First of all, let's say that the gears of any transmission are designed to regulate the speed of torque transmission from the engine to the drive wheels. They are divided into straight lines, as well as increasing torque and reducing it. Here we will discuss the latter in more detail.
and its purpose
Simply put, a downshift is the one that is in the transfer case, or otherwise, an additional box that distributes torque between the two drive axles. When it is turned on, the speed of the car drops, and the torque and power increase. This gear is often used when overcoming obstacles such as ice, fords, steep descents or ascents, sand, mud, rocky roads and heavy off-road conditions.
It is activated by a button or a lever with the designation L and LO, which means short for low - "low". The principle of downshifting is that when it is turned on, the speed of the SUV drops, but at the same time it becomes stronger and more capable of overcoming obstacles. The amount of speed drop depends on the gear ratio in the gears. The car moves at high speeds when downshifting.
For example, consider a situation where the motor does not have enough power during a long climb in third gear, and when the second gear is engaged, the number of revolutions becomes too high. In this case, the inclusion of a lower gear helps to cope with the situation: the car is moving at low speed, but at the same time at high speeds. Thanks to the increase in torque on the wheels, overcoming obstacles on the road becomes much easier. The number of revolutions of the bridge increases with secondary shaft. Due to this, the car can more easily overcome strong impassability, water obstacles, descents and ascents and other obstacles.
Demultiplier
The demultiplier is structurally included in the transfer case circuit or is made as a separate unit. In the "machines" the transfer case may not be present, and its functions are performed by some parts and assemblies in the gearbox. An additional gearbox, in which there is a reduction gear (demultiplier), is designed to increase traction on the wheels. The demultiplier is a transmission mechanism that is designed to increase torque. It is installed, as a rule, on those cars that are intended for operation in bad road conditions. IN this case the usual number of gears in the box will not be enough, getting an intermediate gear ratio in the transmission will help here.
Consider the following situation: in fourth gear at a certain speed, the motor operates in specific conditions with an overload, in lower gear, third, the engine is “twisted”. In this case, an additional gearbox will help.
How to turn on the downshift?
It is necessary to stop the car, after that the main gearbox lever is moved to the neutral position, and the lever additional box- in the "downshift" position. Then we squeeze the clutch. Not all transmissions have a separate transfer case. In this case, a conventional gearbox has a special lever with which this gear is engaged. If the downshift is switched on in the normal mode, then in this case there is a high risk of overloading both the engine and the transmission. As a result, both units can fail.
Application of underdrive and differential lock
So, as we already understood, lowering - additional gear, which reduces the number of revolutions of the wheels at constant engine speeds. It is usually set to transfer case. Having it makes an SUV more expensive, heavier and more difficult. But it is not always installed on economy class cars; instead, connecting the power take-off shaft to the gearbox rear axle takes place in the gearbox, in the underdrive housing. Last time frame SUVs is getting smaller, and crossovers are moving closer to city cars. These cars often lose downshifts as well. Now there has been such a trend that the priority is the presence comfortable conditions in the car than off-road qualities. Most manufacturers are moving to and frame construction remains a thing of the past. True jeeps are still those SUVs that have a reduction gear and differential lock, so they are not afraid of any obstacles.
Differential lock is necessary to improve patency. The differential itself is divided into interwheel and interaxle. Formerly cars did not have such technologies, so their absence had a negative impact on the safety of the elements in the design. The cross-axle differential allows the wheels to rotate with different speed, this is necessary, for example, if the car makes a turn. But its presence can lead to the fact that when slipping, the power of the motor will go only to the wheel that is stuck, while the other will be motionless. When the differential is locked, the engine energy will be distributed between the wheels already equally, and thus the car will be able to overcome the obstacle.
It is similar in its principle of action: it allows the front and rear axle move at different speeds and on different paths. But in some situations, this can significantly complicate management: if the front wheels are stuck, the rear ones will be inactive. blocking center differential can successfully solve this problem. SUVs, known for their excellent cross-country ability, are usually equipped with three locks: rear, front and center differential.
SUVs with low gear and differential lock
At present, there are still real off-road conquerors equipped with everything necessary equipment, in order to feel as comfortable as possible on any surfaces. These vehicles include, for example, Chevrolet Trailblazer, Hummer H3, Land Rover Discovery.
"Trailblazer" has a large body, frame structure and just a huge list technical advantages. He has a bright and brutal appearance. In 2015, the model received quite significant updates both in the exterior and in the technical "stuffing". The suspension is soft, but this fact introduces some drawback to the control of the SUV: a slight roll appears during sharp turns. The car pleases with the quality of the trip that it can provide if available. complete set necessary systems.
