Transfer Case Types

Transfer Cases Gear And Chain Driven, Part And Full Time Plus Active On Demand

Rok Trac

Dana 300


Gear Or Chain Driven

The gear driven transfer cases use a gear set to drive the front and rear drive-shafts. They are stronger, heavy units that are usually found in larger trucks. The hard-core four-wheelers prefer the gear-driven because they can withstand greater torque without breaking. Most present-day transfer-cases are chain-driven, and are not as strong, weigh less, and are quieter than the gear-driven They are usually found in smaller trucks, cars etc.

Rok Trac

NP 241C Part Time


It used to be that almost all transfer cases fell into one of two categories: part-time or full-time. A part-time transfer case is one that can shift between two- and four-wheel drive, allowing the driver to select the mode that best suits road conditions. Wear on the front-drive components is reduced with a part-time system, since they’re not always engaged, and fuel economy is generally better for the same reason.

Rok Trac

Np 231 Part Time


A List Of Part Time Transfer Cases

  • NV 231
  • NV 231HD
  • NV 241
  • NV 241HD
  • NV 261
  • NV 261HD
  • NV 261SHD
  • NV 271**

Full Time Plus Part Time

Rok Trac

NP 242_Full Time


A full-time case is permanently in four-wheel drive, so no action on the driver’s part is required to engage the system. In order to use a full-time transfer case on hard-packed surfaces without binding the driveline, the case must be built to allow driveline slip between the front and rear wheels. Some (like the NP203) contain differential gears inside the case, while others use some sort of clutch or viscous coupling between the T-case and the front driveshaft. In both cases, there is typically a means to lock the slipping mechanism for a true 50/50 torque split when conditions warrant.

Rok Trac

NP 242F_Full Time

A list of additional part time Transfer cases

  • NV 124
  • NV 125
  • NV NV 149AWD
  • NV NV 249


NVG246 AUTOTRAC

Rok Trac

NVG 246 AUTOTRAC


The latest developments in transfer case technology include hybrids that combine full-time and part-time functions in one unit. Shown here is GM’s NVG246, otherwise known as the Autotrac system. It uses a number of sensors and its own computer to direct torque when in full-time mode, plus it has the traditional part-time 4-High and 4-Low modes as well. The Autotrac system is found on fullsize GM trucks and has made its way to the midsize TrailBlazer and Envoy SUV