What is a Camshaft in a Car and What Does It Do?

A camshaft and its various sections

The camshaft in a car engine is a critical component. It opens cylinder valves at appropriate times, ensuring their synchronized operation. Without it, your car would not move. However, its hidden location in the engine makes it a less-understand part. Get to know more about this crucial engine part below.

What is a Camshaft in a Car?

The camshaft in a car engine is the cylindrical shaft rotated by the crankshaft. It has an unmistakable construction consisting of elliptical bulges along its length, set at specific intervals and angles.

Its location varies depending on the engine design or layout. In overhead valve layouts, it sits in the cylinder block (next to the crankshaft). Most modern engines have it in the cylinder head instead.

Parts of a camshaft assembly
Parts of a camshaft assembly
Resource: https://www.vitalmx.com

What are the Basic Parts of a Camshaft

The camshaft is called so for having raised profiles or lobes along its length. It also has other sections, as listed below, alongside their functions.

  • Shaft: the main structure. It holds (and supports) all other parts
  • Driveshaft: the crankshaft connects to it, allowing the transfer of power
  • Cams: the oval profiles that push against various components to open valves
  • Cam followers: the parts that cams operate
  • Bearings: support the shaft and allow it to rotate efficiently by reducing friction

The above camshaft parts receive constant lubrication to reduce wear, especially at the bearings.

Identifying the camshaft in a car engine
Resource: https://youtu.be/GSdvzPavNpE?si=tMNazHXeAMX1jJ1O

What Does a Camshaft Do in a Car Engine?

The camshaft function is to operate engine cylinder valves. It does this by opening them in a timed sequence using raised parts.

As it spins, the raised spots (cams) press against mechanical components that connect to the valve. Each lobe corresponds with a specific valve on the cylinders.

In addition to the timed operation, it determines the period each valve remains open, ensuring the optimal performance of your car. The period the valve remains open, and the amount of lift determines the engine’s power.

Camshaft working
Camshaft working
Resource: https://www.suidkaapforum.com

How Does a Camshaft Work?

The cams are responsible for the process that ends up opening the valve or allowing it to close. They push against lifters, pushrods, rocker arms, and finally, the valve stem. Each lobe has these parts:

  • The nose or highest point that fully opens the valve
  • The ramp that gradually begins to open or close the valve
  • The lowest section, called the base circle, ensures a fully closed valve.

Here’s the camshaft working principle that opens and closes cylinder valves:

  • The crankshaft turns and pushes the piston up. At the same time, the camshaft lobes push the intake valves to open.
  • The air-fuel mixture is now ready for ignition. Meanwhile, the shaft is still rotating, and the lobes no longer exert pressure.
  • The valves close, pulled by the spring. The fuel and air blend burns, releasing energy that thrusts the piston down.
  • The shaft rotation now causes the exhaust lobes to open the valve. The process repeats, ensuring a timed operation of the valves.
Camshaft drive mechanisms
Camshaft drive mechanisms
Resource: https://youtu.be/zdk4fRh9Xxs?si=3S4kg4x_W1MaDTSZ

Types of Camshaft Drive Mechanism

Different engines employ different mechanisms to rotate the camshaft. Depending on their separation distance, the drive is a toothed belt, a metallic chain, or a gear set.

Belt

The belt is typically made of glass fiber and rubber on the back of reinforced canvas. It has one side toothed to provide the required grip. Belts wear quickly but run almost quietly. Additionally, they do not require lubrication.

Chain

The chain rests on sprockets on the cam and crankshaft, with timing marks to ensure its correct installation. Most modern engines use a timing chain. It requires little maintenance and lasts a long time. However, they produce more noise than belts.

Gears

In designs where the shaft is close to the crankshaft, it’s common to use a set of gears instead. The camshaft gear is usually twice the crankshaft gear size. This ratio allows the haft to spin at half the speed of the crankshaft.

Camshaft assemblies
Camshaft assemblies
Resource: https://youtu.be/qqLM23QO31E?si=YiKtCnUGxPepLEKs

Types of Camshafts

Camshafts are classified based on one, their drive shaft shapes, and two, the type of lifters or tappets they employ.

By Shaft Shape

  • Cylindrical – they are cylindrical with grooves for the follower
  • Spherical – they have a spherical design with grooves to guide the follower
  • Radial – radial cams use contour plates to move followers
  • Wedge – these types are pointed on one end with a broad base.
  • Conjugate – they have two rollers connected to the follower for a quieter operation

By Lifter/Tappet Type

A tappet, lifter, or follower is the part that makes direct contact with the raised profiles on the shaft. They are available in two basic constructions: flat and roller.

  • Flat tappet Cam – has a flat bore that the lobes push. Although a less expensive option, the flat type experiences more wear. It also offers a limited lift.
  • Roller Cam – this type uses a roller. It costs more but reduces wear and friction, improving performance and managing a higher lift.

Both designs can be mechanical or hydraulic and self-adjusting. Hydraulic types employ a plunger assembly, while mechanical tappets are solid with no moving components.

What Are Camshafts Made Of?

Camshafts are made from either cast iron or hardened steel. Given their constant motion, they must be sturdy enough to resist wear and damage.

Cast Iron Camshaft

Chilled or ductile cast iron is typically used. Although more expensive, cast iron exhibits superior characteristics, such as resisting wear and damage, making the shafts more reliable over time.

Forged Steel Camshaft

Steel shafts are made from hardened or nitride steel. Nitride steel is a better material, with properties that resemble those of chilled iron casting.

Conclusion

The camshaft in a car engine performs the vital function of operating the intake and exhaust valves. These components are available in many different constructions, so you must select the right type.

If you’re buying camshafts, talk to us at WanTuo. We manufacture camshafts for different vehicles and engines, and our experts will help you navigate their selection process.

Louis
Louis

I'm Louis, a seasoned writer specializing in auto parts, particularly the science behind components like cylinder heads and pistons. With over a decade of experience and a background in mechanical engineering, my articles reflect a commitment to professionalism, blending technical insight with engaging content.

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