Every driver heard the sound of the gear shift, but few people think about the most complex processes occurring inside the metal crankcase at this moment. Transmission box It is the link between the engine and the wheels, allowing the car to move from a place and develop high speed. Without this assembly, the engine’s torque would be either too weak to start or too excessive to drive on the track.
Inside the case, a complex system of gears, shafts and couplings hides, which interact with mathematical precision. The principle of operation is based on a change in the gear ratio, which allows you to vary the traction force depending on road conditions. Understanding how this mechanism works will help you take care of the technique and notice signs of wear and tear earlier.
The modern industry offers a variety of transmission options, from classical mechanics to complex robotic systems. Driver. You don’t have to be a design engineer, but a basic knowledge of the physics of the process will help you avoid fatal errors in operation. Let’s look at what exactly happens inside the node when your hand reaches for a lever or your finger touches the steering lobe.
The main purpose and tasks of the transmission
The main function of any gearbox is to convert the torque coming from the crankshaft of the engine. Internal combustion engines have a limited range of revolutions in which they are able to produce useful power. If the wheels were rotated directly from the engine, the car would either stall at the start or could not exceed the speed of the pedestrian at higher speeds.
The second major challenge is to ensure that the vehicle can be reversed. The design of the engine involves rotation of the crankshaft only in one direction, and it is the mechanisms P.C. allow you to reverse the direction of rotation of the output shaft. This is achieved by introducing an additional intermediate gear into the engagement, which changes the rotation vector.
⚠️ Attention: Turning on the reversing gear on many mechanical boxes without the car stopping completely can cause the gears to collapse instantly, as these nodes often lack synchronizers.
Also, the transmission allows you to disconnect the engine and driving wheels without stopping the engine. This is necessary for idling when the car is standing and the engine is running. In automatic boxes, this function is performed by a hydrotransformer or a friction packet, and in mechanics, a clutch, which, although a separate node, works in an inseparable connection with the box.
Key elements of the transmission design
The internal transmission device may vary depending on the type, but the set of basic elements remains similar. The basis is a durable crankcase in which the shafts are placed. In the classical scheme, there are usually three of them: primary (lead), secondary (followed) and intermediate. They are fixed or freely rotated. gears different diameters.
Synchronizers are used to transmit rotation without impacts and jerks. These details align the speed of rotation of the gear and shaft before they are connected. Without synchronizers, shifting gears on the move would be impossible without a double clutch squeeze, and the resource of the cogs would be calculated in thousands of kilometers.
- 🛠️ Shaft: steel rods, transmitting rotation, made of high-strength alloys.
- 🛠️ SHIPS: gear wheels of different sizes, which determine the gear ratio.
- 🛠️ Synchronizers: Friction couplings that ensure smooth switching.
- 🛠️ Selection mechanism: a system of levers and forks that moves the couplings of the inclusion.
All these processes are controlled by the mechanism of selection and shifting of gears. In mechanical boxes, this is a system of rods and cables coming from the lever in the cabin. Automatic and robotic versions are responsible for this. hydraulics and electronic actuators, which at the signal of the computer compress the desired packets of frictions or move the plugs.
Why don't the gears break instantly?
The gears are made by cementation – saturation of the surface layer with steel with a high carbon content. This makes the outer layer very hard, and the core of the part remains viscous, which allows you to withstand colossal impact loads without breaking.
The principle of operation of a mechanical box (ICP)
Mechanical transmission is considered the standard of reliability and ease of understanding processes. The driver makes the decision to switch, based on engine speed and speed. When you squeeze the clutch pedal, the connection between the engine and the box breaks, allowing the gears to move freely.
Inside the crankcase are constantly engaged pairs of gears, but they rotate the shaft only when the corresponding coupling blocks them. Moving the lever, you through the system of forks move the clutch, which with its teeth enters into engagement with the crown of the gear. At this point, the gear tightly binds to the shaft and begins to transmit torque.
The critical point is the work of the synchronizer, which, for a split second before blocking, equalizes the rotation speed of the parts, preventing the teeth from hitting. That is why on a serviceable box, transfers are turned on gently and without crunch. If you hear a grinding sound, it means that the synchronizer is worn out or you are throwing the pedal too sharply.
☑️ Diagnostics of mechanics
The effectiveness of mechanics is the direct transfer of force without loss to the friction of liquids or slipping of belts. This ensures a high level of Efficiency And excellent fuel efficiency. However, the comfort of such driving depends solely on the driver’s skills and the state of the clutch.
How does the automatic transmission (ACP) work?
In the classical hydromechanical automatic, the role of clutch is performed by a hydrotransformer. It is a device consisting of two turbines (pump and turbine) that do not touch mechanically. Energy transfer occurs through a special fluid flow – ATF. At low speeds, the liquid circulates freely, allowing the motor to work at idle, and with increasing speeds, the flow is compacted and rigidly binds the shafts.
The choice of transmissions in the automatic transmission is responsible for the planetary series. It is a complex system of gears located around the central axis. Unlike mechanics, where the gears move, here they are in constant engagement. Switching occurs by stopping or rotating certain elements of the series using friction disks.
- ⚙️ Hydrotransformer: It provides a smooth start and extinguishes the jerks.
- ⚙️ Planetary mechanism: Changes the gear ratio without breaking the power flow.
- ⚙️ Hydroblock: pressure distributor, which controls frictions.
- ⚙️ EBU: The electronic brain that determines the moment of switching.
All this farm is managed by an electronic control unit that reads data from dozens of sensors. It analyzes the position of the throttle, the speed of the car, the angle of the road and even the driving style. Based on this data, pressure is applied to the desired channels of the hydroblock, compressing the friction packets.
