What is A Camshaft and How Does it Work?

Before starting with the camshafts, let’s go back to the basics and remember how good old combustion engines work.

An internal combustion engine is a heat engine that converts energy from the heat of burning gasoline. When all is over, the burning gasoline turns into mechanical work, or torque, which applies to the wheels and creates vehicle movement.

Engines have pistons that move up in down inside metal tubes (cylinders). They, in turn, connect with the crankshaft that spins with their help. There may be between two or twelve cylinders with the corresponding number of pistons depending on the vehicle.

All modern engines go through a specific cycle: combustion, intake, compression, and exhaust. Combustion pushes the pistons down from the top of the cylinder. As engines need air to burn fuel, during intake, valves open up and allow ambient air to come in.

When the piston reaches the bottom, the valves close for compression, and it is then sent upward to absorb the intake charge. After that, what remains goes out of the car through the exhaust system.

However, cams play a particular role in that process and closely correlate with the intake and compression stages.

What Is A Camshaft?

A camshaft is a rotating component, a simple rod or shaft, usually made of metal, containing ‘cam lobes’ that convert rotary motion into reciprocating motion.

When the shaft is rotated, the cam allows it to act on a valve or switch to an appropriate degree of its shape, and the speed of rotation controlling the rate of action.

Camshafts are used in internal combustion engines to operate the intake and exhaust valves and in mechanically controlled ignition systems and early electric motors as speed controllers.

Camshafts in automobiles are made from steel or cast iron and are a key factor in determining the RPM range of an engine’s power band.

In a modern internal combustion engine, they are typically, but not necessarily, positioned directly above the cylinder banks where they control the valves.

Their calibration precisely controls the amount of air-fuel mixture entering the chamber and how efficiently the spent exhaust gases from the previous ignition can exit the chamber to make room for the next charge.

Not only does this make them critical to the operation of an engine, but because the opening and closing of the valves must be carefully and perfectly synchronized with the piston movements, they also have a drastic effect on performance.

To ensure this timing, the camshafts are connected to the rotation of the crankshaft via a Timing belt or chain, which moves the pistons in the cylinder directly. In addition, the shape of the cams themselves has been carefully designed to control the speed at which the valves open and close. This is better known as variable valve timing.

The camshaft was described in 1206 by the Arab engineer Al-Jazari. He used it as part of his automata, water raising machines and water clocks like the castle clock.

The first cars to use single overhead cam engines included the Maudslay designed by Alexander Craig and introduced in 1902 and the Marr Auto Car designed by Michigan’s Walter Lorenzo Marr in 1903.

Parts of A Camshaft

Like other car parts, the camshaft comprises various parts, some of which include:

• Cam: This is the most important part of a camshaft. It is responsible for the closing and opening of the valves.
• Cam follower: the part of the camshaft that has been driven.
• Driveshaft: This feature enables movement of the whole camshaft’s structure, and we see it linked with a belt to another engine’s part called the crankshaft or works autonomously.
• Shaft: This is the supporting component of the camshaft, and it binds the other parts together. It can endure stressful workloads while the combustion engine is running.
• Bearings: This part makes sure that the shaft is in its upright position. It is also an important component because it helps reduce friction when the camshaft is in operation. Additionally, it has a special tool for replacing the oil in the camshaft.
• Lobes: This structure provides the camshaft with the opportunity to exchange fuel-filled gases. Also, the lobes’ speed is relative to the engine’s speed.
• Chain sprocket: has a connection to the camshaft at one end. In addition, the chain sprocket along with the timing belt help keep the timing between the camshaft and crankshaft in sync.

How does a camshaft work?

A camshaft is a rod that rotates and slides against a machine to convert rotary motion into linear motion. This change of motion is achieved by the camshaft moving further and closer from from the axis of rotation while the machine pushed the camshaft.

A camshaft on an internal combustion heat engine is a device that controls both the input of fuel and the expulsion of exhaust fumes. It consists of several radial cams, each displacing intake or exhaust valves. This camshaft is connected to the crankshaft via belt, chain, or gears. This ensures consistent timing of the valves in relation to the motion of the pistons.

The camshaft is driven around by a toothed gear, which receives drive through the timing belt or chain from the crankshaft. The four-stroke engine cycle requires two rotations of the crankshaft for a complete cycle, and so the camshaft is driven at half the speed of the crankshaft.

Now, you know the importance of camshaft, but how can we find it working correctly or not? For this purpose, many modern engines come with a camshaft position sensor.

Types Of Camshafts In Car Engines

There are different types of camshafts each categorized based on the following:

• Based on lifters used by the camshafts
• Based on the camshaft’s shape

Based On Lifters Used By The Camshafts

In car engines, there are two major types of camshafts based on the lifters used; they include:

Flat-tappet Camshafts

This camshaft is a very old technology that has been in the automobile industry for years. They are, however, very affordable, produce a high amount of power, and do not wear out over time, which means there is no need for special maintenance.

In addition, this type of camshaft must work with hydraulic lifters or followers. It also makes use of an oil-coated plunger to protect the valves.

In terms of appearance, the flat tappet camshafts look flat at first glance, but with further inspection, their complex geometry becomes noticeable.

Moreover, the face of the hydraulic lifters on the flat tappet has a big circular cross-section. On the other hand, the taper makes sure the lobe is well confined. This makes the tappet run well during rotation.

Roller Camshafts

As the name implies, this type of camshaft uses a roller wheel (cam follower) and a tappet for its operations. It literally only rolls across the lobe of the camshaft. Roller camshafts are more expensive than flat tappets, but they also produce more power and last longer.

In addition, roller camshafts can reduce friction and produce a more curved ramp in the camshaft, which increases the time frame. In contrast to flat-tappet camshafts that require break-in processes, roller camshafts do not need break-in.

When it comes to prices, mechanical camshafts are cheaper than hydraulic roller camshafts, and they also produce quite a bit of power, which makes the industry consider them a standard power generator. But its disadvantage is that it requires constant maintenance.

Based On the Camshaft’s Shape

• Cylindrical Camshafts. From its name, it is cylindrical in shape, and it is also known as a barrel or drum cam. Its surface has a groove cut into it, which the cam follower makes use of for motion.
• Radical Camshafts. This can also be known as a “disc clam.” It has an axis that is directly normal to the follower’s movement path. Also, radical Camshafts possess a shapeless contour plate that transforms the motion of the cam into that of the cam follower.
• Conjugate Camshafts. A conjugate camshaft comprises two rollers that connect the cam follower or driver together. These rollers restrict the motion of other parts, which results in the elimination of noise for quiet machine processes. They are most suitable in areas that require the silent operation of the camshaft.
• Spherical Camshafts. They are spherical in shape. A groove is located on the curved design. In this type of camshaft, the speed of the cam follower is perpendicular to the rotational part of the spherical cam.
• Wedge camshafts. Their endpoints are very sharp, along with a wide basement. However, in wedge cams, the driver moves in a sliding manner in relation to the camshaft.

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