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
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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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