Ground Drive
– Metering Drive System
Page 62
05/06
Checking the Variator for Damage
It must be remembered that the variators,
even
though
they
are
of
robust
construction, have a limited torque capacity.
Care must be taken when operating the
metering system to avoid overloading the
metershaft.
DO NOT
leave fertilizer in the bin for
extended periods of time.
DO NOT
use wet or damp fertilizer.
DO NOT
use a ‘High Rates’ sprocket ratio
if not recommended.
ALWAYS
check that the metershaft turns
freely by using the handle supplied (fig.
MD3) before calibrating or engaging the
clutch.
Fig. MD3 Checking Metershaft.
CHECK THAT THE METERING SHAFTS TURN
FREELY.
This operation should become standard
procedure after travelling any length of time
which would allow the fertilizer to compact,
or if material has been left in the bins
overnight.
If you feel the variator is damaged in any
way
you should consult your local
authorised service centre.
One method used to check your variator is
to place material in the bin and set the
variable adjustment at the maximum setting
(10). Fit the calibration collection box and
turn the calibration handle to operate the
variator.
The variator output shaft, when set at
maximum, should rotate 1 turn for every 4
turns of the input shaft. You will need to
mark the shaft or sprocket and have
someone watch the input shaft side while the
person
turning
the
calibration
handle
watches the output side.
Drive System
The variators are driven by the ground
wheel, through a series of sprockets, and an
electro-magnetic clutch.
The clutch is operated from the cab of the
tractor via the clutch switch. It can be
engaged or disengaged at anytime when at
seeding
speeds
or
while
stationary.
ALWAYS
check that the metershafts turn
freely before engaging.
Disengaging sprockets are fitted to the
drive shafts before the variators. These
large sprockets have a drive pin that can be
disengaged to isolate a meterbox for
calibration or seeding purposes.
The 3 bin model seeders often have a
second clutch to isolate one of the bins that
can be operated from the tractor cabin.
Checking the Drive System
To check the resistance of the drive
system, fit the calibration handle and hang a
spring scale from the handle. With the clutch
disengaged and both metering systems
operating, but both bins empty, rotate the
handle pulling through some spring scales.
Resistance should not be greater than 11kg
at the handle.
Check bearings and all moving parts for
damage if resistance is high.
Lubricate all bearings and chains.
Replace sprockets and chain if badly worn.
