that it will drive the rear wheels at all times and drive the front wheels when needed.
The transfer case can be mounted in several ways in a vehicle. It can be a separate component mounted to the rear of the transmission and driven by a propeller shaft connecting it to the output of the transmission. It can also be a part of the transmission (fig. 11-10) and driven by a gear or by the output shaft of the transmission. The transfer case performs one or more of the following functions:
It transfers the transmission power to a point low enough so that a propeller shaft can be mounted under the engine and power the front axle.
It provides an output to power one or more rear axles.
It provides a high and low gear ratio for vehicles that do not have the necessary gear reductions in the transmission.
It provides arrangements for engaging and disengaging front-wheel drive and high and low ranges when applicable.
One of the mechanic's jobs is to repair transfer cases; this means diagnosing trouble, dismantling, inspecting, and reassembling the unit. If you become familiar with the method of repairing one particular transfer case, you should not have much difficulty repairing others.
The first indication of trouble within a transfer case, as with other components of the power train, is usually "noisy" operation. If an operator reports trouble, make a visual inspection before removing the unit from the vehicle. Check for such things as oil level, oil leakage, and water in the oil.
Make sure the shift lever linkages are inspected. If the shift lever linkages are bent or improperly lubricated, it will be hard to shift the transfer case or, in some cases, will make shifting impossible. Make sure other possible troubles, such as clutch slippage, damaged propeller shaft, and damaged axles, have been eliminated.
Worn or broken gears, worn bearings, and excessive end play in the shafts will cause noisy operation of the transfer case. When it is determined that the trouble is within the transfer case, have your personnel remove the unit from the vehicle for repairs.
Make sure the transfer case is thoroughly cleaned before disassembly of the unit begins. When the unit is disassembled, have each part cleaned with an approved cleaning solvent. Inspection of the individual parts should follow the same procedure as outlined for transmissions. Avoid waste by using old parts that are in good condition. Table 11-2 is a troubleshooting chart for transfer cases. As referenced in the chart, you should refer to figures 11-11, 11-12, 11-13, and 11-14 respectively.
Personnel who are not thoroughly familiar with a particular make and model of a transfer case should be supplied with a manufacturer's repair manual. Check the job frequently to be sure the proper adjustments and assembly procedures are followed.
Figure 11-10. - Transfer case to the transmission.Continue Reading