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Show THE "SUDDEN" HABIT HARD ON AUTO TIRES ' While it is not proof against abuse, the reat toughness of the rubber used in Federal tread? enables them to stand an amount of mistreatment which wouid send ordinary tires to the junk ijite. said Sales Manager Edmunds of the Browning Auto, & Supply company, local Federal tire distributors, the other day. ilBut,?' continued Edmunds, 11 harsh use of brakes and clutch shortens the life of the very best tires very materially. ma-terially. Sudden starting of a car does not give the rear wheels a chance to 'roll' the friction on the tire is severe. se-vere. "Sudden, hard application of brakes is even worse. It locks the wheels, while the car's momentum drags the tires over the road surface. This of course grinds down the treads very rapidly. Often only one tire is damaged dam-aged in tills way due to uneven adjustment adjust-ment of the brakes. ''The tire-saving method of driving is to control your car- by the throttle and not by frequent application of the brakes. "Never," concluded Edmunds, 'Mock the wheels, except in an emergency.' J it - - ., --. , i - ' isArdamoStk Amplified By an Automobile Expert. If ttioro Is anytbtiis not clear to jou, aHk the nutomoblla editor atiout It. An answer will bo published on the complotlon of the artlclo portuinlug to each section under discussion. 1 Jfl r ) i s J 1' I J p I h U 1 o.'U br Ft& 4 , ) LESSON NO. 29. The Dual System. A preat number of oars are equipped with what is termed the high-tension-dual system, which a a combination of a high-tension magneto and a battory-ignition battory-ignition system, but which has but one spark plug for each cylinder. In this system a batten,- is used for starting the engine, and when the engine has started the switch is thrown, so as to "cut in" the magneto and "cut out" the battery. As a rule, the high-tension magneto will yield a spark at cranking speeds, but. especially with the heavier cars, it is sometimes found neces'iy to supply the battery for starting, ay (he slow revolution revolu-tion of the magneto armature ehait means that the voltage is often so low as not to give the spark. Even where the battery Is furnished the magneto can often be used for starting, especially if the engine be spun when cranking. Let us see what the wiring is. First of all we have the high-tension magneto, the wiring of which Is as shown in Fig. 1. A being the magneto armature. Then we have the battery system, which Is the same as the distributor system as studied in a previous lesson. This system, as you probably remember, has a secondary and primary circuit, the primary circuit having hav-ing as its necessary units a battery, a coil, an interrupter, a switch and a condenser, con-denser, while the secondary has the coil winding, a distributor and the spark plugs. The wiring of this is as shown in Fig. 2. The primary wires are shown by thin lines; the secondary, heavy lines. The problem, then. Is to combine the two sy2tems in as simrle a way as possible, possi-ble, and to have as few duplications of parts as is practicable. Let us see. Will we require two distributors? No, the one will do for the two systems. Will we have to have two Interrupters? Yes, for If the magneto interrupter were to be used for the battery, when the interrupter points open, the current could go through the armature winding of the magneto and so would not be Interrupted, and also it mlsht draw the mnenetipm from the , maqnets. Thus two inti-rvupters arrt nec- ! essary. 1 will' not. how- or. be necessary neces-sary to have- two driving shafts, as thft battery interrupter could He placed on the magneto shnf 1. say, in back of the magneto interrupter. Tlit dual ignition system magnetos are. therefore, designei with a Finele distributor, distribu-tor, but witli two interrupters. In the Fosrh. the battery interrupter is placed Just below the magneto interrupter, wnile in the Kiseman it is placed immediately behind lu Obviously, when we want to use the battery, the magneto must be cut out and battery cut in, and when we want the magneto the reverse is true; while when we want to stop, both must be set so as not to yield a spark. This, of 'nurse, can be accomplished by the use of one switch, though this switch needs must be rath-.-r complicated. Figure 8 gives the wiring of the combined system. I have made the switch all out of proportion pro-portion to the other parts In this drawing, draw-ing, so as to make the tracking of the circuits more simple. In the switch as drawn the two circles represent stationary station-ary narts, while the metal arm, Z, and insulated arm, Y, can be made to revolve. You will notice that the arm Y has on each end a piee of metal or conducting material, as T and V. When the switch is at neutral and engine en-gine Idle, the magneto primary must be connected to the grounded wire, S, and the battery circuit must be open. Let us see if this is so. Tracing the magneto primary, we find It starts on the armature arma-ture M A, then goes out through wire A. from which it can go to the interrupter or through wire B, to switch at R ; it can then go through T to S, and so to the ground. The battery primary will go from the battery, through F, to the switch at O, but, you will notice that U is In such a position that the current cannot get to P, and so this circuit is open. You will also notice that the secondary circuits cir-cuits are broken, as the arm Z is in such a position that the right-hand end is not in contact with either N or M. Let us throw the switch to battery for starting. When we do this we revolve the arms Y and Z In the counter clockwise clock-wise direction, so that they will take the position shown by the dotted lines. As before, the magneto primary will go through wire A, from which It can go to the interrupter or to the switch by way of wire B. You will note that because of the length of T on the arm Y the-current the-current can again go through it from R to S and so to the ground; thus, by preventing pre-venting the interruption of the current, makmg the magneto inoperative. The battery primary will go from the battery to the switch, through wire F, and then, because the arm Y Is now in such a position posi-tion that the metal U is in contact with both O and P, It will go through this to p. then along wire G to the coil, then through H to the battery interrupter, from which it will go to the ground, and rfo back to the battery. Every time the batterv interrupter points are opened a the secondary wiring of the coll W, which will go through wire E to K. then through arm Z (now in contact with It) and then along D to the distributor and so to the plugs, returning through the grounft to S, and along wire 3 and S S to the coil. When the engine 1ms started we swing to magneto by throwing the swjtth so as to revolve the arm Y and Z in a clockwise clock-wise direction, and past the neutral point to the position shown by dots and dashes. You will note that T now is out of contact con-tact with S, and so the magneto primary cannot go to the ground. Thus, when the magneto interrupter points open a high-tension high-tension current will start on the armature, arma-ture, go through wire C to M of the switch, through arm Z to L and so again through wire T) to the distributor and thence to the plugs. U being out of contact con-tact with P now, the battery circuit will be open and the battery system bo inoperative. in-operative. The switch and coil are always built as one unit, and on the Bosch coil is printed a diagram showing where the wires go. On the Eiseman, however, the terminals are simply numbered and you must have their instruction book or 'know how to wire up the battery, coil and magneto, j Figure 4 gives a wiring diagram of the ; Eiseman dual system, taken from the j Eiseman catalogue. I have lettered the I wires to correspond to letters of the wires '. in drawing Fig. 3. Practice tracing the circuits in Fig. 4, when switch is at neutral, neu-tral, at battery and at magneto. By observing the picture of the magneto mag-neto you will notice that the only change in it from the plain high-tension magneto, mag-neto, outside of the addition of the battery bat-tery interrupter, is that instead of the current running direct from the secondary collector brush, H M. to the distributor, it is first run through wire C -to the switch and then back through the wire D. Here is a little problem. Suppose the switch and noil wore ruined, and you vonld not replace them for a few weeks, but wanted to use the car in the meantime, mean-time, what would you do? Tho last and the third paragraphs will give a clew to the solution. |