If a transmission part is to be repaired, make sure only good repairs are made. Makeshift or temporary repairs should not be permitted, except in an emergency. The principal purpose of repairs is to salvage components that would otherwise be scrapped. The decision as to whether apart is to be repaired rests upon three factors; First, the practicality of the repair, (That is, will the repair of the part return it to a near new condition?); second, the cost of the repair job as compared to the cost of a replacement; and third, the availability of the replacement part. If replacement parts are unavailable or in short supply, make every effort to salvage as many parts as possible.
Small holes or cracks in the transmission case, shifter shaft housing, or clutch housing maybe repaired by welding or brazing, provided they do not extend into the bearing bores or mounting surfaces. These pieces are gray (cast) iron, and special techniques are required to weld these materials satisfactorily; normally, ordinary welding methods and materials are not suitable.
To assemble a transmission, use a reverse procedure from that of disassembly. Check the manufacturer's manual for proper clearances and the wear limits of the parts.
All parts, whether new or used, should be lightly coated with lubricating oil. This is done immediately after inspection or repair. Oiling the parts gives them a necessary rust-preventative coating and facilitates the assembly operations.
Train your personnel to have all the necessary parts on hand before the assembly operation begins. This guarantees that the transmission can be completely assembled without interruptions.
As a CM1, it will be your responsibility to test the transmission after it is assembled. If all parts are correctly assembled, the transmission gears will all rotate freely without evidence of binding. Use a suitable wrench to rotate the input shaft at least ten full revolutions. Shift the transmission into all the speed ranges. If the transmission is noisy, extremely loose, or binds, it must be disassembled and further corrective measures taken.
Transfer cases (fig. 11-9) are placed in the power trains of vehicles to allow them to operate in mud, snow, sand, and other unusual terrains. To do this, you have to have driving power available at the front wheels as well as the rear wheels so the vehicle will not get stuck. Therefore, certain wheeled vehicles include a second gearbox, called the transfer case. Its purpose is to take the output power from the transmission and divide it so
Figure 11-9. - Example of a transfer case assembly (5-ton truck, military).Continue Reading