The principle of operation of the limiter of revolutions of the engine and their types: explained in simple words

Here is how it works cut-off speed, and why is it important even for professional racers

The engine needs a Rev limiter to prevent damage to the components of the motor from exceeding the speed of its mechanisms. But what are the different methods that are used for the implementation of the so-called “cut-off” and what can happen if your vehicle doesn’t?

Thus, the “cut-off”, the maximum speed limiter. In accordance with title clear and its purpose is to limit the maximum system speed, which can reach the crankshaft of the engine, thereby preventing increased wear or breakage. Particularly enchanting look “explosions” diesel engines, due to the heavy pistons connecting rods rupture, and they punch right through an engine block, carrying “head” of the motor or of the head of the connecting rod punching the engine block. Plantain are car related injuries are not treated:

The Rev limiter is installed on many cars from the factory, but it is definitely unnecessary to be confused with the red zone of maximum revolutions. Not always, these two indicators coincide. The red zone is part of the engine operating speed, in which to stay the least possible amount of time, with nothing serious on your motor should not happen, except for high fuel consumption and low productivity, but the Rev limiter should stop the set rotation speed beyond the limits of what the engine components can physically withstand.

What types of constraints there are in modern cars?

The Rev limit using the system Valvetrain

One of the examples of business systems technology is a “Valvetrain”. Most of these designs use metal springs to drive the valves and return them to constructively laid the correct position even under hard use. But if the engine spins too fast, the amplitude of the valve springs can go beyond my limits, actually leaving the valve open.

This phenomenon is called “incomplete closure of valves” that is not good. Out of sync at work can lead to loss of compression, misfire, or even the collision of pistons with valves. After excessive “asynchronous” order fresh parts for the engine will be very likely.

The second problem of failure already described above is the breakage of the connecting rod. Alas, if Overspeed, it can happen on gasoline engines, but diesel – it happens more often.

Types of nozzles of the engine for smoothness of operation

There is also the notion of “hard” and “soft” constraints. Hard constraints are those in which you “bump” during an intensive set of speed with a nasty peck when the engine power suddenly disappears. Soft constraints slow down the speed gradually, it’s not so noticeable.

Sometimes, if the vehicle is a soft limiter, the car owner may even ask a question: and it generally is on this engine?

Let’s just say if there is doubt, is there a “cutoff” or not, do not play with fire, you do not need to exceed the rpm in the red zone. Better yet, look in technical documentation, which speed limit declared by the manufacturer for your engine type. Always keep in mind that number is even close to him do not come if you don’t want to go on a sudden THAT on the tow truck.

A “soft” Rev limiter

It can be argued that “soft” limiter is better for road cars because it put less stress on the various components of the transmission and, if to achieve it, it will hold the engine speed at a given maximum, without sudden rebound in a couple of hundred revs down.

On the other hand, a “hard” limiter allows to reach the maximum limit without going over it. One revolution of the crankshaft will not suffice to bridge critical indicator that is the preferred option for race cars.

A “soft” limiter to gradually reduce the fuel supply, slowing and eventually stopping the acceleration of engine.

A “hard” Rev limiter

The “hard” maximum speed limiter cuts off either the spark or the fuel, stopping combustion, and instantly depriving the engine of all its power. This is exactly what creates such a pronounced effect. Combustion in the cylinders will be restored as soon as the revs drop, then, all again.

The third constraint type maximum speed – variable

“Variables”, “adjustable”, “variable” speed limiters are also not uncommon in our day. Usually, they set the maximum speed lower when the vehicle is at idle or when the engine is in warm-up phase. Otherwise, the purpose of them is identical to the previously described variants, not to kill the engine.

Warning!

“Riders” is to commit that if you approach the cutoff, say, in second gear and want to move to third, but instead “stuck” first, even the Rev limiter will not prevent sudden death of the motor. The revs will bounce outside and in this moment with the engine can happen hundred you want! Well, except that, realizing mistake you for a split second turn off the clutch. In General, be careful!

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