The Transfer case is part of the four-wheel-drive drivetrain, all-wheel-drive, and some other axle-powered vehicles. The transfer case transfers power from transmission to the front and rear axles using the drive shaft. It also syncs the distinction between front and rear wheel rotation, and may contain one or more sets of low range gears for off-road use.
Video Transfer case
Function
- The transfer box receives power from the transmission and sends it to the front and rear axles. This can be done with a gear, hydraulics, or chain drive. In some vehicles, such as four-wheel drive trucks or vehicles intended for off-street use, this feature is controlled by the driver. The driver can place the transfer case to "two-wheel-drive" or "four-wheel-drive" mode. This is sometimes achieved by way of a shifter, similar to a manual transmission. In some of these vehicles can be operated electronically by switch instead. Some vehicles, such as all-wheel-drive sports cars, have transfer cases that can not be selected. Such transfer cases are permanently "locked" into an all-wheel-drive mode.
- Transfer cases designed to allow normal road use synchronize the difference between front and rear wheel rotation, in much the same way as the differential action on the given shaft. This is necessary because the front and rear tires never rotate at the same speed. Different levels of tire rotation are generally due to different tire diameters (because the front and rear tires definitely wear at different rates) and different gear ratios in front and back differentials because manufacturers will often have slightly lower ratios in front vs. rear to help with controls (such as 3.55: 1 in the rear differential and 3.54: 1 in the front differential). If the transfer case does not make a difference between two different rotation levels, the binding will occur and the transfer case may become damaged. This is also why transfer boxes that are not designed for road use will cause problems with driveline windup if driven on drier sidewalks.
- A transfer case designed for off-road use can lock the front and rear axles mechanically when needed (eg if one of the axles is on a slippery surface or trapped in mud, while others have better traction). It's the same as a differential key.
- The transfer box may contain one or more sets of low-gear sets for off-street use. Low range gear is activated with shifter or electronic switch. In many transfer cases, this shifter is the same as the one choosing 2WD or 4WD operation. Low range gear allows the vehicle to drive at a much slower speed while still operating within the range of power/RPM bands that can be used from the machine. It also increases the available torque in the axis. The low distance gear is used for very poor road conditions, pulling heavy loads, driving on uncomfortable roads, and extreme off-road maneuvers such as rockcrawling. This feature is often absent in all-wheel-drive cars. Some very large vehicles, such as heavy equipment or military trucks, may have more than one low distance gear.
Maps Transfer case
Type
Transfer cases used on off-road "off-road" part-time vehicles such as trucks, truggies, rock-crawling vehicles, and some military vehicles generally allow drivers to choose 2WD or 4WD, as well as high or low gear. range. Used in sports cars and performance sedans are usually "transparent" for the driver; no shifter lever or select.
Movement type
Moving gears
There are two different types of internal power transfer mechanisms found in most transfer cases. Gear-driven cases use gear sets to push front or front front and rear driveshafts. These are generally robust, heavy units used in large trucks, but currently there are some cases of gear drives in production for passenger cars.
Chain-driven
Chain-driven transfer cases use chains to push most often only one axle, but can push both axles. Chain-driven transfer cases are quieter and lighter than those driven by teeth. They are used in vehicles such as compact trucks, full-size trucks, Jeep and SUVs. Some off-road driving fans modify their vehicles to use dental transfer cases, receive extra weight and noise to gain the extra power they normally provide.
Home type
Married
Cases of transfer are also classified as "divorced"/independent or "married". The married transfer case is locked directly to the transmission, usually between the transmission output shaft and the rear or main driveshaft. Sometimes married transfer cases are an integral part of the transmission and the two components share the same housing or "case", as is commonly found in recent Subaru products and some other all-wheel-drive cars.
Enlightened/independent
A separate or separate transfer case is completely separate from the transmission. It lies farther down the driveline than the case of a married transfer and is connected to the transmission output shaft by a short driveshaft. Independent transfer cases are used on very long wheelbase vehicles, such as commercial trucks or military trucks.
Type shift transfer case
M.s.O.F.
Manual Shift The On-the-Fly transfer case has a selector levers on the back side of the driver's side holder and may also have two sealed automatic axle-locking hubs or two manual front axle hub selectors "LOCK" and "UNLOCK" or "FREE". To use a four wheel drive system, the vehicle must move at low speed, the speed at which 4x4 can be used depends on the vehicle. This is only for setting the high four-wheel-drive. To use the low four-wheel-drive setting, the vehicle must be stopped and the transmission must be shifted to neutral, then low-wheel-drive low can be selected.
E.S.O.F.
The On-the-Fly Electronic Transfer (ESOF) transfer case has a switch or a selector button mounted on the dashboard with a closed front-end automatic shaft hub or flanged drive. Unlike manual transfer cases, this system has a motor transfer case. To use the four wheel drive system the vehicle must move at a lower speed, the speed at which 4x4 can be involved depends on the vehicle. This is only for setting the high four-wheel-drive. To use the low four-wheel-drive setting, the vehicle must be stopped and the transmission must be shifted to neutral, then low-wheel-drive low can be selected.
See also
- NP-205
- AMC/Jeep Transmission
- Jeep four-wheel drive system
- Mitsubishi Super Select
References
Source of the article : Wikipedia
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