Fans of outdoor activities and professional researchers of remote corners of the planet know: an ordinary crossover, even with all-wheel drive, is powerless before serious off-road. It is at such moments that the technical feature that separates a real SUV and just a high car comes to the fore. It is about availability. downshift in the transmission.
This system allows the wheels to rotate at a lower speed, but at the same time transmits a huge torque to them. For the driver, this means the ability to get out of a deep track, overcome a steep climb or pull a heavy trailer where a normal car would have stalled long ago. Understanding the principles of this system is critical when choosing a vehicle for harsh operating conditions.
In this article, we will discuss in detail which models are equipped with such a mechanism, how it is arranged and why the presence of a “distribution” with a demultiplicator is a key factor in cross-country. You will learn about the nuances of operation and understand why you may need such a feature, even if you rarely move off the pavement.
What is a downshift and why is it needed?
At the heart of any transmission is the principle of transferring rotation from the engine to the wheels. However, the gear ratios of the main gearbox are designed primarily for traffic on paved roads. When a car hits a viscous ground, sand or steep slope, there is too much resistance. The engine cannot develop enough traction in standard gears, and the wheels begin to stall without moving the car from a standstill.
Here comes the work. demultiplifier - a special gearbox, which further reduces the speed transmitted to the wheels. If the first gear of the main box has a coefficient, for example, 3.5, then the inclusion of the "downshift" multiplies this value by another 2 or 3. As a result, the wheels create the effect that the car has a "zero" or "half-first" gear, providing maximum traction at minimum speed.
The use of this regime allows:
- 🚙 Overcome deep snow or sand without the risk of getting stuck as the wheels spin slowly and do not bury.
- 🏔️ Climb steep slopes at a constant low speed without pressing on the gas.
- ⚓ Tow heavy loads or act as a tractor for other vehicles.
It is important to understand that downshift It is not just an additional step in the box, but a separate node, most often part of the transfer case. In modern systems, the control of this process can be mechanical (lever in the cabin) or electronic (puck or button).
Types of all-wheel drive systems with a downgrade
Not all 4x4 systems are the same, and having all-wheel drive does not guarantee the presence of a lowered row. In the automotive world, there is a clear division into Part-Time, Full-Time and plug-in drive systems, where the demultiplier plays a different role.
The most common scheme for real SUVs is Part-Time. In such cars, in normal conditions, only the rear (rarely front) drive works. When the road becomes bad, the driver rigidly connects the front axle and simultaneously or separately activates the downshift. A classic example is this. Jeep Wrangler or Toyota Land Cruiser 70. There is no center differential, so you can not drive with all-wheel drive on the asphalt - this will lead to a breakdown of the transmission.
The other type is permanent all-wheel drive (Full-Time). Here, between the axles is a differential, allowing the wheels to rotate at different speeds, which is necessary for turns on a solid road. The downshift in such systems often blocks this differential or operates through a separate planetary mechanism. And the brightest representatives are Land Rover Defender and Mercedes-Benz G-Class.
There are modern electronic imitations, but they are not full-fledged mechanical downshift. Some crossovers use towing wheel braking and high gears to create the illusion of traction, but against a real "handout" they are powerless.
⚠️ Warning: Never attempt to turn on mechanical downshift at high speed. This will result in instant and costly destruction of the gears of the transfer case. You can only switch after the car has stopped completely.
Overview of popular SUVs with demultiplifier
The market of cars equipped with a full-fledged downgrade, gradually narrowing, giving way to crossovers, but the real "fighters" are still available to buyers. The choice depends on the budget and the desired level of comfort.
In the segment of the legendary classics, the undisputed leader remains the family. Toyota Land Cruiser (especially the 70, 100, 200 and new 300 series). Their reliability and efficiency Full-Time 4WD With locks and downs, it became a benchmark. Also, you can't miss mentioning. Land Rover DefenderIt combines advanced electronics and a classic low gear transfer case.
A more affordable but equally effective option is UAZ Patriot.. It is one of the few modern frame SUVs where the downshift is controlled by a classic lever, and the design is simple and maintainable. For those looking for a compact but evil apparatus, a great choice will be Suzuki Jimny. Despite its small size, its transmission allows you to work wonders off-road.
Among the American ikon stands out Jeep Wrangler and its more civilian version Jeep Wrangler Unlimited. System system Rock-Trac or Command-Trac It offers some of the lowest reduction rates on the market, making them ideal for climbing stones.
When choosing a used SUV, be sure to check the operation of the lever or button for the inclusion of a reduced gear. The mechanism should be turned on clearly, without crunch and jamming, and the indicator on the panel should burn instantly.
Technical characteristics and comparison of models
When choosing an off-road car, it is important to pay attention not only to the presence of a reduced gear, but also to its reduction coefficient. The higher it is, the more torque the wheels get. Let’s compare the key parameters of popular models.
The table below shows the data on the reduction rates and the type of drive for the various cars. These figures show how much torque increases when Low mode is activated.
| Model model of the car | Type of drive | Lower coefficient. transmission | Management |
|---|---|---|---|
| Jeep Wrangler Rubicon | Part-Time | 4.0 : 1 | Lever/Electro |
| Toyota Land Cruiser 200 | Full-Time | 2.566 : 1 | Lever |
| UAZ Patriot. | Part-Time | 1.938 : 1 | Lever |
| Suzuki Jimny | Part-Time | 2.268 : 1 | Lever |
| Land Rover Defender (New) | Full-Time | ~3.0 : 1 | Electronically |
As the table shows, American jeeps often win on the reduction ratio, making them the kings of climbing. Japanese and British schools are betting on a balance between passability and behavior on the track. Coefficient - not the only parameter; also important clearance, angles of entry and the presence of differential locks.