⚠️ Attention: Switching the selector from the position "D" (Drive) to "R" (Reverse) on the move is strictly prohibited. This causes a hydrostroke and instantaneous destruction of friction disks and planetary series.
Modern. machine-guns They can have 8, 9, and even 10 steps. Such a large number of gears allows you to keep the engine in a narrow range of maximum efficiency, which has a positive effect on fuel consumption and ecology. However, the complexity of the design requires strict adherence to oil replacement intervals.
Features of robotic boxes and variators
Robotic transmissions (RCPPs) are structurally closer to the mechanics than to the automatic. In fact, it is the same mechanical box, but the clutch and switching of plugs are engaged in electronic actuators or hydraulics. This allows you to combine the fuel economy of the mechanics with the comfort of the machine.
There are single-clutch robots and preselective boxes (e.g. DSG). In preselective versions, two shafts are used: one for even gears, the other for odd ones. While the car is moving in second gear, the third is already on the second shaft and is waiting for its moment. The switching happens instantly, breaking the power flow for only a fraction of a second.
The CVT is radically different from the lack of fixed gears. It is based on two sliding cones and a belt (or chain). By changing the distance between the cheeks of the cones, the system smoothly changes the diameter along which the belt passes. This provides a continuous change in gear ratio.
| Type of PPC | Resource (km) | Comfort. | Fuel consumption | Cost of repair |
|---|---|---|---|---|
| Mechanics (IPT) | 250 000+ | Low. | Low. | Low. |
| Automatic (ATM) | 200 000 - 300 000 | High-pitched | Medium. | Tall. |
| Robot (DSG/RCPP) | 150 000 - 200 000 | Medium. | Low. | Tall. |
| CVT (CVT) | 150 000 - 200 000 | High-pitched | Low. | Medium/High |
Variators provide perfect smoothness of stroke, as the engine can operate at constant speeds while the car accelerates. However, they do not like sharp starts with slippage and high loads, since the belt can slip, causing wear of the cones.
The choice of the type of transmission depends on priorities: mechanics - for reliability and economy, automatic - for comfort in the city, robot - a compromise for dynamic driving, CVT - for quiet urban operation.
Typical malfunctions and their symptoms
Even the most reliable transmission It's subject to wear and tear. One of the first signs of trouble is difficulty turning on gears or extraneous sounds. If the lever is tight or the gears are turned on with the crunch, the most likely problem is the clutch, drive cables or wear of the synchronizers.
Noise, hum or howl coming from under the bottom, often indicates insufficient level of oil or wear of bearings of shafts. In automatic boxes, the kicks when switching speak of contamination of the hydroblock or low levels of ATF fluid. Ignoring these symptoms can lead to costly repairs to the entire node.
- 🔊 GUG: wear of bearings or lack of lubrication.
- 🔊 Knocking: wear of forks or fixers of the selection mechanism.
- 🔊 Oil stains: violation of the sealing of the gums.
- 🔊 Tricks: Problems with the hydrotransformer or clutch.
It is important to monitor the color and smell of the oil. In mechanics, it must remain transparent, in the machine - red or green (depending on the specification). Blackened oil with the smell of burns indicates the combustion of friction linings and requires immediate diagnosis.
⚠️ Attention: Overheating of transmission oil reduces its viscosity at times, which leads to oil starvation of friction nodes. When towing heavy loads or moving in traffic jams, monitor the temperature of the checkpoint.
Rules of operation and extension of the resource
The life of the transmission depends on the driving culture and timely service. The basic rule for all types of gearboxes is to stop the car completely before switching between forward and backward driving modes. The inertia of the rotation of the shafts is able to cut the teeth of the gears in a fraction of a second.
For mechanical boxes, it is important not to keep your foot on the clutch pedal unnecessarily. Even a light touch leads to slipping of the disc and its accelerated wear. In the winter, mechanics and robots need to be warmed up, having traveled the first kilometers at low speeds, so that the oil dispersed to all nodes.
Automatic boxes require regular fluid replacement. Despite the manufacturers’ claims about the oil “for the entire life”, real practice shows that the interval of 60,000 km is optimal for maintaining health. hydroblock and frictions. The use of non-original fluids can lead to incorrect operation of the valves.
Compliance with simple rules will avoid premature failure of this expensive unit. Remember that repairing or replacing a gearbox is often more expensive than timely maintenance and tidy driving.
Why is the gearbox howling to the cold?
Howling on cold is often associated with thickening of transmission oil. The pump cannot quickly pump the viscous liquid, and the parts work in oil starvation mode. Also, the cause may be wear of the bearings of the primary shaft, the gaps in which are cold manifested more strongly.
Can I tow a car with an automatic transmission?
Towing a car with an automatic transmission is possible only for short distances (up to 50 km) and at low speed (up to 40-50 km / h). When towing, the shafts of the gearbox rotate, but the pump does not work, which leads to overheating and destruction of rubbing vapors without lubrication.
How often should I change the oil in the MCU?
In mechanical boxes, it is recommended to change the oil every 60-80 thousand kilometers of run. Although the design of the manual gearbox is simpler, the wear products of the gears (metal shavings) over time saturate the oil and begin to work as an abrasive, accelerating wear.
What is an oil starvation checkpoint?
This is a condition in which a sufficient amount of lubrication does not come to the rubbing parts. Causes: low oil levels, filter clogging (in automatic transmission), oil pump failure or use of oil with inadequate viscosity at extreme temperatures.
Why do transmissions turn on with effort?
Tight gears can be caused by freezing of lubricant in the drive cables (winter), wear of spherical hinges of the backstage, improper adjustment of the drive or critical wear of synchronizers inside the box itself.