BELT-SERPENTINE 3748480 - Caterpillar

Illustration 1 g00680833
Illustration 2 g00453414
Components of the high pressure oil filter in the power train (Circuit (A) )The low pressure oil filter has a larger housing. The components are similar. (1) Bypass valve (2) Spring (3) Switch (4) Outlet Passage (5) Inlet Passage (6) Filter element (7) HousingThe low pressure oil filter (Section (B) ) is located in the enclosure on the right side of the operator compartment. The low pressure oil filter is the inside filter of the two filters.During normal operation, oil flows through the filter element, through outlet passage (4), to the priority valve, and to the torque converter. Filter element (6) 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 outside the filter element. The pump pressure oil fills passage (5) and the oil causes bypass valve (1) to move against spring (2) .The oil then flows past the open bypass valve and to the remainder of the hydraulic system. When the oil does not go through the filter element, the debris in the oil will cause damage to other components in the hydraulic system.The high pressure oil filter is the outside filter of the two filters.Pump pressure oil flows into the filter housing through inlet passage (5) and the oil fills the space between housing (7) and filter element (6) .During normal operation, oil flows through the filter element, through outlet passage (4), to the priority valve, to the main relief valve (transmission), and to the brake control valve. Filter element (6) 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 outside the filter element. The pump pressure oil fills passage (5) and the oil causes bypass valve (1) to move against spring (2) .The oil then flows past the open bypass valve and to the remainder of the hydraulic system. When the oil does not go through the filter element, the debris in the oil will cause damage to other components in the hydraulic system.The power train oil filter bypass opens when the pressure on the outside of the filter element is 175 kPa (25 psi) higher than the pressure on the inside of the filter element.Switch (3) is installed in inlet passage (5). Switch (3) is a normally open switch that is held closed by bypass valve (1). When the bypass valve opens, bypass oil flows around the filter element. Switch (3) opens causing the EMS panel fault indicator and fault light to turn on and the fault alarm sounds.If the oil is at operating temperature and the fault occurs, then inspect the filter elements.Note: The warning function is disabled at oil temperatures that are below 52°C (126°F).Maintain filter elements (6) in order to prevent damage to the hydraulic system components from contamination.