SEAL-LIP TYPE 1505841 - Caterpillar

Metal Particle Detectors
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Front view and left side view of the metal particle detectorsThe engine has two metal particle detectors. The detectors are electrical sensors that detect the presence of metal particles in the engine oil.Metal particles from worn components such as bearings, piston rings, and gears can be suspended in the engine oil. Detection of the particles will activate an alarm or a shutdown in order to alert the operator of the condition. Corrective maintenance that may prevent more costly repairs can then be performed. For example, replacement of a main bearing may prevent the need to replace a crankshaft.
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Schematic of the electrical grids (A) Open circuit (B) Closed circuitThe two metal particle detectors are parallel in the flow of engine oil. Engine oil is continuously circulated through the detectors. Each detector contains a perforated board with tin plated electrical grids. The grids are an open circuit. The engine oil flows between the grids. If a metal particle closes the gap between the grids, the circuit is closed.Each detector has an input to the programmable logic controller. If either one of the detectors senses metal particles, an alarm is generated. If both of the detectors sense metal particles, a shutdown is generated.Oil Mist Detector
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Oil mist detectorThe oil mist detector helps protect the engine against serious damage that can originate from the overheating of bearings and/or piston components.The oil mist detector uses a vacuum and individual pipes that draw the atmosphere from each compartment. If the oil mist exceeds the threshold, the alarm relay is activated. The detector then determines the source of the oil mist. Valves for all of the pipes are sequentially opened and closed in order to sample the atmosphere from each compartment. Groups of compartments are compared. The compartment with the alarm is indicated on the face of the detector.For detailed information on the detector, refer to Service Manual, RENR2225, "Oil Mist Detectors".Resistance Temperature Detectors (RTD)
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Resistance temperature detector (1) Connector (2) Thermowell (3) ElementAn RTD is a sensor that is used to measure temperature. The electrical resistance of the sensor is a function of temperature.Thermowell (2) is inserted into a liquid or gaseous fluid. A known current is supplied to element (3). The voltage drop across the element is measured. The temperature of the element has a linear effect on the element's resistance. As the temperature increases, the resistance and the voltage drop increase. As the temperature decreases, the resistance and the voltage drop decrease. The voltage drop is interpreted as a temperature.
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Electrical schematic of an RTD (1) Return terminal (2) Supply terminal (3) Sense terminalIn addition to the current supply and return wires, a third wire is used. The resistance of a sensor with two wires can be calculated but the three wires enable the monitoring system to calculate the element's resistance with more accuracy. The element's resistance is calculated from the equation in Table 1.
Table 1
    V (3) - V (1)     =
    R (4)