Now let's move on to American model a real conqueror of off-road - "Hammer". At the heart of the production of this car, the concern used to a greater extent military technology. It is not surprising that he was able to create a real brutal SUV. Mass production it was stopped back in 2010, and last year it was announced that the Hummer H3 can only be purchased at special order. The car has a huge ground clearance, big engines, magnificent wheels shod in off-road tires, and, importantly, it is equipped with one of the best systems low gears and differential lock, which are borrowed from the military industry.
"Discovery" remains one of the few British SUVs that have retained the frame structure. It is distinguished not only by excellent external data, but also increased comfort, as well as permeability. The range of engines, although not distinguished by a rich choice, looks impressive. Locking is available on it in several modes, and the car also boasts a good all-wheel drive. The reliability and quality of the car is truly impressive.
Such jeeps can be successfully operated in urban conditions, but still their true purpose as large and heavy vehicles is real off-road. It should be noted that such cars cannot be called economical, and they are also equipped with big list functions that are not useful for using a jeep on paved roads.
Types of reduction gears
Worm gears are used as reduction gears, less often cylindrical and planetary gears. The worm gear is one of the gears with intersecting shaft shafts. The movement in them is carried out on the principle of a screw pair. Its main properties are low level noise due to gearing features, relatively low efficiency, small dimensions and large gear ratio. Compared to a worm gear, it provides better running smoothness. This type of transmission has a much greater potential for increasing torque and reducing speed than gearboxes with other types of gears. Cylindrical gears are used in mechanisms with parallel shafts. For this type, increased accuracy is required due to design features.
Gear drives are reliable and durable, subject to acceptable level loads, one of the minuses can be called the moment that when high speed rotation such a mechanism has high level noise, and also cannot respond flexibly to changing loads. A variety of gears are planetary. They have movable axles. Such transmissions are light in weight, easy to assemble, compared to conventional ones. gears produce less noise, as well as the possibility of obtaining greater gear ratios. Among the shortcomings can be called a large number of parts, increased requirements for the accuracy of installation and manufacturing.
Manual transmission is popular among drivers. Of course, the production of new cars equipped with manual transmission is declining every year, but nevertheless experienced drivers stay true to mechanics.
Without a doubt, it is one of the most proven and reliable. She is competent and proper care can be used for a considerable period of time.
At first sight inexperienced driver it may seem that it is inconvenient to use and inferior in comfort to automatic and robotic devices. This common misconception has arisen because many drivers do not know how to properly shift gears on the mechanics.
The manual transmission is used to distribute the mechanical energy of the motor over the drive axles vehicle. Cars use manual box gears with different number of steps. The most popular are 5-speed transmissions and reves.
A manual gearbox uses a clutch to shift gears. It is the link between the engine and transmission. Crankshaft the motor is constantly rotating. input shaft box is engaged with the crankshaft.
In order to connect the desired gears of the gear speed, it is necessary to suspend the rotation for a split second crankshaft. The clutch handles this well. That is why it is impossible to change gear without the clutch depressed.
How to change gears on the mechanics
An experienced driver shifts gears on the mechanics automatically, without controlling the course of the hand. All movements are reflex in nature and their clarity is due to driving experience.
We can distinguish the following order of gear shifting on a manual transmission when starting to move:
- Depress the clutch and place the gear lever in neutral position;
- Start the engine while holding the brake pedal;
- Release the brake pedal and press clutch pedal;
- Without releasing the clutch pedal, engage first gear;
- Slowly release the clutch and move off;
- If necessary, add speed with the gas pedal;
Once you start moving, you don't need to change gears too often. Typically in urban dense stream vehicles use third gear. When accelerating the vehicle, it is necessary to shift gears strictly in ascending order.
If necessary apply emergency braking depress the brake and clutch pedal at the same time. The gearshift lever can be moved to the neutral position later.
The following gear shift ranges in mechanics can be distinguished:
- first gear (0-20 kilometers per hour);
- second gear (20-40 kilometers per hour);
- third gear (40-60 kilometers per hour);
- fourth gear (60-90 kilometers per hour);
- fifth gear (90-110 kilometers per hour);
- sixth gear (over 110 kilometers per hour).
As practice shows, experienced drivers determine the necessary moment of gear shifting by the sound of the engine. strained roar power unit indicates that it is time to change gear.
