BEARING 0990279 - Caterpillar

Low Service Brake Oil Pressure
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Location of the brake accumulator oil pressure switches (1) Brake accumulator oil pressure switch - alert indicator (2) Brake accumulator oil pressure switch - brake applicationWhen the engine is started, brake accumulator oil pressure increases. When the oil pressure reaches the actuation pressure for pressure switch (2), the switch will close. The Power Train/Chassis ECM receives this signal and will allow the parking brake to be disengaged.
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Caterpillar Monitoring System display (3) Brake accumulator oil pressure alert indicatorWhen the oil pressure increases to the actuation pressure for pressure switch (1), the pressure switch will close. The Power Train/Chassis ECM receives a signal from the oil pressure switch. The Power Train/Chassis ECM then sends a signal to the Caterpillar Monitoring System over the CAT Data Link. The Caterpillar Monitoring System will then turn off brake accumulator oil pressure alert indicator (3) on the Caterpillar Monitoring System display.If brake accumulator oil pressure decreases to the deactuation pressure for pressure switch (1), the switch will open. The Power Train/Chassis ECM receives this signal and sends it to the Caterpillar Monitoring System. The Caterpillar Monitoring System will activate alert indicator (3) .If machine operation is continued and brake accumulator oil pressure decreases to the deactuation pressure for pressure switch (2), pressure switch (2) will open. The Power Train/Chassis ECM receives this signal and engages the parking brake.Once the parking brake has been engaged, the parking brake will remain engaged until the brake accumulator oil pressure rises above the actuation pressure for pressure switch (2). The operator must then cycle the parking brake switch from the ON position to the OFF position in order to disengage the parking brake.Reference: For further information on the brake accumulator oil pressure switches, refer to Power Train Electronic Control System, Systems Operation, Troubleshooting, Testing and Adjusting, "Switches".Low Transmission Oil Pressure
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(4) Transmission oil pressure sensorTransmission oil pressure sensor (4) is located on the left side of the transmission compartment. The oil pressure sensor senses the oil pressure in the transmission hydraulic system. The oil pressure sensor sends a signal to the Power Train/Chassis ECM.
Illustration 4 g01188903
Caterpillar Monitoring System display (5) Transmission oil pressure alert indicatorDuring normal machine operation, the transmission oil pressure will be 2690 to 3205 kPa (390 to 465 psi). The Power Train/Chassis ECM will sense this pressure through oil pressure sensor (4). If the transmission oil pressure decreases to 1725 kPa (250 psi), the Power Train/Chassis ECM will send a signal over the CAT data link to the Caterpillar Monitoring System. The Caterpillar Monitoring System will then activate transmission oil pressure alert indicator (5) on the Caterpillar Monitoring System display. The alert indicator will remain activated until the pressure rises above 1725 kPa (250 psi).If machine operation is continued and transmission oil pressure decreases below 1585 kPa (230 psi), the Power Train/Chassis ECM will engage the parking brake.Once the parking brake has been engaged, the parking brake will remain engaged until the transmission oil pressure increases above 1725 kPa (250