It is worth noting that in modern cars, the control can be completely electronic. The driver simply turns the puck and the servo drives inside the transfer case switch. It’s convenient, but in extreme conditions, mechanics are often more reliable.
Why are the odds so different?
The difference in coefficients is due to the purpose of the car. For Jeep Rubicon, created for extreme offroads, maximum traction at minimum revs is important. For the Land Cruiser, versatility is more important, so that the car feels comfortable on the highway and in the mud.
How to use the reduced transmission correctly
Having a powerful tool requires you to be able to use it. Improper operation of the demultiplicator can lead to an accident or breakdown. The main rule is: downshift It is used only when the car lacks traction in the first gear of the main box, or when it is required to move at a very low speed (slide).
Before the Low Range mode is turned on, the car must be completely stopped. In some modern models, it is allowed to switch on the go at speeds up to 5 km / h, but it is better to be safe and stop. After turning on the transmission, wait for the corresponding indicator on the dashboard to light up. Only then can the movement begin.
Reduced gear requires a change in driving style. You don't have to push the gas. The engine will run at higher revs at the same speed and the machine will be very sensitive to the accelerator pedal. Often it is enough to just release the brake pedal so that the car begins to confidently climb up.
- 🛑 Stop the vehicle completely before switching.
- ⚙️ Squeeze the clutch (on the manual transmission) or transfer the selector to neutral (on the automatic transmission), if the instruction requires it.
- 🔘 Activate the lever or button to enable the lowered row.
- ✅ Make sure the indicator is on fire.
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Do not forget to turn off the low gear mode immediately after overcoming the difficult area. Riding on asphalt with the included "downsizing" will lead to overloading of the engine and transmission, as well as to rapid wear of rubber.
☑️ Algorithm for incorporation of a downgrade
Maintenance and frequent transfer box problems
A dispensing box with a demultiplier is a robust node, but it also requires attention. The main enemy of such systems is the lack of timely oil change and overheating. Owners often forget that there is also oil in the handout that needs to be changed.
Among the frequent problems can be identified:
- 🔊 Noise and hum when moving, indicating wear of bearings or gears.
- 💧 The leaks of the ossels shafts, especially after long fords, when the hot knot cools sharply in the water.
- ⛓️ Chain jamming (in chain dispensers) or difficulty with switching due to oxidation of contacts or mechanical catching of plugs.
To prolong the life of the node, it is recommended to check the oil level every 15-20 thousand kilometers. If you are actively using the car on the road, the intervals of replacement of technical fluids should be reduced by half. Use only those oils recommended by the manufacturer, often these are special formulations with labeling. ATF org-shift 75W-90.
⚠️ Attention: After overcoming deep fords, be sure to dry the brakes and check the transfer case sapons. The ingestion of water inside through the sapoon when cooling is a common cause of emulsion in oil and corrosion.
Regularly changing the oil in the transfer case is the cheapest way to avoid major repairs to the unit, the cost of which can be a third of the cost of the car.
Electronic imitation versus mechanics
In recent years, automakers have been looking to simplify designs. On many crossovers and even some SUVs, mechanical handout gives way to electronic couplings. The question is, can electronics replace the old mechanical demultiplifier?
Systems like Haldex or multi-plate couplings paired with powerful engines really work wonders. They can throw the moment on wheels with good grip. But they have a limit to their strength. With prolonged slipping, the clutch overheats and shuts down, leaving the car helpless. Mechanical downshift It does not warm, is not afraid of dirt and works until the metal breaks.
There are hybrid solutions, for example, in Mercedes G-Class or Jeep Grand Cherokeewhere electronics control mechanical locks. It's the perfect balance. But if you choose a machine for expeditions to places where there is no communication and help, having a physical connection between the lever and the gears gives a huge psychological and technical advantage.
Ultimately, the choice depends on the tasks. For snow in the yard and the cottage will be enough and electronic imitation. For taiga, mountains and swamps, only proven mechanics are needed.
Can I install a downgrade on a regular crossover?
Technically, it is possible, but economically impractical. Replacement of the entire transmission, installation of transfer case, driveshafts and strengthening of the body will be required. The cost of such work will exceed the price of the car. It is easier to buy an originally prepared SUV.
Is it harmful to go on a low gear on the highway for a long time?
Yeah, it's extremely harmful. The engine will operate at maximum speeds, which will lead to its overheating and increased fuel consumption. The speed of movement will be limited (usually up to 40-60 km / h), and the engine life will be developed very quickly.
Why does the car not accelerate when the lowering is turned on?
Because the main task of the demultiplicator is to increase torque, sacrificing speed. The gear ratio becomes very large, so even at high engine speeds, the wheels rotate slowly. This is a normal working characteristic of the regime.
Do I need a lowering for snow in the city?
In 95% of urban winter operation, downshift is not required. Enough quality winter tires and careful driving. The lowering is useful if you are stuck in a snowdrift in the yard or parked on an uncleaned roadside.