Do not forget that timely gear shifting prevents premature engine wear, reduces fuel consumption and reduces emissions. harmful substances V environment. It must be remembered that the clutch is squeezed out smoothly and the gears change quickly.
Gear shifting manual transmission when overtaking
Minimum fuel consumption and optimal speed engine are achieved when the car is moving in high gear on a country road. Many drivers, and especially beginners, make a series of common mistakes with other road users.
Most beginners, when overtaking a vehicle, include a high gear and thereby lose dynamics and speed. Experts, on the contrary, recommend lowering the transmission speed by one step at the beginning of overtaking.
This will add agility to the engine and the speed of the vehicle will instantly increase. Thus, dangerous maneuver will be completed successfully. No need to tempt fate and shift gears while overtaking.
How to brake properly
There are situations when it becomes necessary to use the engine and gearbox for effective braking. Reducing the speed of the vehicle by using the capabilities of the engine is used when steep descents, failure brake system, malfunctions of the brake system and slippery road surfaces.
Engine braking actions are as follows:
- Release the gas pedal;
- Squeeze the clutch and shift into low gear;
- Slowly take your foot off the clutch pedal.
When braking the engine, care must be taken, as incorrect operation can lead to damage. mechanical box gears.
Conclusion
In principle, shifting gears correctly on the mechanics is not as difficult as one might imagine at first glance. The most important thing is to fast with patience, and experience and skills will come with time.
Thank you for your attention, good luck on the road. Read, comment and ask questions. Subscribe to fresh and interesting articles of the site.
The art of driving a car requires many years of practice. We begin to train how to drive a car correctly in driving school. However, even after graduation, many do not know all the intricacies of driving a car. It is not enough just to pull the gear lever in the right direction - you also need to be able to properly up and down gears. At proper management the car will move smoothly, and passengers will appreciate the talent of the driver.
Motorists who are interested in the question of how to downshift correctly, first of all, need to know that you need to switch the box only when the car speed has dropped to the desired level. For the first gear, a speed of 0 to 20 km/h is required, the second - from 20 to 40 km/h, the third - from 40 to 60 km/h, the fourth - from 60 to 80 km/h, the fifth - from 80 km/h and higher. If these ratios are not observed, the car will twitch sharply, which leads to rapid wear details.
Drivers who know how to drive automatic transmission gears, it will be quite difficult to change to mechanics. Operating a manual transmission requires some experience and skill. Downshifts must be done in a certain order. When decelerating, an experienced motorist always shifts the gearbox to neutral first, and only then engages the desired gear depending on the speed of the car. On a slope, to save gasoline, you can drive the car all the time with the gearbox in neutral. However, do not abuse this style of driving. If the slope is too steep, it will be very difficult to brake in time
By the principle of operation, gears are lowered in the same way as they are increased and how the reverse gear is engaged. First, the aiming pedal is pressed all the way down, and then it turns on desired gear. After that, add gas and slowly release the clutch pedal. When downshifting, do not look at the box so as not to be distracted from the road. Gear shifting should be automatic. This habit is developed through practice.
5. Special attention should be paid to the discussion of the issue of emergency downshifts when hard braking in front of a pit, for example. Before shifting gears on the mechanics, you should sharply apply the brake and only after that turn on the lower gear, usually the first one. Then, in low gear, smoothly drive through the pit. Knowing all the subtleties of driving at low speeds, you can show a real master class on the road. The skill of the driver is not in the speed of driving, but in the ability to shift gears correctly, and therefore smoothly drive the car.
Despite the ever-increasing popularity of cars with automatic transmissions, mechanics remain the favorite of many drivers. Driving a machine with a manual transmission - it is the basis of driver skill.
Therefore, even if you plan to purchase a car with an automatic or CVT, the mechanics control skills will not be superfluous. Mastering this science is not as difficult as it seems.
How to change gears on the mechanics?
When driving a car with mechanics, the driver switches gears on his own. Gearboxes are usually 4 or 5 speed as well reverse speed . While driving, the driver should not look at the gearbox when changing gears, his actions should be automatic.
Therefore, it will be useful to study the location of the speeds with the engine turned off.
Gear shifting is carried out simultaneously with pressing the clutch pedal. The pedal must be fully depressed.
Particular attention should be paid to the technique of pressing the clutch pedal. : all actions should be smooth and synchronous. If the clutch pedal is abruptly released, the car may stall or start to twitch.
To start driving a manual car, follow these steps:
- start the engine while keeping your foot on the brake pedal. The gearbox must be in neutral
- turn on first gear while depressing the clutch pedal
- release the clutch pedal smoothly without jerking, pressing the gas at the same time
- keep accelerating with the gas pedal fully releasing the clutch.
