Since the beginning of the internal combustion engine, the camshaft has been one of the most important components. Automobile engines still operate on the same principle in the twenty-first century.
Camshafts are simple components, lengths of rod or shaft, with some individual cam lobes positioned along them.
The shaft rotates, allowing the shape of the cam to act upon a valve. It’s responsible for pushing against valves that open and close the compression and exhaust strokes. The speed of the rotation controls the rate of its actions.
In this reading, we’ll explore what a crankshaft is, how it works, its diagram, parts, and more.
Let’s begin!
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What is a Camshaft?
A camshaft is a shaft designed to convert rotational motion into reciprocating motion through a series of pointed cams.
Early electric motor speed controllers and mechanically controlled ignition systems, as well as piston engines, which run the intake and exhaust valves, rely on camshafts.
The shaft consists of a cylindrical rod running the length of the cylinder bank. This camshaft works with several cams along its length. Each valve has its own lobe. These lobes force the valve to open by pressing on them.
The valve closure process involves an intermediate mechanism. As the camshaft rotates, there are springs set in place to close the valve. This action happens as the lobes reach their highest point on the push rod, which is when the valve is completely open.
The spring pulls the valve back, causing it to close.
How Does a Camshaft Work?
This camshaft’s working principle is different from modern vehicles. Modern internal combustion engines find camshafts useless in their work. Their calibration controls the amount of air-fuel mixture that enters the chamber.
This air fuel enters at a precise level. After combustion, the exhaust gas exits the chamber, making way for the next mixture.
This design doesn’t just affect the engine’s efficiency and operation. The engine piston’s movement should perfectly synchronize with the valves’ opening and closing. It has a drastic effect on the vehicle’s performance.
A timing belt or chain connects the camshafts, ensuring their timing and turning. It directly moves the pistons inside the cylinder. The working design of the camshaft lobes also controls the speed at which the valves open and close.
This is the working principle of the camshaft in modern engines.
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Diagram Of a Camshaft
Camshaft Material
Metal provides rigidity in the construction of camshafts. We use cast iron because it provides such strength for mass production. Chilled iron camshafts have excellent wear resistance, as the chilling process hardens the material.
Some other elements are added to the iron before casting in order to obtain more suitable properties for its application.
When high-quality and low-volume production is necessary, manufacturers use billet steel. However, it requires more time and costs more than other methods.
Its construction method is either forging, casting, or machining (metal lathe or milling machine). You can use different steel bars.
Major Parts Of The Camshaft
Below are the major parts of a camshaft:
Main Journals
The camshaft’s power comes from a constant rotation. The function of the journals is to keep the camshaft in place as it spins around the engine bay.
Lobes
The lobes rotate in tandem with the piston’s motion as it spins. The functions of the lobes are to open and close the valve for the intake and exhaust gases. The speed of the cam lobes depends on the engine’s speed.
Ends
The design of the cam’s front end incorporates a belt to connect with the crankshaft. The rear end of the cam turns the distributor of the engine with a special gear. This part ensures that the ignition timing is in sync with the rest of the engine.
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Bearings
The main journals mount this component in tandem. It helps prevent the camshaft from damaging the engine block when the engine becomes faulty. Bearings help keep the camshaft’s rotation seamless.
Relationship Of Camshaft and Crankshaft
The two-drive system involves a relationship between the camshaft and the crankshaft rotation. The valve regulates the flow of the air/fuel mixture’s intake and exhaust gases.
For proper opening and closing timing during the piston stroke, the camshaft controls this valve.
This is the reason why the camshaft is connected to the crankshaft directly through a gear mechanism. A timing belt or chain serves as an indirect connection. The direct mechanism process is unusual due to its cost.
Causes Of Camshaft Failure
There are several issues that can arise with the camshaft. Unnoticed issues can lead to the engine’s complete breakdown. Below are the major causes of camshaft failure:
- Lobe wear.
- Improper break-in.
- The oil lifters are equipped with a new cam.
- Mechanical interference occurs as the spring coil binds the retainer to the seals and the valve to the piston. There is interference between the rocker arm slot and the stud.
- Broken cam.
- Excessive end play.
- The dowel pins or keys are broken.
- Incorrect valve spring pressure.