What does a camshaft do?
What is a camshaft ? A camshaft is a rotating object that contains pointed cams, which converts rotational motion to reciprocal motion. It is made of special cast steel in the shape of a shaft or rod and has parts shapes like a cam journal, cam lobe, etc. The camshaft is commonly located in the engine cylinder head.
The number of camshafts on the engine depends on the engine used. If it is SOHC (single overhead cam), then the camshaft on the cylinder head is only one. In contrast, if the engine is DOHC (double overhead cam), then the camshaft is two.
The camshaft has an important function for the engine, whether for an old model engine or a new model engine. The following article will share information about what does the camshaft do on the engine cylinder head. Check out the camshaft function below:
1. To open and close the valve according to the firing order
The first camshaft function opens and closes the valve following the Firing Order (ignition timing sequence). The part that plays a role in closing and opening the valve on this camshaft is the cam lobe.
The cam lobe has an oval shape, where the oval part serves to press the valve so that it opens. In contrast, the round part releases the valve to close the valve due to pressure from the valve spring.
The arrangement and position of the cam lobe on the camshaft is formed based on the Firing Order (ignition timing sequence). As a result, each cylinder's cam lobe protrusion (the oval part) will be in a different position.
2. To rotate the distributor shaft
The next camshaft function is to rotate the distributor shaft. This function is only owned by the camshaft used in engines that use a distributor in the ignition system.
Some add a drive gear to the camshaft to rotate the distributor shaft. Some use a slot model (where the distributor shaft is attached to the camshaft using a slot joint).
The drive gear or the slot model each becomes a liaison between the camshaft and the distributor shaft. When the camshaft rotates, the distributor shaft will rotate.
3. To drive the fuel pump
The other function of the camshaft is to drive the fuel pump. Yes, before using an electric type fuel pump to pump the fuel into the engine carburettor, a mechanical fuel pump is used whose shaft is connected to the camshaft. But, we will find this camshaft function on engines that use a mechanical type fuel pump only.
On the camshaft, there is a special cam that will connect to the fuel pump shaft. The cam will move the fuel pump shaft to pump fuel from the tank to the carburettor when the camshaft rotates.
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4. As a place for the sensor to detect the camshaft rotation angle
The last camshaft function that we know is a place for the camshaft sensor to detect the rotation angle of the camshaft. We can find this camshaft function on the camshaft used in engines with an EFI (Electronic Fuel Injection) system.
The camshafts used in these EFI engines generally have a special construction. It uses a special gear shape or a place to attach the sensor blade to signal the camshaft sensor about the rotation angle camshaft itself. With the special teeth on the camshaft, the sensor can detect the angle of rotation of the camshaft.