RETAINER-VALVE SPRING 2N9297 - Caterpillar

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Typical metal particle detector
Some engines have a metal particle detector. The detector is an electrical sensor that detects 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 circuit Engine oil is continuously circulated through the detector. The 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.The metal particle detector has an input to the Programmable Logic Controller (PLC). The input will generate either an engine warning or an engine shutdown. The response depends on the length of time and/or the amount of metal particles that are detected.