Vibrating regulators are of the "constant" current or the "constant-voltage" types. The constant current regulator has a winding of heavy wire which carries the charging current. When the charging current reaches the value for which the regulator is set, the electromagnet formed by the coil and the core on which it is wound draws the regulator armature toward it and thereby separates the regulator points, which are in series with the shunt field. A resistance coil, which is connected across the regulator points and which is short-circuited when the points are closed, is put in series with the shunt field when the points separate. This reduces the shunt field current, causing a decrease in generator voltage and hence current output. As the current decreases, the pull of the electromagnet on the regulator armature weakens and the spring overcomes the pull of the electromagnet and closes the regulator points. This short-circuits the resistance coil connected across the regulator points and allows the shunt field current to increase again, thereby increasing the generator output. This cycle is repeated at a high rate of speed, causing the regulator points to vibrate rapidly.
The action of a vibrating "constant-voltage" regulator is exactly the same as that of the "constant current" regulator, except that the coil is connected across the generator brushes. The action of this coil therefore depends on the generator voltage, the regulator points vibrating when the generator voltage rises to the value for which the regulator is set.
Adjusting Reverse-Series Generators. The regulation of the output of this type of generator is accomplished by means of a field winding which is in series with the armature, and which therefore carries the charging current. These series field coils are magnetically opposed to the shunt field coils, and an increase in charging current results in a weakening of the field flux. A balanced condition is reached at which no increase of flux takes place as the generator speed increases, the tendency of the increased shunt field current to increase the total flux being counterbalanced by the weakening action of the flux produced by the series field current.
To increase the output of a reverse series generator, it is necessary to weaken the opposing series field flux. The only way of doing this is to short-circuit the series field coils, or connect a resistance across them. To decrease the output of a reverse series generator, a resistance coil may be connected in series with the shunt field winding. Neither of these schemes is practicable, and hence the reverse series generator may be considered as a "non-adjustable" machine. Under-charging may be prevented by using the starting motor and lights as little as possible, or by giving the battery a bench charge occasionally. Over-charging may be prevented by burning the lights whenever the engine is running, or leaving the lights turned on over night.
Other forms of regulation have been used on the older cars, but the majority of the cars now in use use one of the four forms of regulation described in the foregoing paragraphs. If adjustments need to be made on some car having a system of-regulation with which the battery man is not familiar, the work should be done in a service station doing generator work.
If generator outputs are changed because of some special operating condition, such as summer tours, the rate should be changed to normal as soon as the usual driving conditions are resumed.
TESTING AND FILLING SERVICE
Every man expects to be paid for his work, since his purpose in working is to get money. Yet there are numerous instances in every line of work requiring work to be done for which no money is received. The term "Free Service" is familiar to every repairman, and it has been the cause of considerable discussion and dispute, since it is often very difficult to know where to draw the Tine between Free Service and Paid Service.
The term "Free Service" might be abolished with benefit to all concerned. In the battery business "Free Inspection" service is a familiar term. It is intended to apply to the regular addition of distilled water by the repairman and to tests made at the time the water is added. Since the term "Inspection" might be Misinterpreted and taken to apply to the opening of batteries for examination, the term "Testing and Filling Service" should be used instead of "Free Inspection Service."
Battery makers furnish cards for distribution to car owners. These cards entitle the holder to bring in his battery every two weeks to have distilled water added if necessary, and to have his battery tested without paying for it. This service requires very little time, and should be given cheerfully by every service man.