New Venture Gear Model 243
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 planetary gear assembly |
The drive chain connects and operates the drive sprockets.
The planetary assembly consists of the following components:
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 |
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.
