PISTON 3678584 - Caterpillar

Illustration 1 g00285114
Schematic of engine speed sensor
(1) Magnetic lines of force
(2) Wire coils
(3) Gap
(4) Pole piece
(5) Flywheel ring gear The engine speed sensor is a permanent magnet generator. This engine speed sensor has a single pole. The engine speed sensor is made of wire coils (2). The wire coils go around a permanent magnet pole piece (4).As the teeth of flywheel ring gear (5) cut through magnetic lines of force (1) that are generated by the permanent magnet, an AC voltage is generated in wire coils (2). The frequency of this voltage is directly proportional to engine speed.Refer to the Operation and Maintenance Manual, SEBU6711, "Speed Sensor - Clean/Inspect" for the adjustment of the engine speed sensor.Refer to Troubleshooting, SENR6413 for troubleshooting the engine speed sensor.