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| Make and Break - what is? Interesting... |
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narrabay
Advanced Member
Username: narrabay
Post Number: 39
Registered: 02-2016
| | Posted on Thursday, March 17, 2016 - 02:59 pm: | 
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The vid is not a 1-2 cyl but the principles apply. Still learning about the topic. But at least I know that a make-n-break ignition is not the same as hit-n-miss engine (which governs not with a throttle, but turning off and on the intake valve as needed to reach governed speed as regulated by a centrifugal 'latching' mechanism)
The make and break *seems* to be a low voltage spark, and in the video below the "spark plug" is actually a switch inside the combustion chamber. I wonder if this is the norm? What else characterizes make-n-break ignoition system?
I do understand magnetos coil/breaker points systems, and modern electronic systems to time and generate a spark.
Here is the video in two parts, its really a masterpiece of work: (it starts off slow but gets really good)
Part 1:
https://youtu.be/egbCVxAKvX0
Part 2:
https://youtu.be/KZyuCpoXYgU |
miro
Senior Member
Username: miro
Post Number: 858
Registered: 11-2001
| | Posted on Thursday, March 17, 2016 - 05:11 pm: |
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First off, the voltage used by the MaB ignition is low voltage - 6 - 12 V.
You are correct there is a contact inside the cylinder. There is a fixed part, and the second part is on a small shaft that is electrically insulated from the body of the cylinder going out to the actuator.
Just before the spark is needed ( based on timing) the contact closes, allowing electrical current to flow and then when the spark is needed, the contact opens, creating the spark, thus igniting the fuel / air mix. Usually there is a fairly large coil in series with the battery so there is good spark, when the contact opens.
There are any number of ways to actuate the closing and opening of the contact - each manufacturer had their own ideas.
One big advantage is that the engine ignition is not shorted out by water dripping all over the ignition.
The disadvantage is the mechanical system ( and lubrication) needed to make it work correctly, plus there is a limitation on how much variation you get for timing. There is also the combination of electrical and mechanical delay before the spark occurs.
The system was mainly used on slow speed engines.
Miro |
ernie
Senior Member
Username: ernie
Post Number: 2234
Registered: 01-2002
| | Posted on Thursday, March 17, 2016 - 06:41 pm: |
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Just to clairify it isn't a spark. It is an arc.
Yes there is a difference.
A spark happens because the voltage builds to a point that it will jump a gap to the other side of the circuit. Usually ground. Nothing is happening electrically till the voltage builds to a point high enough to jump the gap.
Make and break creates an arc. The points close causing current to flow. When the points snap open the circuit is interrupted and an arc occurs.
By the way on 99% of all M and B ignitors the movable point is usually the ground side. The stationary point is the insulated one. |
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