Grain And Plenum Temperature Sensor Locations; Scr Drive And Meter Roll Information; Meter Roll Blockage - Farm Fans C-2120A Operator's Manual

GRAIN AND PLENUM TEMPERATURE
SENSOR LOCATIONS
The following sensor location diagram is provided for
servicing convenience.
REAR END LOOKING
INTO PLENUM DOORS
Fig. 7-9 Grain and plenum temperature sen-
sors
SCR DRIVE AND METER ROLL
INFORMATION
SCR DRIVE — GENERAL INFO.
The meter rolls (which regulate the rate of grain flow
through the dryer) are driven by a separate DC type
electric motor. The DC motor speed is variable and is
controlled by an electronic SCR type (silicon controlled
rectifier) control located within the ASC control box.
See Table 1-3 for SCR system specifications.
The main SCR components are the SCR control board
assembly, DC motor, and speed reducer gear box.
These parts are briefly described as follows:
1. SCR SPEED CONTROL — The Manual Control Dial
on the ASC control panel regulates the SCR control
board, to control the speed of the DC motor which
drives the meter rolls.
2. DC ELECTRIC MOTOR — The 3/4 HP direct current
(DC) motor provides the drive for the meter rolls and is
located on the rear left-hand side of the Dryer (except
on special front discharge models). The motor powers
the gearbox through a V-belt drive arrangement. The
V-belt drive provides protection from possible severe
damage to the meter rolls and other components, in the
event the meter rolls ever become jammed with any
large foreign object.
GRAIN HI-LIMIT
THERMOSTAT
RTD PLENUM
SENSOR
PLENUM
HI-LIMIT
THERMOSTAT
GRAIN HI-LIMIT
RTD GRAIN
SENSOR
PLENUM
HI-LIMIT
THERMOSTAT
RTD PLENUM
SENSOR
49
The DC motor requires no operational adjustments and
is completely controlled by the SCR control board
assembly.
3. SPEED REDUCER GEARBOX — The 50:1 gearbox
provides the required speed reduction and transmits
power to the meter rolls through a drive chain arrange-
ment.
The gearbox requires no adjustment and under normal
conditions is considered lifetime lubricated.
C-2140A models only: The gearbox is initially filled
with a Union Carbide synthetic lubricant which has an
operating temperature range of minus 40°F to 250°F.
If after prolonged usage the unit requires additional
lubricant (due to leaks or repair), drain and flush with
solvent. Then refill unit with 1.05 pts. of FF part no.
069-1132-5 oil (Mobil SHC634 or equivalent lubricant).
C-2120A, C-2125A, & C-2130A models only:
Although the gearbox requires no adjustment, it is ini-
tially filled with an AGMA #8 mineral-base oil which
should be replaced after the first 250 hours of opera-
tion, then changed every drying season (or 2500 hrs.)
thereafter. AGMA #8 oil has an operating temperature
range of 51° to 110°F. For cold ambient temperatures
(16° to 50°F), use AGMA #7 rated oil.
requires additional lubricant due to leakage or repairs,
be advised that Farm Fans offers a highly durable, syn-
thetic oil, FF part no. 069-1132-5 (Mobil SHC634 or
equivalent lubricant). Fill to oil level plug (near shaft
level). Before changing to synthetic oil, first drain and
flush with solvent. Synthetic oil allows for wider tem-
perature operation (minus 40° to 250°F typical) and
longer lifetime use (5000 hours operation typical).
The drive chain should be periodically lubricated and
the drive belt and drive chain should be checked and
retensioned as required.

METER ROLL BLOCKAGE

In the event a foreign object becomes lodged in the
meter rolls and jams the system, the following events
could be expected to occur.
A. The unloading auger and the SCR meter roll drive
would briefly continue to operate.
B. However, the moment the meter roll becomes jammed,
the self-limiting SCR drive motor will stop rotating (and
SCR drive belt may begin slipping) and the meter rolls
would not rotate.
HOW TO DETERMINE METERING PROBLEM
To determine if a metering problem is caused by block-
age of the meter rolls, remove the drive covers from
front and rear ends of dryer and perform the following:
Refering to Fig. 6-14, remove meter roll drive chain
from the meter roll sprocket. Using a pipe wrench,
rotate the hub of the drive-side meter roll sprocket back
and forth. Apply up to 100 ft.-lbs. of force to attempt to
free any lodged object. If both metering rolls will turn, it
can be assumed that no blockage exists and that the
If the unit