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Show Aidomofcle Simplified LESSON NO. 73. Wiring Diagram. Every owner of a car which has a starting and lighting system should have a wiring diagram of the electric system, and should not only have studied it, so as to be able to read it in case of need, but shoulfl. keep it in the car. A wire may become detached, and often, even experienced ex-perienced mechanics will be at a loss to know where it belongs unless guided by the wiring diagram. As a- rule, the wiring diagram is given in the instruction book of the car, or in a special instruction book furnished by the makers of the electrical equipment. If you have not such a diagram, it would be- well to write to the makers, preferably prefer-ably of the electrical system, for one. In all wiring diagrams, for space sake, certain symbols are used to indicate the various units and devices, and it is necessary neces-sary to know the meaning of these symbols sym-bols in order to be able to read the diagram. dia-gram. The same symbol is used by all makers and all diagrams to indicate certain cer-tain of the devices and methods of wiring, wir-ing, but for others, such as switches, interrupter points, automatic contacts, there is no unform symbol. In the upper portion of the illustration I give a list of the symbols generally used, and. where different symbols are used to indicate the same thing. I give those used by four of the makers whose equipment is the most often found on the automobile. Referring to the illustration: No. 1 denotes a positive terminal and No. 2 a negative terminal. In connecting connect-ing wires to the battery, generator or motor, great care must be taken to connect con-nect the positive of the battery to the positive of the motor or generator, as shown by the diagram. When replacing spectively, and tail by a T in the circle. In addition to the above, the horn, interrupter, in-terrupter, distributor and other devices and some of the above are shown in different dif-ferent ways, but their name is usually printed under them. i Having seen the meaning of the symbols used, let ut. trace the various circuits in a diagram, as the one shown, which is that of the Delco, which is used on the Buick models D 44, 45, 46 and 47. First, we must determine how many circuits ther are in the system. Thus, there usually are the motor circuit; the generator circuit; the ignition circuits (primary and secondary), and the lighting circuits. If there is trouble in one of these circuits cir-cuits it is only necessary to tri'.cp that particular cricuit. However, a short circuit cir-cuit in another circuit, between the battery bat-tery and the units, will aflect other circuits, cir-cuits, but in this case the- trouble will show in more than one circuit. The diagram shows the condition when the car is at rest, engine stopped and tights out. In starting the engine the first tiling we would do would be to pull out the ignition switch button D. The current would then flow lrom the battery to the point F. The motor brush B being up. it cannot go to the motor, and so w ill go up to the ammeter,, then, to the point 3, across the switch to " and 4. Wo are tracing the ignition circuit now. and find the ignition coil connected to' 4, so will ignore 2 and find that the current will go to the ignition coil, through the primary coil, then to H of the interrupter, across the points, and then through the ground to the battery. The secondary will start on the coil (fine lines), go to the distributor, thence to the plugs, returning through the grounded wire A. The condenser is con- v- y r g Y 7m. f I ' '-ihSii o 4 i a battery after ! charging, the negative or positive terminal is often grounded where the other should have been. You should observe how the battery is connected when taking it out, or refer- to your diagram dia-gram when replacing. No. 3 represents a battery- either of dry cells or storage. No. 4 represents a battery of dry cells. No. 5 represents a storage battery; No. 6 represents a grounded wire, that is, a wire attached to some metal part of the car. No. 7 indicates a condenser. .No. S shows different symbols for a generator. No. 9 shows different symbols for the starting motor. ' No. 10 shows different symbols for a switch. No. 11 represents fuses. No. 12 shows different symbols, used to indicate contact points, such as interrupter in-terrupter points, automatic cutout points, vibrator points, etc.' No. 13 shows the symbols for a coll wrapped about an iron core, as those used on cut-outs, regulator-s, motor or generator, gen-erator, fields. When of heavy black lines it denotes that a high amperaee or voltage current, as in the starting motor field, passes through them, while if of light lines, the amperage is low. No. 14 represents the ignition induction induc-tion coil. The 'heavy lines usually indicate indi-cate the primary coil and the lighter the secondary- .No. 15 represents a resistance coil. No. 16 represents crossing wires which are not connected and are insulated from one another. - No. 17 represents connected wires. No. IS represents lamps. Generally, the headlights are indicated by an H in the circle, side- or dimmer by an S or D re- nected in parallel with the interrupter so as to prevent sparking at the points. The ignition now being ready for starting, start-ing, we step on the starting pedal. This will bring the motor brush in contact and raise the generator brush. The current cur-rent will now flow from the battery to the motor also, which will now crank the engine till it starts. The engine having started, the foot is taken off the pedal, thus raising and disconnecting the motor brush, and lowering low-ering and connecting the generator brush. The generator will now generate current, which will go through -the wire (G to the point (2), and then across the switch to 3 or 4. If the voltage of the generator is greater than that of the battery, and there is more current than is needed by the ignition, this excess will go to the battery by way of 3 and the ammeter, and so charge the battery. When a light switch, 5, 6 or 7, is. thrGwn on. the current will come from the point (3), through the current breaker (the purpose of which is to break the circuit automatically in case of a short circuit, like a Rise), thence to the switch, the light and through the ground to the battery bat-tery or generator. You will note that the point (3) Is connected con-nected to both the battery and the generator. gen-erator. Thus when the engine and, therefore, there-fore, generator is idle, the battery will furnish current for the lights, while" when the generator is working it will furnish the current. If the generator makes less current than is needed by the lights and ignition some will also come from the battery. . Jf it makes more, the excess will go to the batterj"- ,It would, be well for readers to get out their wiring diagrams and trace the circuits cir-cuits as above.. This not only will prove instructive, but entertaining as well. |