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| Illustration 1 | g01902733 |
(1) Final drive oil filter | |
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| Illustration 2 | g01902735 |
Final drive oil filter (1) (2) Filter bypass switch (3) Tap for the Scheduled Oil Sampling (4) Diverter valve (5) Oil pressure switch | |
Final drive oil filter (1) is mounted on the left side on the back of the rear axle housing. Oil from the front section of the rear axle cooling pump flows to diverter valve (4). The oil then flows to final drive oil filter (1). From final drive oil filter (1), oil flows to the final drives that are on both sides of the truck. Oil also flows to the wheel bearings on both sides of the truck. The diverter valve (4) is controlled by the Brake/Cooling ECM.
Filter bypass switch (2) is located on the filter housing. The bypass switch provides an input signal to the Brake/Cooling ECM. The Brake/Cooling ECM sends a signal to the VIMS, which informs the operator if the differential oil pressure is low.
If the filter element plugs, the unfiltered oil is bypassed back to the axle housing (sump) rather than being bypassed in-line. This could allow contaminated oil to flow through the wheel bearings. The final drives can operate for an extended period of time with the filter in a bypass mode. The primary source of lubrication for the final drives is by the splash lubrication.
Oil pressure switch (5) is located on the filter housing. The pressure switch also provides an input signal to the Brake/Cooling ECM. The Brake/Cooling ECM sends a signal to the VIMS. The VIMS will then inform the operator if the oil pressure for the final drive is low.
Oil samples can be taken at the Scheduled Oil Sampling tap (3).
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| Illustration 3 | g01902753 |
Section view of the final drive oil filter (6) Housing (7) Element (8) Inlet passage (9) Bypass spool (10) Bypass passage (11) Spring (12) Outlet passage | |
Oil from the inlet line flows into inlet passage (8). This oil fills the space that is between element (7) and the inside of housing (6). During normal operation, the oil flows through element (7). The oil then flows through outlet passage (12). Element (7) stops any debris that is in the oil.
If the filter element becomes full of debris, the restriction to the flow of oil causes a pressure increase inside the filter. If the pressure of the oil achieves the bypass pressure, the pressure oil causes bypass spool (9) to move against the force of spring (11). The oil then goes through the open bypass spool (9). This oil flows through bypass passage (10) to the rear axle housing and the bypass line to the rear axle housing (sump). Filter bypass switch (2) notifies the VIMS of this occurrence. When the oil does not go through the filter element, the debris that is in the oil may cause damage to the other components in the system.
Correct maintenance must be used to ensure that element (7) does not become full of debris and that the flow of clean oil is not stopped.