A distributor is an electrical and mechanical device that every older spark-ignition engine had in the ignition system. The distributor is routed from the ignition coil to each spark plug at the right time.
What is an Ignition Distributor?
A distributor is a device that rotates an enclosed rotating device that is used in I.C. engines with mechanically timed ignition.
A company, namely Delco, invented the first battery-powered ignition system that was reliable. Later, it was developed by Charles Kettering and was a wonder at the time.
In the magneto system and most computer-controlled engines, the distributor has a mechanical or inductive breaker switch to make and break the primary circuit of the ignition coil.
The main function of the car distributor is to send the high voltage current produced by the secondary coil to the proper spark plugs in the proper firing order and at the right time. Now, let’s look at the parts of a distributor.
Parts of the Distributor
The following are the parts of a distributor:
- Cam
- Capacitor
- Condenser
- Contact breaker
- Distributor cap
- Terminals
- Distributor shaft
- Drive Gear
- Rotor
- Spark advance mechanism
#1. Cam.
The cam is part of the distributor, fastened to the distributor shaft, and rotating with it. It has lobes to open the contact breaker point.
If there are four cylinders in the engine, for example, there are four lobes in the distributor. When the cam turns, it drives the cam, follower, and the breaker points are parted and the current is broken.
#2. Capacitor.
It also has a capacitor to protect the contact point of the contact breaker from burning out, also improves the output of high voltage current by reversing the direction of the high-tension current flowing through the primary coil.
#3. Condenser.
Each ignition distributor is provided with a condenser at the contact points to reduce the sparks as contact is broken, and in this way reduces burns and pitting of the points.
The arcing is due to the effect of self-induction in the coil as the points break contact and thereby close off the flow of current.
#4. Contact Breaker.
The contact breaker is simply a mechanically designed breaker point. One part of the breaker is fixed while the other section moves. It makes and breaks the primary circuit current. It is connected to the breaker assembly.
When the cam’s lobe forces the cam follower of the contact breaker, they break contact with each other and break the primary current to the ignition through the primary winding of the coil.
#5. Distributor Cap.
It is easy to guess what this cover is. It protects the internal parts of the distributor system as well as ensuring the contact between the internal rotor and the spark plug wires.
There is only one post for each cylinder, and with contact point type ignition systems, there is a central post connected with the ignition coil so that they can draw off current from it.
#6. Terminals.
There is a terminal inside the distributor cap corresponding to each post. The plug terminals are arranged around the periphery of the cap in the firing order so that the secondary voltage goes to the correct spark plug at the right time.
#7. Distributor Shaft.
The distributor shaft is located inside the ignition distributor. This shaft is driven from the camshaft of the engine by a gear drive. It carries a cam that is utilized for breaking the contact of the contact breaker.
#8. Drive Gear.
The distributor gear is so proportioned that the distributor will make one complete turn for each complete turn of the crankshaft, and for every two complete turns of the camshaft.
This provides for the burning of the spark plugs in the proper position of the piston. The drive gear is secured to the distributor shaft by means of a steel roll pin.
#9. Rotor.
The distributor rotor is a device in a spark ignition system that carries a spark generated by the ignition coil and brings it into proper contact inside the distributor cap. It is driven by the camshaft of the engine and is therefore properly timed with it.
As the camshaft revolves, the distributor shaft is also rotated, which causes the rotor fastened to the distributor shaft to likewise turn.
#10. Spark Advance Mechanism.
It is a mechanism used to drive the spark in spark-ignition engines. It is necessary to burn the fuel before the piston reaches TDC. This enables the air-fuel mixture in the cylinder to burn completely, giving therefore the maximum pressure on the piston.
There are usually two kinds of spark advance mechanisms in this, i.e., centrifugal advance spark mechanism, vacuum spark advance mechanism.
Function of Ignition Distributor
The working of the ignition distributor is quite simple. When the distributor shaft began to rotate, it also rotates the cam and rotor of the distributor. As the cam rotates it pushes the cam follower that is connected to the contact breaker.
The contact points of the contact breaker suddenly open and close the primary current through the primary winding, and accordingly cause the high voltage current to flow in the secondary winding.
This high voltage current passes to the central terminal of the current distributor. This, in turn, passes through the carbon brush onto the outer edges of the rotor.
Finally, as the rotor comes into contact with the internal terminal of the spark plug in the distributor cap, a high-voltage electric pulse passes into the spark plug and gives a spark within the cylinder head.
In this way, the distributor generates a spark in each spark plug in order and at the right time.
Distributor Problems
A running engine gives a high power to the rotor through the ignition coil that rotates inside the distributor rotor. The rotor, in turn, sends energy through the spark plug wires of the engine cylinders in a generally correct firing order.
The rotor and cap keep the contents of the distributor away from the engine and keep the parts of the distributor clean and neat, as they bear an incredibly high voltage of energy and put it into the proper spark plugs.
The spark plug takes a spark from the distributor and uses it to ignite the fuel mixture in order to keep the engine running.
While the vehicle is running, there is a high voltage present throughout the entire distributor system. But if there is a problem with it, there will not be voltage going to the proper spark plugs to keep the engine running.
Right away, the rotor and cap of the distributor, when worn out, will show certain symptoms that will warn the driver of service that may be urgent. Let us look into the symptoms caused by the bad distributor.
- Engine misfiring
- The car does not start
- Abnormal Shaking
- Excessive or unusual engine noises
#1. Engine Misfiring.
Engine misfiring will probably occur occasionally for a variety of reasons. However, the safest place to service your distributor rotor and cap is to determine if they need replacing.
It also guarantees that the distributor rotor and cap are in their most optimal condition.
#2. Car Does Not Start.
If the distributor cap is loose or out of order, the engine cannot transfer a spark through the full circuit necessary to move the cylinders and move the car. Correcting it keeps the car running.
#3. Abnormal Shaking.
This is the commonest symptom that will begin with a small vibration and culminate in shaking that can be felt throughout the whole vehicle.
This shaking might be the result of the distributor cap and rotor not performing correctly, affecting the timing and firing process.
#4. Excessive or Strange Engine Noises.
Your vehicle will make some very weird sounds if the distributor rotor and cap are faulty – especially because the cylinders will seek to fire, but can’t.
When the distributor rotor and cap are failing, you may notice a noise like a tapping, clicking, or sputtering sound.
Wrapping It Up
As I have said above, the distributor is a rotating shaft of spark-ignition engines that serves to supply the voltage or current from the ignition coil to the spark plug in the proper firing sequence and time.