|Last changed: 2000/01/01 00:00 / History||Edit|
Command-Trac was first introduced using the NP208 transfer case in the full-size Jeeps (SJ series) in 1980. The drive modes are the same as with the Dana 18 and 20 transfer cases: 2Hi, 4HI PT, and 4LO PT. The 4WD modes are not for use on high-traction surfaces such as dry roads. The NP208 was used through at least 1987.
More commonly, Command-Trac is used to refer to the NP/NV-231 or NP-207 transfer cases introduced along with the Jeep Cherokee (XJ) (XJ) in 1984. The system offers a chain-driven, aluminum, "shift-on-the-fly" transfer case. The "shift-on-the-fly" feature provides manual ease and assist while engaging 4WD. Command-Trac should only be driven in 4WD on low-traction surfaces due to the front and rear axles being locked together (no differential action in the transfer case). Driving in 4WD on dry pavement causes excessive wheel and drivetrain wear. Four-wheel modes are most commonly used for wet/slick surfaces or extreme weather conditions (rain, snow, etc.) (4H), towing (N), and off-road activities (4L).
There are reports of a modified version known as NP-231J HD which was supposedly (SP) a "heavy duty" version for the Jeep Grand Cherokee with V8 engines. The NP/NV-231 case is a chain-driven unit that takes 21- or 23-spline input shafts. The 23-spline was for the AX-15 transmission, and the 21-spline was used for the AX-5 and BA 10/5 transmissions. Low range for this case was 2.72 and high range was 1.00.
The Command-Trac HD transfer case was used in 6-speed Liberty KJ's from 2005–2007. Although sometimes referred to as the "NV(NP)231HD," the transfer cases are actually the 241 series used in full-sized trucks from other makers (241D or 241C). The Jeep version is labelled "NV(NP)241J." This is not the NV241OR transfer case found in the Jeep Wrangler Rubicon, which uses a 4.0 low range and has a reinforced case. Dodge uses a 241DHD, which has a reinforced case but the 2.72 low-range.
The Jeep Grand Cherokee/Commander line no longer offers a part-time transfer case option. The reason behind this was its poor sales along with an improved Selec-Trac. Selec-Trac and a simplistic Quadra-Trac had the convenience and comfort of "Full-Time" all wheel drive that Command-Trac lacked for "luxury" SUV's that did not require the more rugged part-time system.
The terms "Command-Trac" and "Selec-Trac" were used in other Jeep lines and refer to different transfer cases in those lines.
Rock-Trac is similar to url=http://www.jeep.com/en/4x4/index.html#RockTrack, |title=Jeep 4x4 Basics |publisher=jeep.com |date= |accessdate=2012-08-16}}</ref> In 2007 an electronic front sway bar disconnect was added and the locking differentials switched from air-actuation to electronic actuation.
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Selec-Trac was first introduced in the full-size Jeeps (SJ) in 1983 using the viscous limited-slip differential does; which allowed the vehicle to be driven in "4Hi" on dry pavement. It was used from 1983 to 1991 in some applications.
The AMC Eagle used the NP119 transfer case in 1980, a strictly full-time all wheel drive model. From 1981 to 1988, a similar system was employed, dubbed "Select-Drive", which allowed the vehicle to switch from all wheel drive to 2WD using the NP129 model transfer case. The NP129 contained a viscous coupling around an open differential for added traction in slippery conditions. The NP128 has also been found equipped in select model years, which does not feature a viscous coupling.
The NP228 Selec-Trac transfer case is closely related to the NP229. The only difference is that the NP228 does not have a viscous-type limited-slip coupling. It was used briefly in 1986.
The NP242 Selec-Trac transfer case debuted alongside the Fuel-Injected 4.0L Inline-6 in the compact Jeep Cherokee in 1987 (previous years used the NP228/229) It is a more common feature in the upscale Limited version and the XJ Jeep Wagoneer, and Jeep Wagoneer/Grand Wagoneer (SJ)
Selec-Trac II is similar to Selec-Trac I but uses a console mounted switch to control the MP3022 transfer case as opposed to a floor mounted lever. Selec-trac II also differs with its lack of a part-time 4WD setting.
The Borg-Warner system was replaced with a "New Process Gear" NP219-based chain-driven system in 1980. The NP219 Quadratrac transfer case was used in full-size Jeeps from 1980 through 1982. It offered the following modes: 4HiFT, 4HiPT, and 4LoPT. In full-time 4WD High a viscous limited-slip coupling is used between the front and rear output shafts.
In 1996 the NP249 was replaced with the Jeep Grand Cherokee (ZJ)
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Quadra-Trac II was introduced in 1999 and it employs a two-speed chain-driven traction control and replaced Quadra Trac I. In 2005 Jeep added traction control and replaced the thumb|right|200px|Quadra-Drive selector in a 1999 Jeep Grand Cherokee (WJ)
The Quadra-Drive system was introduced in 1999 and is based on the gerotor style limited slip differentials.
Quadra-Drive II uses the electronic limited slip differentials or ELSDs. Jeep added traction control in 2005 and starting in 2011 only a rear ELSD is offered, while the front has an open differential.
Freedom Drive is Jeep's four wheel drive system used in its compact crossover SUVs based on a front wheel drive platform, the Compass and Patriot. There are two versions of the basic Freedom Drive system for the US Market, called I and II.
Freedom Drive I(Edit)
Freedom Drive I is a light duty full-time electronically controlled GS Platform.
Active Drive I is a full-time four-wheel drive system that requires no driver input. This system under normal conditions sends all available torque to the front wheels while monitoring the speed of the front and rear axles. If the system detects that the front axle is moving more quickly than the rear axle then the system will send power through the power transfer unit to the rear axle until the speeds are the same.
Active Drive II(Edit)
Active Drive II includes all of the features of Jeep Cherokee (KL)
Active Drive Low(Edit)
Active Drive Low includes all of the features of Jeep Renegade (BU)
Active Drive Lock(Edit)
Active Drive Lock includes all the features of Jeep Cherokee (KL)
Selec-Terrain is a system designed to calibrate the vehicle to provide the best on-road and off-road performance; depending on which terrain mode is selected. The modes are selected by a dial located near the center console and have five settings: "Auto", "Snow", "Sport", "Sand/Mud" and "Rock". This system was first offered in the 2011 Jeep Grand Cherokee. It also comes standard on all 2014 Jeep Cherokees with four-wheel drive and all Jeep Grand Cherokees with a two-speed transfer case.
Have you seen a better description of Selec-Terrain on the web? Please send us the link to or post it in a comment below!
|Last changed: 2000/01/01 00:00 / History||Edit|
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