Remember that if you need to go uphill, it is better to do it with parking brake. Release the lever just before driving. This will prevent the vehicle from rolling back.
It is necessary to change gears smoothly, without sudden movements.
The faster the speed of movement increases, the more actively you need to switch to more high gears. When you achieve perfection in this technique and achieve a smooth ride when driving, the moment of gear change will become completely invisible to your passengers.
Upshifts must be sequential.
Jumping over the gear is not prohibited, however, the abuse of such a maneuver can lead to transmission malfunctions. If you slow down, then you can select the necessary gear based on the conditions and intensity of speed reduction.
Jumping through the transmission in this case will not adversely affect the operation of the engine.
Gear shifting on the go
An experienced driver will not think about switching gears. It takes a little practice to get this automatic.
In order to change gear in time, focus on the speed of the car and the number of revolutions.
For each car, the optimal moment for changing gears is individual and depends on the transmission settings, vehicle power and other technical characteristics.
The general guideline for switching speed is the moment the engine reaches RPM with a value of 3000 - 4000.
Concerning speed limit. What are the following approximate guidelines?
- from 0 to 20 km/h- first gear;
- from 20 to 40 km/h- second;
- from 40 to 60 km/h- third;
- from 60 to 90 km/h- fourth;
- over 90 km/h- fifth gear.
To change gear while the car is moving, you must:
- squeeze the clutch while releasing the gas pedal
- with the clutch fully depressed, shift the gearshift lever gear to the right position
- gently release the clutch while continuing to accelerate the vehicle with the gas pedal.
Overtaking shifts
When driving on the highway, the driver usually selects a gear that allows you to maintain optimal speed driving with minimum fuel consumption. Usually it is fifth or fourth gear.
If it becomes necessary to overtake, first of all, you need to make sure that the maneuver is safe and that there are no prohibition signs.
The sequence of actions during overtaking is as follows:
- you need to get closer to the car in front, and equalize the speed of movement, while maintaining, of course, a safe distance;
- make sure that Opposite Lane free;
- shift into a lower gear. For example, if you were in fifth gear, shift into fourth;
- overtake quickly and accurately.
A common mistake when overtaking is trying to do it without shifting to a more dynamic gear.
In this case, when an oncoming car appears or an increase in the speed of a passing car, it will be very difficult to pick up speed sharply. Overtaking in this way is possible only if the oncoming lane is free at a sufficiently impressive distance.
Gear shifting under engine braking
Many experienced drivers practice the correct implementation of vehicle braking using a downshift, which is called differently: "downshifting".
This skill can come in handy in the cold season to prevent the car from skidding when braking in icy conditions.
In this case, you need to take your foot off the gas pedal, wait for a slight decrease in engine speed, depress the clutch pedal and switch to a lower gear. Then gradually release the clutch and continue driving at a lower speed.
The main difficulty with such a maneuver is to identify the moment of gear shifting. This is especially difficult in extreme situations.
parking
When parking a car, you must act as accurately and carefully as possible.
It is necessary to check in at the selected place in the lowest gear with your foot on the clutch pedal, so that in the event of a dangerous approach to an obstacle or another car, you have time to slow down.
IN emergency You can apply the brake abruptly without first depressing the clutch pedal. This will cause the car to stall, but it will help to stop it abruptly.
After the car has come to a complete stop, turn off the engine and engage first gear by depressing the clutch. This will prevent the machine from rolling.
It will not be superfluous to raise the parking brake lever. Many drivers, when parking on slopes, to ensure more security turn the wheels in the direction opposite to the angle of inclination.
Introduction to the gearbox
In order to quickly master the control of a manual transmission, it will be useful to understand its internal structure.
Certainly, to know everything technical subtleties not necessary but understanding general principles her work will be very helpful.
The vehicle is moving by transferring the rotation of the motor shaft to the axles of the wheels. This transmission is precisely carried out by the mechanical transmission gear system. For different cars, the diameter of the transmission gears is different, the number of teeth and the gear ratio may be different.
The car can move at different speeds the same job motor shaft.
Thus The gearbox regulates the engine's operating mode depending on the number of revolutions and speed.
Since the transmission shaft is in constant motion, a clutch is needed to change gear. Depressing the clutch pedal causes the gears to disengage, which then start working in the new position.
A serviceable gearbox should shift gears easily with minimal effort, without difficulty or extraneous sounds.
