The synchronization of the crankshaft and the camshaft is a vital engine principle. But what keeps the crankshaft and camshaft synchronized?
The timing belt, timing chain or the timing gear/idler gear synchronizes the camshaft and the crankshaft.
About five years ago, I cruised my Toyota Camry with my family. Suddenly, my engine voice changed, and I parked the car.
As I opened the hood, I discovered that the timing belt had broken and the crankshaft and camshaft synchronization was off.
Click here to read another article on crankshaft.
Keep reading below for more details.
What Synchronized The Crankshaft And Camshaft Movement
The crankshaft is the source of rotational force in the engine. Therefore, other components, such as the camshaft, gain rotation from the crankshaft.
However, the rotation of the crankshaft and the camshaft must be synchronized. If not, it will cause damage to the engine, including bending of the pushrod or rocker arm damages.
The below components keep the crankshaft and the camshaft synchronized depending on the manufacturer’s design.
1. Timing belt: The timing belt is the element of an internal combustion engine that synchronizes the rotation of the crankshaft and camshaft. Its objective is to allow the closing and opening of engine valves at the appropriate time during each cylinder’s intake and exhaust process. Like other components, the timing belt must be replaced over time and kilometres.
2. Timing chain: It is a classic metallic chain of links synchronized with the movements of the engine crankshaft with the camshafts. This way, the valves open and close without the pistons hitting them.
In some combustion vehicles, the timing chain occupies an essential place. And in other cars, you can find the timing belt instead. In both cases, these parts synchronize the movements and regulate the entry and exit of the different fluids in the cylinders to put the car into operation.
3. Timing gear: The timing gear is a fairly small piece, but despite its size, it fulfils one of the most important functions in the engine of any vehicle, which is to synchronize the crankshaft and camshaft movement.
The timing gear is an invaluable component of an engine.
In most cases, the oil pump is driven outside the transfer case, and the spark timing is always driven outside the transfer case.
That gear is located at the bottom of the distributor shaft and mates with a gear machined into the camshaft.
What Links The Camshaft And The Crankshaft
For the valve and the piston to not hit each other, the camshaft and crankshaft must be linked together precisely.
For such a smooth link between the 2 important engine components, the manufacturer uses one of the following depending on the engine design: timing belt, chain, and timing gear.
The operation of the camshaft depends largely on its type and placement. As we already said, its rotation will activate the valves through a rod or system of rods; no wonder the engine will malfunction or stop working immediately when there is a problem with the link, such as the timing belt.
When my wife’s car has a broken timing chain, the push rod bends due to a broken link between the crankshaft and the camshaft. While fixing the engine, I discovered the valve hit the piston and damaged a piston out of the 4.
What Is The Relationship Between Crankshaft And Camshaft Rotation
There is a cordial relationship between the crankshaft and the camshaft. The connection is like husband and wife; for the family to run smoothly, each of them must play their role.
Similarly, the crankshaft and the camshaft are complementary for the engine to run smoothly.
The crankshaft must go twice for a cycle, while the camshaft must go once.
The crankshaft must complete the four-stroke, which includes intake, compression, power and exhaust.
During these stages, the camshaft must only open the intake and exhaust valve once.
When the piston is making a downward movement, the camshaft must open the intake valve so that air can fill the vacuum in the cylinder.
After the power stroke, the camshaft will also open the exhaust valve so exhaust gases can exit the combustion chamber.
How Can The Motion Of An Engine’s Crankshaft Be Transmitted To The Camshaft
The crankshaft is the source of motion in the engine. The manufacturer uses a timing chain or belt to transfer the motion to the camshaft.
While some manufacturer prefers using the timing gear to transfer the motion from the crankshaft to the camshaft, that is mostly common in the heavy-duty engine where the timing belt and timing chain is considered inappropriate for the motion transfer from the crankshaft to the camshaft.
The motion from the crankshaft to the camshaft must remain consistent as long as the engine runs; if not, some engine components will be damaged.
The crankshaft or crank converts the force of the up and down movement of the pistons into rotational force to move the vehicle.
The pistons are attached to the crankshaft. They create compression in the cylinders when fuel is injected and then ignited.
What Are The Three Ways In Which The Crankshaft Can Drive The Camshaft
In modern engines, there are 3 ways the crankshaft can drive the camshaft. Each manufacturer decided which of the method to use.
1. Timing gear: The function of timing gear is time scale positioning. The time and state of valve action must be consistent with the state and time of piston movement. The crankshaft and camshaft are not on the same axis. A transmission system must connect them.
2. Timing chain: Its main function is to synchronize the movements of the engine crankshaft with that of the camshaft or camshafts so that the valves open and close without being hit by the pistons. The engine would be destroyed if they did (impact each other).
3. Timing belt: The main function of the engine timing belt is to drive the engine’s valve mechanism so that the engine intake and exhaust valves open or close at the right time.
What Is The Ratio Of Crankshaft To Camshaft Rotation
The ratio of crankshaft to camshaft is ratio 1:2. Which means when the crankshaft makes a 2 turn, the camshaft will make a turn.
Mathematically, a crankshaft’s 360-degree movement equals a camshaft’s 180-degree movement. So, when the crankshaft makes a 720-degree movement, the camshaft only makes a 360-degree movement.
The science behind this is the size of the sprocket or pulley of the camshaft and crankshaft.
The crankshaft has a smaller sprocket than the camshaft sprocket, making it possible to make a faster rotation.
If a timing gear links together the crankshaft and the camshaft, then the teeth of the timing gear of the camshaft are much more than the crankshaft.
The size makes the ratio 1:2 between the crankshaft and the camshaft.
What Spins Faster, Camshaft Or Crankshaft
The crankshaft spins faster than the crankshaft.
In a four-stroke engine, the piston reciprocates 2 times, and the crankshaft rotates twice.
During this process, the intake valve opens and closes once. The exhaust valve also opens and completes once. When the camshaft rotates once, the intake valve/exhaust valve opens and closes once.
So, the crankshaft makes 2 turns, and the cam makes 1 turn.
A timing chain (or belt) connects the camshaft and crankshaft. The diameter of the camshaft pulley is designed to be twice the diameter of the crankshaft pulley.
That results in 2 rotations of the crankshaft and 1 rotation of the camshaft. (Just like riding a variable-speed bicycle, the diameter of the front gear is set to 2 times the diameter of the rear wheel gear. When the pedal is depressed for 1 turn, the rear wheel rotates for 2 turns)
Final Thought
The timing belt, timing chain and timing gear synchronize the crankshaft and camshaft.
Remember that the crankshaft runs faster than the camshaft, which makes the ratio 1:2.
There are 3 methods of linking the crankshaft and camshaft together: timing chain, timing belt or timing gear. The motion of the crankshaft is transferred to the camshaft through a timing chain/timing belt or timing gear.
There is a cordial relationship between the camshaft and the crankshaft so the engine can run smoothly. The relationship makes the operation of the valve and piston possible without hitting each other.
Click here to read another article on engine timing.