Engine braking is one of the tricks available to the driver, which are aimed at reducing the speed of the vehicle without the use of the brake system. There are different opinions among motorists about this method. Some argue, that braking by the diesel or petrol engine allows to save petrol or diesel fuel, the braking process itself reduces the risks compared to using the brakes in certain situations.
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Opponents of this method among the main arguments are increased engine wear and reduced transmission life due to abuse of engine braking. Next we will consider, how to brake the engine, when it is necessary to do it and how to carry out the specified braking by the engine correctly?
Why the car slows down when braking the engine
This method of braking involves a certain resistance of the motor to inertial load, which tries to increase the speed of the crankshaft. In other words, the engine starts to brake the car at that moment, when the machine is moving at a certain speed with the transmission engaged, but at this time the fuel supply is stopped or minimized.
Cessation of fuel means, that the engine no longer gives energy to the transmission. It turns out, the transmission begins to transfer load to the motor from rotating wheels by inertia, the crankshaft speed decreases and the car loses speed, that is, brakes the engine.
Next you need to consider those features, due to which braking is carried out. It is worth starting with that, that a noticeable slowdown of the car when braking the engine may not always be. Depressing the accelerator pedal increases the fuel supply, resulting in increased crankshaft speed (the motor spins). The pedal is released means, that revs are falling.
Not going into much detail in the design of the transmission, that the task of the gearbox is to distribute torque to the wheels. In other words, The checkpoint "doses" energy, which gives the engine, depending on the selected transmission.
Riding on low (1-2-3 broadcast) provides return of the maximum energy on wheels, but the car will not accelerate to high speeds. Include increased gear (4-5-6) will allow the car to go faster, but the intensity of acceleration decreases, as the box will not allow to transfer so much energy to wheels, how much was transmitted at reduced speeds.
Increased gears (5-6) accelerate the car much weaker, often allowing only to maintain the previously gained speed of the car. When driving in high gear there are significant forces of inertia, as a result resistance of the internal combustion engine and the check point is specially reduced by designers to a minimum.
It turns out, dynamic acceleration is possible only at low speeds. If you release the gas at this time, then the resistance to inertial motion will be great. If you stop pushing the accelerator in high gears, the machine will not slow down intensely, since the resistance is low.
Advantages and disadvantages of this method of braking
The main advantage of this method of slowing down the MS is a significant reduction in the risk of skidding when braking the engine. The point is, that when braking by means of regular brake system there is a blocking of wheels, which makes the car unmanageable. On machines with active electronic safety systems, this effect is minimized, but even the presence of ABS does not preclude skidding, especially on slippery surfaces.
For this reason, engine braking is on the list of emergency measures, allowing you to slow down on slippery or wet roads. This method of braking is actively used when driving on a long descent, as well as when moving on mountain roads and serpentines. In the first case, locking the wheels is excluded, and in the second the risk of overheating of brakes as a result of too active use decreases.
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Some drivers also brake the engine in the case, if the road situation allows to roll on the included transfer, thereby saving fuel, extending the service life of brake pads and tires. Many are attracted to this aspect, that the fuel supply when the accelerator pedal is released on modern injector cars, which are equipped with a manual transmission, completely stops.
Additionally, you should consider the possibility of engine braking in that case, if the brakes are completely or partially out of order. It should be reminded, that it will not be possible to stop the car at once, especially on the descent. The speed can be significantly reduced to relatively safe, then it becomes possible to stop or apply contact braking with minimal risk and / or damage.
In the list of the main shortcomings of braking by the engine note that, that the brake lights on your car are not lit at this time, as the driver presses the brake pedal. Car driver, following you, may just not notice the slowdown, which will lead to an accident or emergency.
How to properly brake the engine: "Mechanics" and "automatic"
In the arsenal of specialists there are about two dozen techniques for braking the engine. In practice, it will be enough to learn the basics. Be sure to read all the recommendations to the end!
Braking by the engine and a mechanical box at rather high speed should be carried out as follows:
- the accelerator pedal must be released;
- the clutch pedal is depressed;
- then the reduced transmission is included (most often 3);
- after deceleration turns on 2 broadcast;
- when the speed decreases, can be included 1 transmission;
Even if you are moving on 5 or 6 transmission, it is desirable to include the third, since the slowdown on 4 and higher gears will be weaker. We will note separately, that this instruction is general. In a particular situation, it is necessary to take into account the initial speed and choose the right moments, when to make the first "down" switch and the next.
If you abruptly engage too "low" gear then, when the crankshaft speed is high, then the braking force may be too significant. In this case, the wheels are temporarily locked, the car can bring and so on. d. As for the engine and transmission, then such a load can lead to the breakdown of certain components and subsequent repairs. For a more gentle switch "down" in a quiet environment, it is better to refuel.
Refueling should be understood as squeezing the clutch and disengaging the transmission with the transfer of the box to "neutral". Then you need to press the accelerator pedal, thereby raising the engine speed, after which the clutch is pressed again and the reduced transmission is engaged. In an emergency, you can simply squeeze the clutch, press the gas and immediately turn on the reduced.
Always remember, which is strictly forbidden in any situation to try to include after 4-5 or even the third immediately first gear! As for working with the clutch pedal, then release the pedal after engaging the downshift very gently and smoothly. You can not abruptly throw the clutch! It is necessary to slightly delay the clutch pedal at that moment, when the start of the engine-transmission connection is felt.
On cars with an automatic transmission, the possibility of engine braking will depend on the type and design features of the transmission. Also from the type of automatic transmission and from those opportunities, which are available to the driver, will directly depend on the general algorithm of actions for braking by the engine with a box "automatic machine".
There are boxes, which allow you to implement sequential gear changes in manual mode. Another type provides only fixed modes with the ability to select reduced gears. There are also automatic transmissions, which are not designed for any interaction with the driver. Carefully read the instructions for your car for comprehensive information on automatic braking., contact the official representative of the brand, visit the profile forum on the Internet, etc.. P.
Let's summarize
Quite obviously, that mastering this braking technique will be the right decision for every driver, especially if the car is on "mechanics". This should always be taken into account:
- Only competent execution means, that you will not damage the gearbox and motor. It is not necessary to abuse this way or to brake sharply the engine unnecessarily.
- This method of braking can create an emergency situation on the road for vehicles moving behind you, improper performance reduces the life of the engine and transmission, and can lead to serious damage.
- As for fuel economy, then the benefit of this method of braking is extremely small.
- If the car has an automatic transmission, then it is necessary to study separately and with increased attention the question of the possibility of implementation and the general feasibility of braking the engine on a particular model of car.