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| Illustration 1 | g00951478 |
Schematic of rear axle and final drive | |
Schematic
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| Illustration 2 | g00943136 |
Schematic of rear axle and final drive (1) Brake/Cooling ECM (2) Hydraulic tank (3) Gear pump for the motor drive for the rear axle oil pump (4) Gear pump for brake actuation (5) Piston pump for the motor drive for brake cooling (6) Pump drive (7) Solenoid for diverter valve (8) (8) Diverter valve for the final drive oil (9) Solenoid for unloader valve (11) (10) Rear axle oil temperature sensor (11) Unloader valve for the motor drive for rear axle oil gear pump (12) Screens (13) Final drive oil filter (14) Gear motor for the rear axle oil gear pump (15) Gear pump for the lubrication of the final drive (16) Gear pump for the lubrication of the differential (17) Gear pump for the differential sump scavenge (18) Differential oil filter (19) Differential relief valve (20) Orifice (21) Final drive (22) Breather (23) Final drive oil level (24) Level of rear axle oil when temperature is below 60 °C (140 °F). (25) Drain to the differential oil sump (26) Suction for the differential oil sump (27) Drain to the sump for the rear axle (28) Drain to the sump for the rear axle (29) Level of rear axle oil when temperature is above 60 °C (140 °F). (30) Differential and bevel gear (31) Suction for the sump for the rear axle | |
Location of Components
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| Illustration 3 | g00943138 |
(2) Hydraulic tank (3) Gear pump for the motor drive for the rear axle oil pump (4) Gear pump for brake actuation (5) Piston pump for the motor drive for brake cooling (6) Pump drive (11) Unloader valve for the motor drive for rear axle oil gear pump (14) Gear motor for the rear axle oil gear pump (15) Gear pump for the lubrication of the final drive (16) Gear pump for the lubrication of the differential (17) Gear pump for the differential sump scavenge | |
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| Illustration 4 | g00943140 |
(7) Solenoid for diverter valve (8) (8) Diverter valve for the final drive oil (13) Final drive oil filter (14) Gear motor for the rear axle oil gear pump (15) Gear pump for the lubrication of the final drive (16) Gear pump for the lubrication of the differential (17) Gear pump for the differential sump scavenge (18) Differential oil filter (26) Suction for the differential oil sump (31) Suction for the sump for the rear axle | |
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| Illustration 5 | g00943141 |
(7) Solenoid for diverter valve (8) (8) Diverter valve for the final drive oil (12) Screens (14) Gear motor for the rear axle oil gear pump (15) Gear pump for the lubrication of the final drive (16) Gear pump for the lubrication of the differential (17) Gear pump for the differential sump scavenge (18) Differential oil filter | |
The hydraulic system for the rear axle consists of one lubrication oil that flows to the differential and to the rear axle. This oil lubricates the bearings for the differential and bevel gear and the bearings for the rear wheels. This hydraulic system also cools the bearings for the differential and bevel gear and the bearings for the rear wheels. The hydraulic system for the rear axle is independent from the other hydraulic systems on the machine. For the correct oil that should be used in the system, refer to the Operation and Maintenance Manual for your machine.
Flow Of The Lubrication Oil For The Final Drive At Normal Operating Temperature
Normal operating temperature for the rear axle oil is 60 °C (140 °F). The primary lubrication for final drives (21) and for the rear wheel bearings is by splash lubrication. At any instant, half of the components in final drives (21) are rotating under oil level (23). The gears, bearings, and thrust washers receive the required lubrication by rotating through the oil. The final drive components are also lubricated by splash lubrication from the rotating components in the final drive. Secondary lubrication of final drives (21) and of the rear wheel bearings is by pumping oil to the bearings. Gear pump (15) pumps oil from sump (31) for the rear axle through final drive oil filter (13) to the rear wheel bearings. This oil lubricates the rear wheel bearings, and this oil cools the rear wheel bearings. This oil flows from the rear wheel bearings into the final drive compartments. Oil in the final drive compartments returns to sump (31) for the rear axle by gravity. Before the oil in the compartment of the final drives can return to the sump for the rear axle, the oil must flow through the holes in the retainer plates for the rear wheel bearings.
