11
Installation
(cont.)
Magnets
Please read the following information about magnet
spacing and polarity.
The number of magnets that must be used depends on the
size of your tire and where you mount the sensor. On trac-
tor or implement wheels the general rule of thumb is one
magnet for each wheel bolt
(minimum of two, and always
an even number)
. For drive shafts or small wheels (ATV’s),
two magnets are usually adequate.
Some installations may require that more than two magnets
be installed. To determine the number of magnets required,
measure the distance traveled of one revolution of the sen-
sor equipped wheel in inches (centimeters).
See the following tables to find the minimum number of
magnets required (always an even number)
The magnets provided by Micro-Trak are marked with a
punched dashed line on the SOUTH pole side of the magnet.
See Illustration 4.
Always use an even number of magnets, and always alter-
nate the polarities of the magnets as you go around the
wheel hub or drive shaft.
To install, mount the first magnet with the SOUTH pole side
(dashed line) facing toward the hub or shaft. Mount the
second magnet with the NORTH pole side facing toward the
hub or shaft.
See Illustration 5.
For proper operation, the magnets must be evenly spaced
around the wheel or drive shaft. The magnets must be at
least 1" apart.
See Illustration 6.
NOTE: Magnets may be attached mechanically or adhered
with epoxy or other high quality adhesive. When using
adhesive, thoroughly clean the area of dirt and oil
.
S
N
Illustration 4
North
North
North
South
South
South
1
2
4
3
5
6
Test magnet
should alternately
attract and repel.
Illustration 5
1” Minimum
Illustration 6
English or Turf (inches)
Wheel Circumference
40
80
120 160 200
Number of Magnets
2
4
6
8
10
Metric (cm)
Wheel Circumference
100 200 300 400 500
Number of Magnets
2
4
6
8
10
Magnetic Speed Sensor Installation
Please Note: If you have purchased an Astro GPS speed
sensor or a Vansco radar or other speed sensing device,
disregard the section on magnetic speed sensors and in-
stall the optional speed sensor as described in the instruc-
tion packed with the unit.
Locations where the magnetic sensor may be installed:
1. Non-driven wheel on tractor, vehicle or implement. This
is less susceptible to errors resulting from wheel slip.
2. Tractor, vehicle or planter drive shaft. This type of
mounting is recommended for trucks, four-wheel drive
tractors or other equipment that has poor or no access
to a non-driven wheel.
Hall-effect Speed/Flow Sensor
Cable - P/N 13096
15’ 3-pin M/P 150 Extension
Cable - P/N 13207
14” Nylon Cable ties (10)
P/N 12910
Magnets (6)
P/N 12069
(2 in Hardware
Bag)
Hardware
Bag
P/N 13251
Speed Sensor
Mounting
Bracket
P/N 10013
