successive operations.
An oil pump driven by shaft N forces oil under pressure through the bearings of the
shaft M and bushings rotating on that shaft. This oil forms a thin film between the clutch
surfaces and the armature disks, which plays a very important part in the progressive
clutching and releasing of the disks when the field magnets are energized.
A simple generator, designed to deliver a constant current at whatever speed the engine
is driven, is used for operating the clutches up to 15 horse power. This generator
is of the ironclad type. A foot pedal, placed in series with the electric switch controlling
the fields, acts directly on an inductive rheostat, or choke coil, to enable the
operator to start the car with ease. The clutches are interlocking; that is, it is impossible
to engage two at the same time.
Tests are said to have shown that the energy required to magnetize the fields
amounts to somewhat less than half of 1 per cent, of the power transmitted. A
working model of the gear is shown at the office of the company owning the patents on
it, 200 Broadway, New York.
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