Electric versus Other Ignition Systems.—En gines that burn gas or gasoline can be operated best by some kind of an electric ignition system.
A wipe spark gives the best results when used with large gas and gasoline engines, since neither the speed nor the compression is very high.
Where a jump-spark system is employed in which the spark is set up by a battery and a spark coil, dry cells will not stand up long under the strain, and if possible you should put in a storage battery, or, better, a magneto.
For a motor boat or a small stationary engine a dry battery will serve in a pinch for energizing the spark coil, but the engine will never deliver its full power when it is used.
Nearly all motor cars and many motor boat en gines are equipped with a circuit breaker spark-coil system, or distributor system, as it is called; in this ignition apparatus a storage battery is used to energize the spark coil, but the better makes of mo bile engines are also fitted with a high tension mag neto and this gives a good hot spark.
A magneto is far less troublesome on stationary engines than any kind of a battery operated spark-coil system, but while its initial cost is higher, it is well worth the difference in the price. On hand-started gas and gasoline engines an oscillating magneto is better than a rotating one, because the armature of the former is only turned through a very small arc past the poles of the magnet by a pair of stiff springs, and, consequently, it delivers a hot spark the first time you turn the flywheel over. Oscillator mag netos are not suitable for high-speed mobile engines, but on medium-sized stationary engines they give very satisfactory results.
Where crude oils furnish the fuel a semi-Diesel engine, that is, one fitted with a hot ball, or bonnet, or a straight Diesel engine, in which the charge ig nites automatically, is the proper kind to get, for it takes a very hot cylinder to change these fuels into gases that will burn and not leave behind a residue.
Kinds of Lubricating small station ary engines a simple oil-cup drip feed can be used, but a splash lubricating system will give better serv ice, while in larger engines the best results are ob tained by the force feed system.
How to Use the Power of Your Mechanical Way.—In motorcycles, motor cars, motor boats, and airplanes the engines drive the propeller shafts either through clutches and transmission gears, through clutches alone, or by being directly connected, and that is all there is to it, as far as you are concerned. But on the farm, things are very different, for there may be a dozen distinct ma chines you want to drive with your engine.
Again, occasionally, you may want to use your engine in any one of a number of places and under various conditions, and you must think about all these details before you invest your money in one. Where an engine is to be moved about it can be set on a skid if it is a small one, or it can be mounted on wheels, as shown in Fig. 36, if it is too heavy for two men to carry about.
Where machines such as corn-shellers, circular saws for sawing wood, pumps, cream separators, lathes, grind-stones and the like are to be run by a stationary engine, the pulley of each one can be of such a size that it can be belted to the engine when you want to use it, though for some machines a countershaft will have to be used to decrease or in crease the speed that is required.
When a number of machines are to be thus run by an engine it will save time, trouble and expense to fit up a regular shop and use a line of shafting so that any machine can be shifted in or out of gear, or two or more machines can be operated at the same time.
The Electrical Way.—If your engine is to be used to drive a dynamo for generating an electric current, the crankshaft can either be coupled direct with the armature shaft or the engine can be belted to the dynamo, just as it is with any other machine.
Now, an electric current generated by a dynamo is useful in the house and on the farm in three dis tinct and wholly different ways, and these are (1) for lighting, (2) for heating, and (3) for power.