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Section 3 - Operation
Ballasting
Measuring Wheel Slip
One of the functions of the Tractor Performance Monitor
is to measure wheel slip automatically and inform the
operator if the wheel slip is at an unacceptable level
based on a pre-programmed value set by the operator.
For more information on the wheel slip feature, see
“Tractor Performance Monitor” earlier in this section.
If the tractor does not have the optional Tractor
Performance Monitor, wheel slip can be measured as
follows:
1. Put a reference mark on the side of the tractor rear
tire.
2. Operate the tractor with the implement in the
ground.
3. While the tractor is moving, have an assistant put
a marker on the ground outside the implement
width where the reference mark on the tire comes
down to the ground.
DANGER: MAKE SURE THE ASSISTANT IS CLEAR OF
THE IMPLEMENT AND TRACTOR DURING WHEEL
SLIP MEASUREMENTS.
4. Continue to move along with the tractor and
count ten wheel revolutions. Put a second marker
on the ground outside the implement width where
the reference mark on the tire comes down to the
ground for the tenth time.
5. Lift the implement out of the ground. Put the
tractor in position next to the first ground marker
and put a new reference mark on the rear tire to
aligned with it.
6. Operate the tractor, with the implement raised, from
the first ground marker to the second ground marker.
Count the number of wheel revolutions between
the two ground markers.
7. The tire will require fewer revolutions to cover the
same distance because of less slip. The following
table will determine the percent of wheel slip from
the number of wheel revolutions:
When you have too much ballast installed on the
tractor, you will see the clear shape of the tire bar
in the ground which is an indication of no slippage.
With too little ballast, the tire barmarks will not show
because of the tire slippage.
Too Little Ballast
1. Excessive wheel spin
2. Power loss
3. Tire wear
4. Excessive fuel consumption
5. Lower productivity
Too Much Ballast
1. Increased drivetrain load and power operating cost
2. Power loss
3. Tire strain
4. Soil compaction
5. Lower productivity, i.e., more power required
to move the overloaded tractor, allowing less power
available to pull the implement.
Rolling Resistance
The greatest loss of engine power occurs in the area
of traction factors such as rolling resistance and wheel
slippage. Those losses will occur in any and every
practical traction situation.
Therefore, choosing the right amount of weight is
the first step. Too little weight permits excessive
wheel slippage while too much weight increases soil
compaction and rolling resistance. Rolling resistance
is the power required to roll the tractor’s tires forward
with no load except weight.
Revolutions of Wheel Slip %
9-1/2
5
9 10
8-1/2 15
8 20
7-1/2
25
7 30