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Show By an Automobile Expert. If there is anything not clear to you, as'i the automobile editor about i-An i-An answer will to paUied on the completion of the articles pertaining to each section under discussion. LESSON NO. 37. The Starting Motor. We have seen how when a loop of wire is made to revolve in a magnetic field, a current of electricity will flow in tne wire. Now the reverse action will ulo take place; that is, w-hen a current of electricity U made to flow through the loop of wire ill the field, the loop will be made to revolve out of the field. In the first case (the generator) gen-erator) by revolving the loop of wire in the field, current, will flow through ; tv,o Mecoiol cae ft.ho mo tor), by making curreut flow through the wire the loop is made to revolve out of the field. On the latter principle princi-ple all electric motors are designed. Thus an electrical generator can be made to act as a motor, or a motor as a generatc-r. . There is, however, a practical difference differ-ence in tie two machines. The proportions propor-tions are different, Jut the greatest difference is in the wiring of the field coils, in the last lesson, you were shown how the field coils of tue generator gen-erator are shunt wound or compound wound. The motor, however, is practically prac-tically always series wound; that is, the current as it comes from the bat- t-Mi j L. V i .... .-I,...," t- . rR-!) W-llT I tiB awtw I I I "Tr V. m ' ttrivrng Pimm lX Sbott ItirlMj Smtdi J fciv first passes through the field i coils, then through the armature windings, wind-ings, and then back to the battery. Thus you see the field coils and armature arma-ture a're in a series. If requires a high ampeYage to give the motor the required turning power to ciank the heavy engine, ranging, from 120 to bOO, depending upon the size, of the motor, the size of the engine and the gear ratio between them. It is important to remember the above, as not only does it show how the hatterv is quickly discharged when the startinc motor is used (as explained in the ba'tterv lesson), but it show6 why t care, must be taken not to get any other units of the starting and lighting system, in series with the starting motor, mo-tor, and whv the wires deading to the starting motor, and the starting switch must be large. The generator, lights, ignition ammeter, etc., are all built to work on a low amperage, seldom higher than 15, and should the high amperage motor current flow through them, they would instantly be burned out and ruined. The above mistake is seldom made where th-i generator and motor are two separate units, but is very ofler made where thev are built together. Many a man lias 'tried tp install an ammeter on his ear. to tell him the condition of the charging of his battery, and has cotten it in"series with the motor, with the result that it was instantly burned out. The fact that a motor will act as a generator, or generator as a motor, is utilized in many cases, the two instruments instru-ments being built together, when so built together it is kuown as a motor-generator, motor-generator, and the car is said to be ..,;, -n-itl, a sinrrlp unit, while when the two are separate, it is said to be a two-unit system. The designs of the motor-generators vary. In some cases, the machine has two commutators, two armature windings wind-ings and two field windings, others have but. one commutator, but two sets of brushes, while still others have only-two only-two field windings; a series, to be used when the machine acts as a motor; and a shunt, to be used when it acts as a generator. The motor seldom gives trouble, what troubles it is subject to being about the same as those of the generator. Placing too great a load upon the motor, mo-tor, asis sometimes done by using the : motor while the car is in gear, so that, i in addition to cranking the engine, the I motor must drive the car, may result m I the motor overheating, due to the high I amperage, so that the insulation be-i be-i comes burned. When this happens the ' motor is said to be burned out, and must be sent to the factory for repairs. There are many wavs of connecting the motor to the' engine. The connection connec-tion must, however, be made iu such a wav was to disconnect the motor armature arma-ture aud the engine the moment the engine en-gine starts. The connecting and disconnecting dis-connecting of the motor and