PLATE-DRIVE 4L8854 - Caterpillar

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(2) Case drain filter for the center and right implement pumps
(3) Case drain filter for the engine cooling fan pump and motor
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Left side of the machine
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(4) Case drain filter for the steering and brake pumps
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Case drain filter
(5) Filter bypass switch
(6) Filter housing
(7) Oil inlet passage
(8) Oil outlet passage
(9) Filter elementThe case drain filters remove any debris that is in the hydraulic oil. The case drain filters also prevent contamination between the various systems. Contaminated oil is prevented from returning to the hydraulic oil tank.During normal operation, the oil flows through the oil inlet passage (7) to the oil outlet passage (8).Correct maintenance recommendations must be followed in order to ensure that the filter does not become plugged with debris. If the filter is plugged, the flow of filtered oil to the system stops. However, unfiltered oil will flow past the bypass valve which is located inside the filter housing (6). This oil will then flow to the hydraulic oil tank. When the oil does not flow through the filter element, the debris in the oil could cause damage to other components in the hydraulic system.The filter bypass switch (5) is monitored by the implement ECM. When the filter element is plugged oil pressure on inlet side of the filter housing (6) increases. This pressure causes the filter bypass switch (5) to move to the OPEN position.The implement ECM will display a Warning Category 2. A Warning Category 2 indicates that the filter has been plugged for more than 30 seconds. The operator needs to notify the shop.Note: The oil will also bypass the filter element during cold start-up conditions when the oil is below 52 °C (125 °F). In this case, the VIMS will not display a warning. As the oil warms up, the bypass valve will move to the CLOSED position. This action will allow the oil to flow through the filter element unless the filter element is plugged.High Pressure Screens
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Inside of the rear loader frame on right side of machine
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(10) Implement pump
(11) Implement pump
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Left side of machine near transmission oil filler tube
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(12) Screen for the brake pump
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Access door behind the cab
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(13) Steering pump screen
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Rear of machine
(14) Screen for the fan motor
(15) Screen for the fan pump
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High-pressure screen
(17) Oil inlet passage
(18) Oil outlet passage
(19) Screen housing
(20) Drain plug
(21) ScreenThe screen (21) inside the high-pressure screen housing (19) removes any debris that is in the hydraulic oil.During normal operation, the oil flows through screen housing (19) to oil outlet passage (18).Correct maintenance recommendations must be followed in order to ensure that the high-pressure screens do not become plugged with debris. If the high-pressure screens become plugged, the flow of oil to the high-pressure system stops. The oil will not bypass the screen if the screen assembly is plugged.