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Vol. 2. No. 24. NEW YORK, August 25th, 1906 Single Copies 10c.

MAKE-AND-BREAK VERSUS JUMP-SPARK
By K. J. Williams E. E.

"Which system of ignition do you consider the best, jump spark or make—and—break ? And why?"

These are questions often asked, and interest many persons in contact with the explosive type of engine.

While acknowledging the simplicity of the make—and— break, both have their advantages and disadvantages.  Both principles of operation have been utilized for years in the electric gas—lighting industry, and were considered even terms as to reliability. This is not a guarantee that even terms exist with both these principles of ignition in the gas—engine industry, an(1 although it has often been claimed that the simplest apparatus of any kind is the best, nevertheless, it is well to compare the two systems in an endeavor to note the existing differences.

Without the aid of a coil, no spark can 1)e produced that is large enough to ignite the gas. when using batteries to generate the current for either system. The make-and break coil consists of one continuous winding of coarse insulated wire wound over a soft—iron core. When the electricity passes through the coil, and the circuit is suddenly broken—that is. if two wires are separated after being connected—a spark of high intensity follows the break or gap for a very short period of time. To produce the spark in the cylinder a mechanical motion is imparted to one electrode or end of the wire. as it might be, at the proper point in the revolution. The moving electrode touches the stationary point, to permit the current to flow, forming a circuit, just before it is broken.

Make-and-break spark as ordinarily utilized requires a large voltage as generally compared with jump-spark, and uses more. at each time of ignition or contact, because the contact is made during a certain length of the revolution.  This makes the make—and—break system stem utilize a larger amount of battery power per hour than the jump— spark, as will be explained  further on in this article.

The spark generated by using the make-and-break system is. however, larger and hotter than the jump- spark. Properly designed, an advancing arrangement can be made to advance and retard the spark through the same useful portion of the revolution as jump—spark,  but very few designers seem to care to arrange this important feature of the make-and-break system being satisfied to set the spark at one point in the cycle, and generally not being able to change unless the engine


is stopped  The hammer type of make-and-break has given very good service. The power to be derived from a gas engine is proportionate to the proper combustion of the gases.

Make-and-break gives the hotter spark. consequently more power because it ignites the gas more quickly. It gives a very instantaneous ignition and less advance is required. because the action is quicker than jump— spark. Then again, this system has only one circuit and is easily understood  by the novice and appeals very readily to the beginner.

Jump-spark coils utilize two circuits, one a high tension or voltage, the other a low voltage battery circuit. The coil is also made up of a vibrator, condenser, primary winding and secondary winding and the system consists,  in addition, a timer or commutator and spark plug. Various windings and systems of connections are in vogue, generally placed inside the coil case, to derive the same results. The contact of the timer causes the current to flow through the coil, magnitizes the core, attracts the vibrator, and forces a high voltage through the secondary winding.  Jump-spark it is claimed, lags at high speed, owing to the magnetization and attraction of the vibrator. Less current is used owing to the vibrator breaking the circuit many times during contact of the timer, than make- and-break, therefore batteries last longer with jump- spark

High-tension wires are necessary in the jump-spark ignition leading from the coil to the plug and unless using a waterproof cap to protect same from spray, when used in the open power boat, a short circuit in the sparking circuit is liable to occur.

The principle trouble with jump-spark is its liability to leak current through faulty insulation. The secondary or plug circuit emits such a high voltage that the spark leaks anywhere, and generally at the least suspected place An inspection of the wiring system should be made often, preferably  in the dark, when a small leak in the secondary circuit can be readily located.

Another great trouble is from sooty plugs, because the sparking points are stationary and collect oil, etc., which sooner or later, foul or carbonize them to such an extent that the spark refuses to jump the gap. The high voltage often perforates the mica insulation, or the heat cracks the porcelain and allows the spark to jump through the insulation instead of across the points. The danger of shock by coming in contact with the plug or coil-binding post is greater, and the shock received

 

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more severe, but can be easily warded off by using common sense. Testing out the system for trouble may be a little more intricate with jump—spark but easily under stood, when the principle  is understood. The advantages in favor of this system is that it can be advanced in the cycle while the engine is in operation, by the very simple method of advancing or retarding the timer or commutator on its shaft.

Comparing the two systems. jump-spark advantages are its accessibility to advancing and retarding; consumes less electricity; the strength of the battery can be determined by the vibrator's action; requires no engine apparatus such as rods, cams, springs, levers, etc.; the plug screws into the cylinder leaving no possible means for loss of compression to be traced to this source; jump-spark ignites the gas more readily in starting because the points are so small that heat enough is generated to warm the gas at the flame.

The disadvantages are:  Leaks in secondary or high tension circuit; cracked or fouled plugs; a positive current in the primary circuit is no guarantee of a spark occurring at the plug points; liability of burning out the secondary winding if too many batteries are in circuit; lags slightly at high speed requiring a further advance than make-and-break; spark-plugs carbonize; is effected by dampness or moisture, such as rain or spray; extreme high compression blows out or insulates the spark.

Make-and-break advantages are: Its simplicity, using one circuit; a test of the battery circuit is a test of the sparking circuit; ignites the gas quickly and


thoroughly; low voltage circuit; not readily effected by spray or rain ; coil not easily burned out.  Its disadvantages are: Working parts in the cylinder firing chamber; loss of compression sooner or later through the movable electrodes bearing; inaccessible generally, although not always, to advancing the spark; requires setting regularly; sparking points wear; springs cams, levers. rods, etc., requires an unnecessary amount of battery current.

The claim of unnecessary amount of battery is better explained in considering that ten times more current or the time of ignition is ten times longer at 100 r.p.m. than at 1,000, with a waste of 9/10th of the battery power a the former speed

With these advantages and disadvantages set forth the writer leaves the problem with the reader for solution as a personal opinion need not be expected or considered necessary.

This document was converted to text with OCR software.

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