Ignition Coil.—The ignition coil, which is contained in a separate housing, forming part of the distributor unit, is constructed for 12 volt service and operates directly on the starting and lighting circuit. The coil housing is attached to the distributor base by means of four screws and serves also as a cover for the automatic advance compartment. The high tension terminal located on the coil housing is designed to provide a safety spark gap, as well as to act as a binding post for the high tension cable which connects the coil to the distributor head.
Breaker Box and Distributor Head Assembly. ([Fig. 64]).—The breaker box and distributor head assembly is mounted in an upright position near the center of the distributor base and is secured in place by a large-headed screw in the vertical portion of the base. This screw projects into the annular groove in the vertical shaft bearing sleeve, thereby preventing the breaker box assembly from becoming detached from the distributor base and yet at the same time permitting it to turn freely from side to side. The short lug projecting downward from the manual control lever on the breaker box extends into the round hole near the middle of the distributor base and acts as a stop to limit the travel of the breaker box.
In case it should become necessary to remove the breaker box and distributor head assembly, the distributor head should first be detached from the breaker box and then, with the breaker box in the position of full retard, the exact location of the distributor rotor should be marked accurately on the edge of the box. This mark should be made with special care, because it has to serve as the sole guide for the correct position of the vertical shaft when the assembly is put back in place again on the distributor base. Moreover, while the breaker box assembly is separated from the base, the horizontal shaft in the base must not be turned from the position it occupied at the time when the location of the rotor was marked. If either of these precautions is neglected, the correct relationship between the several moving parts of the system will be likely to be disturbed to such an extent that the complete retiming of the distributor will become necessary.
Fig. 64. North-East Breaker-Box
Condenser.—The condenser, shunted across the breaker contacts to absorb the inductive surges that occur in the primary circuit at each interruption, serves to intensify the effect produced in the secondary circuit by these interruptions, and also to protect the breaker contacts from injurious arcing. It is contained in a sealed case which protects it against possible external injury, and is located in the breaker box close to the breaker contacts where its maximum effectiveness is obtained.
Being very substantially constructed, the condenser ordinarily requires no attention. If for any reason it should become inoperative, the best course is always to replace it with a new one, because condenser repairs are not economically practicable. The entire condenser unit can be easily removed, whenever desired, by disconnecting the two condenser leads from the breaker box binding posts, and then unscrewing the two nuts on the under side of the breaker box that hold the condenser case in place.
Breaker Contacts.—The breaker arm, which carries one of the two breaker contacts, is mounted on a pivot post from which it is thoroughly insulated by a fiber bushing. The helical spring, which is attached to the lug at the pivot end of the arm, holds it normally in such a position that the breaker contacts are kept closed. But the fiber block near the middle of the breaker arm lies in the path of the breaker cam and is consequently struck by each lobe of the cam as the vertical shaft revolves. Each of these blows from the cam cause the breaker contacts to be forced apart, and thereby produce the necessary interruptions in the primary circuit. The second contact is carried by the stationary contact stud, which is adjustably mounted in an arched support. With this stud properly adjusted the difference between the contact points when they are fully separated by the cam, is twenty thousandths of an inch (.020″).
If it should ever become necessary to renew the breaker contacts, a complete replacement of the entire breaker arm and the contact stud assemblies will in general be found to be the most effectual method of handling the work. The breaker arm can be removed by simply lifting it off its pivot bearing after its pigtail has been disconnected from the breaker box binding post. The spring attached to the breaker arm lug will slip off of its own accord as soon as the arm is raised sufficiently from its normal position. After the breaker arm has been taken off, the stationary contact stud can be removed by releasing its lock nut and unscrewing it from its support. To replace the breaker arm it is merely necessary to insert the lug in the spring, and then, with the spring held taut, to push the arm firmly down upon its pivot post until it snaps into position.
Breaker Cam.—The breaker cam, by which the interruptions in the primary circuit are produced has four projections on its working surface, so spaced that one of them strikes the breaker arm and causes the breaker contacts to be abruptly separated each time a spark is required. The cam is held in place on the upper end of the vertical shaft by means of a slotted nut and set of special lock washers. It should never be disturbed if avoidable, because its accurate setting is absolutely essential to the correct operation of the entire system. If, at any time, however, its position should become altered accidentally, it must be carefully reset at once in accordance with the timing directions given later on.