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The voltage regulator operates on the vibrator principle, and is designed so that when the voltage becomes higher than the predetermined amount the vibrator throws a resistance into circuit that reduces the amount of current flowing through the field, as has been previously described. Nothing in the wiring is unusual and the diagram may be easily followed in view of the complete explanation previously given of the Bijur systems.
Fig. 226.—Simplified Wiring Diagram Showing Action of Simms-Huff
Starting and Lighting System.
The Simms-Huff Single Unit System.-The operation of this one unit system differs from the Dyneto in that the wiring arrangement is so designed that the non-stalling feature is eliminated. The simplified wiring diagram which is presented at Fig. 226 shows that this system operates on the one wire method, and that the wiring is such that a 12-volt series battery arrangement is used in starting while the 6-volt parallel charging scheme is followed. The starting switch, which may be either foot- or handoperated, automatically controls the battery connection and provides a wiring scheme for the lighting circuit which insures healthy battery action and makes for minimum fluctuation in candle power when the motor, for instance, is being cranked with the lights burning or at the other extreme when the engine is raced. Through the inherent winding arrangement, when the motorgenerator is used for starting, it automatically becomes a 12 volt cumulative compound motor which on being driven by the starting of the engine becomes a differential dynamo and charges the batteries at a predetermined rate which can be varied by a single regulator adjustment that is easily made.
The small diagrams in Fig. 226 show the inherent winding arrangement which automatically accomplishes these results. On
Fig. 227.-Curve Showing Current Output of Simms-Huff Generator.
examining the directions of the arrows it will be seen that the eurrent which the arrows represent flows in the opposite direction in the series field when charging than it does when starting. The action of the powerful field winding is to assist the motor when starting by increasing the strength of the magnetic field and to weaken the field strength of the dynamo when charging and prevent an overcharge at high speed. In this manner it automatically assists the regulation of the charging current delivered to the battery. The charging current increases from zero to its maximum with a very small increase in car speed. This is clearly shown in the graphical diagram at Fig. 227, as this outlines the rate of charge in amperes corresponding to car speed in m. p. h. with the ordinary gear ratios and wheel sizes. This curve illustrates a sudden rise in current which starts at a speed of about 12 m. p. h. and which reaches its full value of 10 amperes before the speed is increased over 13 miles per M. P. H. From this point on the generator delivers a current having a value of 10 amperes regardless of engine or car speed.
The construction of the unit is clearly shown at Fig. 228. The yoke and field winding assembly shows clearly the hexagon yoke
Fig. 228.—Views Showing Construction of Simms-Huff Motor-Generator..
which makes it easy to mount the device on the engine and at the same time gives a maximum field strength with economy in space and weight. The arnrature is an iron clad drum winding and is perfectly balanced. The complete unit with the cover removed from the end to permit of ready inspection of commutator and brushes is also outlined. The wiring diagram at Fig. 229 shows the application of the complete system to the Maxwell car while the method of attaching the generator to the engine is clearly depicted at Fig. 230.
Fig. 229.—Complete Wiring Diagram of Simms-Huff Starting and Lighting System Used on Maxwell
The unit is connected to the gas engine through a gear reduction in the conventional manner. The starting is accomplished by depressing a starter pedal which provides an interlock between the starting switch and the gear reduction. When contact is made at the starting switch the current flows through the armature and field windings, these drawing approximately 40 amperes from the storage battery to start a 4 cylinder car of 30 H. P. The cranking speed depends upon the ratio of gear reduction and condition of the motor. The starting switch construction is bolted to the left side of the transmission case and the interior arrangement
is such as to automatically connect the two halves of the storage battery in series when starting which means a current of 12 volts, or in parallel when generating, which means a charging current of 6 volts. As applied to the Maxwell engine the machine is geared to the flywheel by a sliding pinion when starting and is driven by the fan belt from the front end when generating.
In common with all systems involving the use of the generator and storage battery together and not having the non-stalling feature, it is essential to provide some means of preventing the bat