engine, has been one of the big problems m the development of the electrical starting start-ing svstem, and the failure of the devices' de-vices' used is still often the cause of ''trouble." About ?0 per cent of the cars have gear teeth cut on the flywheel of the engine, and have a pinion gear connected con-nected to the motor. When starting this pinion gear is made to sliue tor-ward tor-ward and into mesh with the flywheel gear, and when the engine has started the pinion gear slides back and out of mesh. This seems simple enough, but one creat problem presents itself, I namely, sometimes the teeth of the Pinion, instead of coming into the hollows hol-lows between the teeth of tiie flywheel will come against the teeth and so cannot can-not get into mesh, no matter how hard ! the starter pedal be pressed. To over-i over-i come this difficulty many makers arrange ar-range to have the pinion slowly revolve as it slides forward. This is accom-plisle.d accom-plisle.d 1-t letting but a little current yet to tlie motor at first, so that it re-v,,i.-r- lo--lv r-t f'rt. If a rei-i nn fr is plac'M between the battery and the motor only a little current will get to the motor. The liiusc.r.tioii shows what happens as the stariei pedal -s rre?ed. lu Fi. A. wmcn t-noHs. ibe position of switch and pinion when at rest, you will note that the pinion 0 is away fi-.jm. Cie ge.ir or the f:-wheel, while t tie contactor of the swit -h P-P is not touching the fingers of the switch. rig u re !; shows wh.-.t happens when the starter pci.nl is fiiglflly pressed. The i.iuiou (i is still awav from the flvv.heel. Ivat the conta- tor is in con-jta'ct con-jta'ct with the iiigeis ot the switch. I Current, from the balterv will now flow I . . . l' 1- ll .1.,... n rrom it, inrougn vvi.c i to e-, men iy j F, across the contactor, then through the resistance K, and so through M to the motor, and then back to the batter.-. Thus the motor wiil revolve slowly and so make tho pinion revolve slovvlv. As the pedal is pressed down farther, the condition shown iu Fig. C is obtained. ob-tained. Here, you will notice, tho pinion pin-ion G is partly in mesh with tho flywheel, fly-wheel, while tlie contactor of the switch is out of contact with tho fingers. Pressing the pedal down farther will pull tho gear into full mesh, and, finally, bring the contactor into the ' position shown in Fig. 0. Now the I full current will go to the motor and i the engine will be upua vigorously , . When the foot is taken off the pedal, the return spring will bring the system back to the position shown in Fie. A-' A-' In manv cases the pinion shitting rod, instead of being connected to the contactor, is a separate rod, and has its separate lever. Where this is the case there usually is a, turn-buckle or -other length-adjusting device on it. the length of this rod must be adjusted so that the condition shown m the illustration illus-tration are obtained. Sometimes by the turn-buckle becoming loose and. revolving, re-volving, the system is put out ot adjustment. ad-justment. When this happens the tarter will work today, but not tomorrow, tomor-row, depending on whether the pinion teeth hit the gear teeth or gear not-1 10 Tho fingers of the switch also often become weak or worn and do not make contact, .in which caso tho result will also be s.s above. ... A most excellent device, kttowii as the Peudi.-c drive, has recently been brought out, in which the pinion is made to revolve and brought into mesh automoticallv. This is shown m Fig. E Here the pinion, instead of being positively connected to the motor, is set on a ' screw. As tho motor revolves, the screw will revolve, and the pinion, because of its inertia, will screw tor-ward tor-ward on this screw until it is in mesh. When the pinion is m mesh, it win come to the shoulder of the screw, and so revolve with it. In -the illustration the screw, like the pinion, is not positively posi-tively driven from the motor, out by the pinion spring. In this way the starting drive of the flywheel is cush-ioned. cush-ioned. , . . While this drive works almost perfectly, per-fectly, the teeth of the pinion ivill cnmPtiiTiPn lock arrainst the teeth ot tlie flvwheel gear. When this happens the remedy is to crank the engine a little bv the hand crank, or the car can be put into hii'h gear, and, while the ignition igni-tion switch is off, pushed back and fce-th a bit. This will crank the engine and so release the pinion. |