What is contact breaker is discussed in this article. The working principle and the types are also discussed. 

What is Contact Breaker

The contact breaker is the mechanism to makes and breaks the primary circuit of the ignition system for obtaining high voltage current in the secondary circuit. It consists of two points named as-

1. Ignition Points.
2. Contact Breaker Points.

In these two points, one point is fixed and the other is moveable. 

 

The moveable point is operated by the rotation of a cam by which the two points come in contact and separate, thus making and breaking the primary circuit. The contact breaker is placed in the distributor housing itself. The cam is fitted to the distributor spindle. 

How do Contact Breaker Points work?

The sequences and the events discussed below, repeat for each cylinder in the engine, firing in the correct order as determined by the engine’s camshaft and distributor. This ensures the engine runs smoothly and efficiently. The working principle of a contact breaker is discussed below-

 

> When the engine is at rest position or about to start, the breaker points are in the closed position.

 

> In this situation, the stationary and movable points are touching, completing an electrical circuit.

 

> After completing the circuit, the current flows from the battery. This current goes to the primary coil of the ignition coil and comes back to the battery again. 

 

> When the camshaft rotates, it pushes the electric cam lobe. 

 

> When the cam lobe moves it opens the contact point. This interruption of the electrical circuit creates a momentary break in the flow of current through the primary coil.

 

> When the point opens, the condenser discharges the stored electrical energy across the points.

 

> The sudden breaking of current in the primary coil induces a high-voltage current in the secondary coil of the ignition coil.

 

> This high-voltage current is then sent to the spark plug via the distributor, which distributes the spark to the appropriate cylinder according to the firing order. 

 

> The spark plug then sparks the fresh charge in the cylinder and this process is continued till we off the engine.

Parts of Contact Breaker

The contact breaker points work on many parts and the main part of this system is the cam lobe. The parts are – 

 

Camshaft

The camshaft is the important and the primary component is the contact breaker system. The camshaft rotates on the base of the engine speed through a belt or the chain. The cam lobes of the camshaft help to open and close the circuit of the contact breaker.

 

Breaker Points

The breaker points are metals made of tungsten, or some durable metal to make contact to pass the electrons in. One of these contacts is stationary and grounded to the engine block, while the other is connected to the low-voltage side of the ignition coil.

 

Condensor

The condenser is connected to the breaker points in a parallel direction. The condensers are responsible for saving the life of the breaker points, by working as a preventing material by absorbing most of the electric current in it. 

 

Ignition Coil

The ignition coil is not a part of the contact breaker, but the whole breaker system is operating on the basis of starting the engine and sending the current to the ignition coil. 

 

Contact Breaker Requirements

The contact breaker is the weaker member of the ignition system. A good contact breaker should have the following requirements- 

 

1. The contact points must open and close at the correct time.
2. They should not produce noise in operation.
3. They should not be oxidized or corroded.

Conclusion

What is contact breaker is discussed above. The main parts of a contact breaker are the cam, contact points, levers, rubbing block(heel), spring, and bush. The contact breakers are made of platinum, tungsten, or an alloy of platinum and iridium.