The oil that flows from gear pump (15) must pass through final drive oil filter (13) for the final drive before the oil flows to final drives (21). When the filter becomes plugged, unfiltered oil bypasses the filter. This unfiltered oil is dumped into drain (28) to the sump for the rear axle. This prevents contaminated oil from flowing through the rear wheel bearings and through the final drive components. When the oil bypasses the filter, the bypass switch will be activated. An alarm will be registered in the cab.
Flow Of The Lubrication Oil For The Final Drive When The Rear Axle Oil Temperature Is Below 60 °C (140 °F)
When the rear axle oil temperature is below 60 °C (140 °F), Brake/Cooling ECM (1) activates solenoid (7) for diverter valve (8). When solenoid (7) is activated, oil from gear pump (15) is diverted to drain (25) for differential oil. If the cold oil was pumped to final drives (25), the final drive compartment would fill with oil. When the oil is cold, the oil has a high viscosity. The high viscosity of the oil will cause the oil to flow too slowly out of the final drive compartment. Sump (31) for the rear axle and differential oil sump (26) would run dry. When the oil is diverted to drain (25) for the differential, the oil level for the differential rises to level (24). Diverting the oil has two purposes. First, the final drive compartments will not be overfilled with oil that is cold. Next, the oil in differential oil sump (26) will rise to level (24). This allows the bevel gear to agitate the oil. When the oil is agitated, the oil temperature will rise quickly. Therefore, the oil temperature will be heated to 60 °C (140 °F) quickly. Now, normal filtering and normal circulation of the oil can occur.
Flow Of The Lubrication Oil For The Differential At Normal Operating Temperature
Normal operating temperature for the rear axle oil is 60 °C (140 °F). Primary lubrication of the differential components is by oil flow that is directed to the gears and to the bearings. Oil is pumped from sump (31) for the rear axle by gear pump (16) for differential oil. The oil flows from the gear pump to differential oil filter (18). The oil then flows past differential relief valve (19) to differential and bevel gear (30) .
During normal operation, the oil in the differential oil sump will be at oil level (29). Gear pump (17) pulls oil from the differential oil sump (26) through screen (12). This oil is then dumped into sump (27) for the rear axle. When the differential oil level is at level (29), the components of differential and bevel gear (30) do not dip into the oil. This allows less agitating of the oil to occur, and the oil will remain cooler.
Flow Of The Lubrication Oil For The Differential When The Rear Axle Oil Temperature Is Below -4 °C (25 °F)
When the rear axle oil temperature decreases below -4 °C (25 °F), the oil will have a high viscosity. The high viscosity of the oil will not allow the rear axle oil pump to pump the oil efficiently. When the temperature of the oil is below -4 °C (25 °F), the Brake/Cooling ECM activates solenoid (9) for unloader valve (11). When solenoid (9) is activated, oil from gear pump (3) is diverted back to hydraulic tank (2). Unloader valve (11) allows a small amount of oil to flow in order to slowly operate gear motor (14). This allows some lubrication to occur in addition to splash lubrication.
Flow Of The Lubrication Oil For The Differential When The Rear Axle Oil Temperature Is Between -4 °C (25 °F) and 60 °C (140 °F)
When the rear axle oil temperature reaches -4 °C (25 °F) and the machine is moving, solenoid (9) is deactivated. Gear motor (14) turns the rear axle oil gear pump. However, if the rear axle oil temperature is less than 60 °C (140 °F), the viscosity of the oil will cause differential relief valve (19) to open. This allows oil from gear pump (16) to dump into differential oil sump (25). This allows less oil to flow in order to lubricate the gears and bearings in differential and bevel gear (30). Oil flow from gear pump (15) is diverted to the differential oil sump (26) in order to allow splash lubrication for the differential.