The Titan Post Seal is shown in Fig. 293. A soft rubber gasket (G) is slipped over the post, and rests on a shoulder (F) on the post. The cover has a channel which fits over the gasket and prevents the gasket from being squeezed out of place when the cover is forced down on the gasket. The post has two projections (DD), as shown, the lower surface of each of which is inclined at an angle to the horizontal. A lock nut (H), which has corresponding projections (IJ) is slipped over the post as shown at (0), and is given a quarter turn. The top surfaces of the projections on the lock-nut are inclined and as the locknut is turned, the projections on the post and nut engage, and the cover is forced down on the gasket (G). To lock the nut in place, a lock washer (L) is then slipped over the post, the projections (MM) fitting into spaces (KK) between the projections on the post and nut, thus preventing the nut from turning. A special wrench is furnished for turning the lock-nut. The cell connectors rest on the tops of the lock washers and keep them in place.
The overhauling of Titan batteries should be done as described on pages 328 to 374.
SECTION 3.
CHAPTER 17
FARM LIGHTING BATTERIES SPECIAL INSTRUCTIONS
Although the large Central Station Companies are continually extending their power lines, and are enlarging the territory served by them, yet there are many places where such service is not available. To meet the demand for electrical power in these places, small but complete generating plants have been produced by a number of manufacturers. These plants consist of an electrical generator, an engine, to drive the generator, and a storage battery to supply power when the generator is not running. The complete plants are called "House Lighting," "Farm Lighting," or "Isolated" plants.
The batteries used in these plants differ considerably from the starting batteries used on automobiles. The starting battery is called upon to deliver very heavy currents for short intervals. On the car the battery is always being charged when the car is running at a moderate speed or over. The battery must fit in the limited space provided for it on the car, and must not lose any electrolyte as the car jolts along over the road. It is subjected to both high and low temperatures; and is generally on a car whose owner often does not know that his car has such a thing as a battery until his starting motor some day fails to turn over the engine. All starting batteries have wooden cases (some now use rubber cases), hard rubber jars, and sealed on covers. The case contains all the cells of the battery. Automobile batteries have, therefore, become highly standardized, and to the uninformed, one make looks just like any other.
Farm lighting batteries, on the other hand, are not limited as to space they occupy, are not subjected to irregular charging and discharging, do not need leak proof covers, and are not called upon to delivery very heavy currents for short periods. These facts are taken advantage of by the manufacturers, who have designed their farm lighting batteries to give a much longer life than is possible in the automobile battery. As a result the farm lighting battery differs from the automobile battery in a number of respects.
Jars. Both glass and rubber are used for farm lighting battery jars, and they may or may not have sealed-in covers. Fig. 294 shows a glass jar of an Exide battery having a hard rubber cover, and Fig. 295 shows a Prest-O-Lite glass jar cell having a cover made of lead and antimony. Unsealed glass jars, such as the Exide type shown in Fig. 324, generally have a plate of glass placed across the top to catch acid spray when the cell is gassing. Each jar with its plates and electrolyte forms a complete and separate unit which may easily be disconnected from the other cells of the battery by removing the bolts which join them. In working on a farm lighting battery, the repairman, therefore, works with individual cells instead of the battery as a whole, as is done with automobile batteries.