Fig. 1,192.—Dayton launch lighting outfit. It consists of an "Apple" dynamo, switchboard and storage battery. The dynamo is fitted with a bevel friction drive governor. The dynamo gives a three ampere charging rate on a six volt battery at its normal speed of 1,050 R. P. M. The switchboard is provided with a combination volt-ammeter which shows the voltage of the battery, the ampere charging rate of the dynamo and the ampere discharging rate of the battery. The automatic cut out in the back of the switchboard automatically severs the connections between the dynamo and the storage battery when the engine stops and so prevents the storage battery current running back through the dynamo when the dynamo is not generating current. A 6 volt, 60 ampere hour battery, consisting of 3 five plate units connected in series, is used with the size dynamo shown in the illustration.
The power for running such a dynamo is obtained in various ways. The dynamo or charging booster may be belt driven or arranged on an extension of the armature shaft of the main dynamo; again, it may consist of a single armature with a double winding ([fig. 1,191]), or a motor and dynamo coupled together on one bed plate as in figs. 800 and 805. Boosters may be divided into several classes as follows:
1. Series boosters;
2. Shunt boosters;
3. Compound boosters;
4. Differential boosters;
5. Constant current boosters;
6. Separately excited boosters.
Series Boosters.—The series booster acts so as to compound the battery, and tends to maintain a constant voltage on the line, whatever the load may be. Its operation depends on the fact that the dynamo voltage must rise and fall with the load. It can, therefore, be used only with a shunt dynamo or its equivalent as the source of supply.
Ques. What use is made of the series booster system?
Ans. It is suited to power, but not to incandescent lighting purposes, being similar in operation to a floating battery. It is not extensively used as the other types give better service, under the same conditions.