The advantage of mechanics is also lower fuel consumption compared to automatic. Manual transmission correct operation more secure in winter time of the year.
Newbie mistakes when working with a manual transmission
The main difficulty for novice drivers is achieving automatism and synchronism when shifting gears and pressing the clutch pedal. Even the quickest glance at the box or under your feet can provoke an emergency.
Therefore, it is necessary to improve your mechanical control skills at specially designed circuits.
A common mistake is hard release of the clutch. The machine may stall at the same time, and the systematic repetition of such an error may lead to premature wear engine.
Another rookie mistake is not knowing when to shift gears. In order not to be mistaken, be guided by the readings of the tachometer and speedometer, and also listen to the sound of the engine.
Do not abuse the clutch pedal unnecessarily, as this can lead to clutch wear. So, at the traffic lights it is better to turn on the neutral gear.
Be careful when using reverse gear. Remember that it cannot be turned on until the car has completely stopped. Be careful when driving in reverse. With a sharp press on the gas pedal, you can accelerate very quickly.
It is also necessary to get rid of the fear of driving, not forgetting, of course, about reasonable caution..
If you don't feel confident enough, practice at designated driving training areas or in the city during off-peak hours.
Control of the correct movement on the tachometer
Tachometer- This is a meter that shows the number of revolutions of the engine. It is necessary to take into account the readings of the tachometer when shifting gears. The optimal value for changing speed is 3000 rpm. However, on different cars it may differ.
Do not allow the tachometer needle to reach the red line , which represents the most high rate engine speed. Also make sure that the arrow of the device drops too low. In this case, you must shift to a lower gear.
Given these simple rules and mastering the art of operating a manual transmission, you can experience the pleasure of driving a car, feel its dynamics and power.
In dense city traffic mechanical transmission may cause some discomfort, but this disadvantage is compensated by the possibility of complete control over the dynamics of the car, reliability, economy and cheaper after-sales service compared to an automatic.
Do you want the car to buck? Turn on low!
Downshifting is a little more difficult than upshifting. If you are a novice driver and this is not obvious to you, do the following: accelerate to 50 km / h in third gear, shift into second gear and quickly release the clutch pedal as usual. As a result, the tachometer needle will jump up sharply, and the car will twitch great. Try it! Happened?
This will always be the case when moving from overdrive to reduced, only the intensity of the jerk will be different depending on the speed and gear. Why is there a breakthrough? As the sharply “bouncing” tachometer needle shows us, when the gear is lowered, the engine speed increases. If when switching from II to 3rd gear the arrow drops from 3500 to 2500 rpm, then when switching from III to II, on the contrary, it jumps from 2500 to 3500. This means that, including a lower gear, we forcibly accelerate the engine to more high speed. Since the rotating parts of the engine are heavy, inert, they resist spin-up, which is expressed in the jerk of the car. It turns out that a jerk is like a protest of the motor :)
Regassing or clutch?
So I recommend that you regularly, at every downshift, use the throttle and preferably with double squeeze clutch pedals. With the help of re-gassing, you will change gear faster, smoother and safer for both traffic, and for car parts than with a smooth release of the clutch pedal. Of course, it’s difficult to master gas recirculation, but if you do it, then, I’m afraid, you will like it, so much so that you won’t tear it off! And then you won’t be imprisoned for an automatic machine :)))
Toe Forever!
By the way, the overdrive (in English: toe) came to us from the good old fifties, from trucks that did not have synchronizers and it was impossible to turn on the gear without overdrive in principle. Therefore, today sometimes there is a point of view that, they say, regassing is an anachronism, greetings from the past, and that any modern car handles downshifts well without over-revving. If you think so, then let's go back to the second paragraph of this article and once again turn on the lower gear without re-gassing. And for greater clarity, let's switch to 50 km / h not in second, but immediately in first gear. Just choose a quieter and wider place on the road, otherwise you will fly away from the road, it won’t seem enough ...
I would also add that re-gassing is an integral part of the arsenal of tricks of any professional racer. So if you're planning on doing sports driving, regassing for you is a must-have! Try it, keep it up!
And if you need practice - come to the courses "Magic of shifting" or "Driving on a race track". For novice drivers, the City Driving course is more suitable, and for advanced drivers, I can also advise you to take our school's exclusive course: MBA Driver's Course: Driving Mastery.
Even if you are not going to comprehend the heights of racing driving, in any case, gas is an element of driving skill and the calling card of a competent driver. I recommend!
With shifting and downshifting - everything, and in the next article I will finally tell you
