243 New Venture Gear Transfer Case General Description

The Model 243 is a part-time four-wheel drive system.

The Model 243 will allow the driver to select between the following ranges:
- 4-wheel drive low range (4LO)
- 4-wheel drive high range (4HI)
- 2-wheel drive high range (2HI) Three electric transfer case push button selector switches enable the driver to select the range position. The switches are located in front of the driver on the console. The control switches send electronic requests to the electronic Transfer Case Control Module (TCCM). The TCCM positions the transfer case accordingly.

The two-piece aluminum case of the Model 243 contains the following components:
- The front output shaft
- The rear output shaft
- Two drive sprockets
- The shift mechanism
- The planetary gear assembly.

The drive chain connects and operates the drive sprockets.

The planetary assembly consists of the following components:
- A six-pinion carrier
- An annulus gear.

The planetary assembly provides the four-wheel drive low range when engaged.

The gear reduction ratio is 2.72:1 in this range.

IDENTIFICATION

An identification tag is attached to the rear half of the transfer case. The tag provides the following information:
- The transfer case model number
- The low range reduction ratio
- An assembly number

The information on this tag is necessary for servicing this transfer case. If the tag is removed or becomes dislodged during service operations, keep the identification tag with the unit.

POWER FLOW

Input torque is transmitted to the transfer case gear train through the transfer case input gear. This transfer occurs in all drive range positions.

Torque transmission in 2HI range occurs as follows:
- Torque is transmitted from the input gear to the range shift hub and the mainshaft.
- Torque flow continues through the slip yoke.
(The slip yoke is splined to the mainshaft.)
- Torque flow continues to the rear propeller shaft and axle.

In the 2HI range, the mode synchronizer remains in the neutral position and does not lock the drive sprocket to the mainshaft. As a result, torque is not transferred to the driven sprocket.

Torque transmission from the input gear to the mainshaft is the same in the 4HI range. However, in the 4HI position, the mode synchronizer sleeve is shifted into engagement with the clutch teeth of the drive sprocket. This locks the drive sprocket to the mainshaft through the synchronizer. The drive chain then transmits the torque through the drive sprocket to the driven sprocket. Since the front output shaft is splined to the driven sprocket, torque flows through the output shaft to the front propeller shaft and axle. This results in high range four-wheel drive.

In the 4LO range, the range shift hub is shifted into engagement with the planetary carrier. This causes the input gear to rotate the planetary pinions inside the annulus gear. The planetary carrier, range shift hub, and mainshaft rotate at a gear reduction ratio of 2.72:1.