The so-called transfer case, engine power is allocated to a device, the output power to the rear axle, or outputs the same to the front / rear axle. As can be seen from this perspective, the transfer case is actually a four-wheel accessory on. With the development of four-wheel drive technology, the transfer case has also been engaged in change, and gradually formed styles of transfer case, matching the four-wheel different demands, their basic principle and function are also different from each other .
1. The transfer case noun interpretation
The so-called transfer case, engine power is allocated to a device, the output power to the rear axle, or outputs the same to the front / rear axis. As can be seen from this perspective, the transfer case is actually a four-wheel accessory on. With the development of four-wheel drive technology, the transfer case has also been engaged in change, and gradually formed styles of transfer case, matching the four-wheel different demands, their basic principle and function are also different from each other .
2. Basic describes a purely mechanical transfer case
is usually four-wheel drive cars can drive two, into four-wheel drive off-road vehicle. Four-wheel drive transfer case is a purely mechanical device. Transfer case at the time of such a structure hanging 4WD mode, the front and rear axles are connected to the steel, power allocation before and after 50:50 can be achieved by very advantageous for improving vehicle. Also due to its purely mechanical structure, high reliability, which often lack the rescue in wilderness travel models is essential. Even now, there are still a large number of hardcore off-road car using this transfer case. On the transfer case Dangba such models, we will see the 2H, 4H, N, and the switching gear 4L. When hanging 2H, this type of vehicle is a rear drive, after the power of the engine through the transmission, is connected to the rear axle via a propeller shaft directly. And the role of the transfer case, the transmission is in, and then led out to an output terminal, and by silent chain, power is transmitted to the output shaft of the front axle. Of course, this is not directly connected, otherwise you can not switch the drive 4WD and 2. In fact, it is to separate and connected by two sets of gears, its structure and principle is similar to a shaft of the gearbox shaft and II. Handover, transfer case Dangba pulled by the front fork shaft with the power on and off. And mainstream gearbox synchronizer with different parts of the switching device is not synchronized, it takes exactly matching speed and the wheel speed. This is the basic principle of this transfer case.
But the reality is not so simple, in order to improve performance through, there will be such a transfer case urging gear, i.e. on Dangba 4L mode. On the gearbox, there is a greater gear ratio gear, the gear when hung, can provide a much higher ratio than the main drive for everyday driving. We found that when IWhen they need to hang 4L, you must be a N block, then the transmission power of each shaft will separate, while hanging 4L, will turn on the gear tooth ratio of greater. This switching process, there is no synchronizer.
know this principle, let us look at the characteristics of each mode of operation of such a transfer case. Riders familiar with traditional off-road vehicles are known, which transfer case, when switching between 2H and 4H, do not need to stop, generally can switch at 80 km / h speed. And switching to 2L, you must stop switches, or simply do not hang in, which is why?
Whether 2H mode or 4H mode, the power has been turned on and the rear axle, rear wheel exact match speed with the engine speed. At this time, as long as the wheels do not slip, the wheel speed of the front and rear wheels are the same, so when switching between 2H and 4H, the rotational speed of the output shaft before the engine speed is matched, even without synchronizers, also can to switch. Thus between 2H and 4H, the mode switching mode, can be carried out entirely in the road, no parking switch. But to the conversion 4L mode, the situation is completely different.
is switched from 4H to 4L mode, the transfer case is switched to the first N range, then the engine power to each of the wheels are turned off, the engine into an idle condition. At this time, if linked to 4L, the engine rotational speed and the wheel speed of the wheel will be difficult to match, equivalent to a vehicle without a synchronizer to hang in a traveling block, which is obviously very difficult.
This division is no differential between the front and rear axles movable box, so the only high adhesion road driving hanging 2H, 4 drive mode only in the non-paved road and a gravel road to improve by nature and design. Therefore, using this four-wheel drive transfer case are generally hardcore off-road vehicle, it is very powerful non-paved road in the road, but the road is flat.
The early four-wheel drive, is completely rely on manual switching, developed later, there have been four-wheel drive electric switch, its basic principles and manual switching of four-wheel drive is the same, All but nothing is done by switching the motor.
3. Ultra selected from the four-wheel drive transfer case substantially description
This is called Mitsubishi, also has been seen as Mitsubishi housekeeping techniques. From the look Dangba transfer case, it is more like a traditional four-wheel drive systems, except that it is provided with a central differential. When 4H hang time, not only in high speed gravel surface, can be achieved road four-wheel drive functions on a general road. And it provides 4HLC and 4LLC option, four-wheel drive mode is locked center differential lock, at this time, it features four-wheel drive of 4H and 4L is the same.
The reason why the ultra selected from Mitsubishi called, because it is actually selectable four-wheel drive system than all have multiple ranges. General full-time four-wheel, four-wheel drive select can only travel in four-wheel drive is not required when such an approach is clearly not the economy; and timely four-wheel drive can be achieved though two drive, but when the four-wheel drive can not achieve true full performance four-wheel drive; four-wheel drive would not have said, that he could not achieve road four-wheel drive. And all these super selective four-wheel drive can be selected – think the economy is good, hung 2H, want to hang on road four-wheel drive 4H, want to achieve with the traditional four-wheel drive as through sex, hung 4HLC or 4LLC.