Brandt GRAIN VAC 5000, Operator And Parts Manual

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44
5.13 Air Throttle Function
The grain vac has a unique feature. The air throttle serves two functions. First it limits the high horsepower
consumption of a centrifugal type blower operating at very high airflows and it eliminates grain loss through
the fan of the Grain Vac.
The throttle operates in the following manner: The throttle plate is a circular plate positioned in the air
discharge duct on the discharge side of the fan. The plate is spring loaded in the open position. As the
airflow reaches a certain velocity, the air turns the plate to choke itself off and extends the spring. As soon
as the airflow returns to normal, the spring pulls the throttle back to the open position to allow full suction
at the hoses.
The air throttle is a very important feature of the grain vac. If it is not operating properly, a variety of
malfunctions could be encountered. If the plate is stuck in the closed position, capacity will be poor. If the
plate is stuck in the open position, you will encounter high power consumption and product discharged
from the fan outlet. Because of the large amount of air flow the fan can produce, excessive strain can be
put onto the slip clutch in the PTO shaft causing it to slip and damage the clutch pack.
To check if the air throttle is working correctly, use the following procedure:
1. Remove the suction inlet plug and fold
the auger into operating position.
2. Engage the PTO on the tractor at an
idle, slowly open the throttle observing
the throttle arm position. As the tractor
approaches full PTO speed, the throttle
control arm must rotate closed 90°
counter clockwise.
3. If the throttle is not opening or closing,
check the assembly for binding.
Loosening the tension spring may also
be required.
4. If you experience the air throttle
fluttering, adjustment should be made.
To correct this problem simply tighten
the adjusting bolt (see Fig. 33) until
the flutter is removed.
5. During operation, the throttle plate
should remain fully closed all the time
that there is no grain being conveyed.
As soon as grain enters the vac system,
the plate should open to the position it
is in when the unit is shut off.
F
IG
. 33 A
DJUSTABLE
A
IR
T
HROTTLE
Adjustment
Bolt
Spring