Cat Digital Ignition System (CDIS)
The digital ignition system includes a timing disc, a speed sensor (timing), a timing control, and wiring harnesses.
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| Illustration 1 | g00771229 |
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Timing control | |
The timing control has an "APPLICATION" switch and a "TIMING" switch. The "APPLICATION" switch is set to correspond with the engine model and a range of desired ignition timing. The "TIMING" switch is used to fine tune the desired timing.
The digital ignition system uses a capacitor which stores voltage for the ignition. The timing control has a relay switch which releases the voltage to the ignition transformers.
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| Illustration 2 | g00771249 |
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Cross section of the front housing for the timing disc (1) Timing disc (2) Speed sensor (timing) (3) Gear | |
Timing disc (1) is installed with gear (3) that is driven by the camshaft gear. The driven gear rotates at one-half of the engine speed. Sensor (2) monitors the rotation of the timing disc in order to sense a reference position of the crankshaft.
The timing disc has seven magnets. Six of the magnets represent the six cylinders. Each magnet that passes the sensor causes the sensor to send a signal to the timing control. The timing control initiates the ignition by releasing voltage from the capacitor to the transformer of the proper cylinder. When the seventh magnet passes, the sensor indicates that another revolution of the crankshaft will begin.
There are two options for providing the electrical power for the timing control:
- The customer provides a source of 12 VDC or 24 VDC.
- An alternator enables self-powered ignition.
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| Illustration 3 | g00771260 |
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Alternator for the digital ignition system | |
The optional alternator is installed onto the magneto drive. A wiring harness connects the alternator to a voltage regulator in order to provide the correct voltage to the digital ignition system. Voltage for the timing control is regulated to 27 ± 3 VDC.