Fill in the Blanks
1. 36
2. laminated steel
3. neutral
4. after
5. full-register
6. E-gap
7. impulse coupling
2. laminated steel
3. neutral
4. after
5. full-register
6. E-gap
7. impulse coupling
8. shower of sparks
True or False
1. true
2. true
3. false
4. true
5. false
6. false
7. true
8. true
Knowledge Application
1. A magneto has its own source of electrical energy, and it is not dependent upon the battery.
2. The capacitor minimizes arcing at the breaker points, and it speeds up the collapse of the primary current as the breaker points open.
3. A compensated cam is a special cam used in magnetos mounted on high-performance radial engines. The cam has one lobe for each cylinder, and the lobes are ground in such a way that the breaker points open when the pistons in the different cylinders are the same linear distance from top center.
4. These numbers are the sparking order of the magneto, not the firing order of the engine.
5. The primary circuit is connected to ground.
6. Low-tension magnetos are used on aircraft that fly at high altitudes where there is a problem with flashover in the high-tension magneto distributor.
7. The low-tension ignition system has only one coil in the magneto, and it uses a carbon-brush-type distributor. Low voltage is distributed to high-tension transformers that are located on the heads of each cylinder. A high-tension magneto produces high voltage in the magneto coil, and it is sent to the correct spark plug by the built-in high-voltage distributor.
8. A shielded spark plug that has a recess in the shielding in which a resilient grommet on the ignition lead forms a watertight seal.
Multiple Choices
1. b
The magneto magnetic circuit consists of a permanent multi-pole rotating magnet, a soft iron core, and pole shoes.
2. a
A magneto is essentially an AC generator whose output is determined by the speed of the rotor and the strength of the permanent magnet.
To test the strength of the permanent magnet, the magneto is mounted on a test stand and driven at a specified speed.
The breaker points are held open and the primary current is measured with an AC ammeter.
3. b
By definition, the E-gap angle is the number of degrees beyond the neutral position of the rotating magnet at which the breaker contact points open.
It is at this point that the flux change is the greatest and the primary current is the greatest.
4. a
The greatest flux density in the magnetic circuit of a rotating magnet-type magneto occurs when the magnet is in its full-register position.
In the full-register position, the magnet is fully aligned with its pole shoe faces.
5. b
Internal timing of a magneto is the timing of the opening of the breaker points relative to the position of the rotating magnet and the distributor rotor.
Internal timing is best accomplished while assembling the magneto before it is installed on the engine.
6. c
A high-tension ignition cable is “shielded” when it is routed inside a flexible metallic conduit or braid.
The electromagnetic field radiating from the conductor during the time the spark is occurring at the spark plugs, is picked up by this shielding and carried to ground so it cannot cause radio interference.
7. b
If the gap of the breaker points is increased, the spark will occur early (it will be advanced). And, because the magneto will be out of time internally, the spark will also be weak.
8. a
Safety gaps are in the secondary circuit of a magneto to protect the insulation of the secondary coil.
If there is an open in the secondary circuit (such as could be caused by a lead being left off a spark plug), the voltage will build up high enough to cause a spark to jump across the safety gap rather than allowing the voltage to rise high enough to damage the secondary coil insulation.
9. c
When the timing marks are aligned while internally timing a magneto, the magnet is in its E-gap position.
The E-gap position is a few degrees of magnet rotation beyond its neutral position, in the direction of normal magnet rotation.
10. c
The breaker points in a magneto begin to open when the rotating magnet is in its E-gap position.
The E-gap position is a few degrees of magnet rotation past its neutral position.
OTHER QUESTIONS
1. true
2. true
3. false
4. true
5. false
6. false
7. true
8. true
Knowledge Application
1. A magneto has its own source of electrical energy, and it is not dependent upon the battery.
2. The capacitor minimizes arcing at the breaker points, and it speeds up the collapse of the primary current as the breaker points open.
3. A compensated cam is a special cam used in magnetos mounted on high-performance radial engines. The cam has one lobe for each cylinder, and the lobes are ground in such a way that the breaker points open when the pistons in the different cylinders are the same linear distance from top center.
4. These numbers are the sparking order of the magneto, not the firing order of the engine.
5. The primary circuit is connected to ground.
6. Low-tension magnetos are used on aircraft that fly at high altitudes where there is a problem with flashover in the high-tension magneto distributor.
7. The low-tension ignition system has only one coil in the magneto, and it uses a carbon-brush-type distributor. Low voltage is distributed to high-tension transformers that are located on the heads of each cylinder. A high-tension magneto produces high voltage in the magneto coil, and it is sent to the correct spark plug by the built-in high-voltage distributor.
8. A shielded spark plug that has a recess in the shielding in which a resilient grommet on the ignition lead forms a watertight seal.
Multiple Choices
1. b
The magneto magnetic circuit consists of a permanent multi-pole rotating magnet, a soft iron core, and pole shoes.
2. a
A magneto is essentially an AC generator whose output is determined by the speed of the rotor and the strength of the permanent magnet.
To test the strength of the permanent magnet, the magneto is mounted on a test stand and driven at a specified speed.
The breaker points are held open and the primary current is measured with an AC ammeter.
3. b
By definition, the E-gap angle is the number of degrees beyond the neutral position of the rotating magnet at which the breaker contact points open.
It is at this point that the flux change is the greatest and the primary current is the greatest.
4. a
The greatest flux density in the magnetic circuit of a rotating magnet-type magneto occurs when the magnet is in its full-register position.
In the full-register position, the magnet is fully aligned with its pole shoe faces.
5. b
Internal timing of a magneto is the timing of the opening of the breaker points relative to the position of the rotating magnet and the distributor rotor.
Internal timing is best accomplished while assembling the magneto before it is installed on the engine.
6. c
A high-tension ignition cable is “shielded” when it is routed inside a flexible metallic conduit or braid.
The electromagnetic field radiating from the conductor during the time the spark is occurring at the spark plugs, is picked up by this shielding and carried to ground so it cannot cause radio interference.
7. b
If the gap of the breaker points is increased, the spark will occur early (it will be advanced). And, because the magneto will be out of time internally, the spark will also be weak.
8. a
Safety gaps are in the secondary circuit of a magneto to protect the insulation of the secondary coil.
If there is an open in the secondary circuit (such as could be caused by a lead being left off a spark plug), the voltage will build up high enough to cause a spark to jump across the safety gap rather than allowing the voltage to rise high enough to damage the secondary coil insulation.
9. c
When the timing marks are aligned while internally timing a magneto, the magnet is in its E-gap position.
The E-gap position is a few degrees of magnet rotation beyond its neutral position, in the direction of normal magnet rotation.
10. c
The breaker points in a magneto begin to open when the rotating magnet is in its E-gap position.
The E-gap position is a few degrees of magnet rotation past its neutral position.
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