MacDon FD75 OM - Manual (Page 151)

OPERATION
In addition to the power (A) and ground (B) wires, a signal
wire (C) is connected internally to a movable wiper that
sweeps the high resistance filament band. This wiper is
attached to an external arm. As the external arm is rotated
and the wiper is moved toward or further away from the
power wire connection, the measure of resistance at the
signal wire (C) changes.
The resistance measured across the signal and ground
wires should show a uniform progressive increase from
a low (80–100 ohms) to a high (800–1200 ohms). This
can be observed if an ohmmeter is connected across
the signal and power wires and the sensor shaft rotated.
When an input voltage is applied to the high resistance
filament band through the power wire (A) the output (or
“measured”) voltage in the signal wire (C) is changed by
this variable resistance
NOTE:
Ground and power wires may differ depending
on combine.
Figure 4.198: Power, Ground, and Signal Wires
4.7.3 Header Float
Float reduces the header weight and allows it to more easily follow the ground and quickly respond to sudden
ground contour changes or obstacles.
Header float is indicated on the CA25 float indicator (A) and
the values 0 to 4 represent the force of the cutterbar on the
ground, with ‘0’ being the least and ‘4’ the maximum.
The maximum force is determined by the tension on the
adapter float springs which are adjustable. The tension
is factory set but can be changed to suit field and crop
conditions. Refer to
Checking and Adjusting Header Float,
page 138
The FD75 FlexDraper
®
combine header performs best
with minimum ground pressure, under normal conditions.
Re-adjust the float if adding optional attachments that
affect the weight of the wings.
Figure 4.199: Float Indicator
169894 137 Revision A