Magnetic Speed Sensor Installation - micro-trak Calc-An-Acre II Reference Manual

Installation
(cont)

Magnetic Speed Sensor Installation

Magnet Locations
1. Non-driven wheel on tractor, vehicle or implement - 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 limited access to a non-driven wheel.
Number of Magnets
The number of magnets that must be used depends on the size of
your tire and where you mount the sensor. On tractor 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 sensor equipped
wheel in inches (meters). Divide that measurement by 20 for English
and Turf units, or by .5 for Metric units, and then round up to the
nearest even number (always use an even number of magnets). That
number will be the minimum number of magnets required for the
installation.
Example in English/Turf units: If your revolution measurement is
97 inches, dividing that number by 20 gives you a value of 4.85.
Rounding 4.85 up to the nearest even number is 6. For this example,
the minimum number of magnets required is 6.
Example in Metric units: If your revolution measurement is 2.5
meters, dividing that number by .5 gives you a value of 5. Rounding
5 up to the nearest even number is 6. For this example, the minimum
number of magnets required is 6.
The magnets provided by Micro-Trak® are marked with a punched
dashed line on the SOUTH pole side of the magnet.
Always use an even number of magnets, and always alternate 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.
For proper operation, the magnets must be evenly spaced around
the wheel or drive shaft. The magnets must be at least 1" apart.
Attaching Magnets
The magnets are attached to a wheel hub or drive shaft and the
speed sensor is mounted directly over the magnet. When the wheel
or drive shaft begins turning, a speed impulse is sent to the Calc-
An-Acre II console every time a magnet passes by the tip of the
speed sensor. For the speed sensor to operate properly, the spacing
between the magnets and the tip of the sensor must always remain
constant. Before permanently mounting any parts, be sure that the
location you have selected will meet the following requirements.
NOTE: Magnets must alternate in polarity.
Locate the Following Parts
• Speed Sensor Cable (Green Body)
• Mounting "L" Bracket
• Magnets
• Cable Ties
South
North
Magnet Polarity
North
5
South
North
Magnet Layout
Magnet Spacing
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.
Mounting Detail
10
Test magnet
should alternately
South
attract and repel.
1
6
North
2
3
4
South
1" Minimum
Sensor assembly must not
be mounted more than
45° from perpendicular
Bracket must
45° max
3/8" nuts
Sensor
(Green body)
¼" to ½" air gap
Magnet
be rigidly
mounted