AFR200 Series, Product User Guide
This document is subject to change without notice.
Caution: None of GAC products are flight certified controls including this item
Copyright © 2010, Governors America Corp., All Rights Reserved
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PUG4144 D
7 Engine Sensor Information & Installation
7.1 Magnetic Engine Speed Pickup
The Magnetic Speed Sensor detects when ring gear teeth, or other ferrous projections, pass the tip of the sensor.
The output signal is an AC sine wave whose frequency is converted to crankshaft revolutions per minute (RPM)
via the input flywheel teeth value within the AFR.
For information on selecting and adjusting the magnetic pickup see: GAC Document:
PTI3000, Magnetic Speed
Sensors
which can be found at the following location:
•
http://www.governors-america.com/magnetic_speed_sensors.html
GAC offers various lengths, electrical connections, and both US and metric threads for the speed sensors. The
following is a picture of a typical variable reluctance magnetic engine speed pickup offered by GAC.
Magnetic Speed Pickup
7.1.1 Application Considerations
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Some industrial engines have pre existing threaded holes for speed pickup installation. If this is the case
determine the appropriate thread (dimension, US or metric) and length sensor required.
•
If there is no pre-drilled hole exists, then drilling and tapping a hole or fabricating a bracket to position
the magnetic pickup over the flywheel teeth may be necessary.
•
The threaded hole for the speed sensor should be perpendicular to the centerline of the crankshaft and
centered over the ring gear teeth.
•
The magnetic pickup should be mounted parallel to the flywheel clutch surface and normal to the
crankshaft axis of rotation.
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Any ferrous gear can be used as long as the frequency and amplitude of the resulting signal meet the
speed control specifications.
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The wire leads should be twisted the entire length (14 turns per foot) and may also require shielding if the
run is longer than 10 ft. [3 m] or if external interference is present.
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The shield should never be connected to either of the leads from the speed sensor. They are
typically connected to a large ground point near the controller-end only (e.g. engine block).
7.1.2 Installation Instructions
1. Ensure the engine is not running and the ignition switch is turned to the OFF position.
2. Install the magnetic pickup in the engine bell housing, ring gear case, or fabricated bracket.
3. Screw the speed sensor in until it touches a gear tooth and then back it out 3/4 of a turn.
