The document provides information on adjustments and operation of a power thresher. It discusses: 1. Adjusting the clearance between the cylinder and concave to properly thresh grains while minimizing cracking. The clearance is narrowed from the mouth to rear end. 2. Setting the cylinder speed based on manufacturer recommendations, typically between 1520-1830 rpm for wheat and 370-920 rpm for rice. 3. Adjusting the fan to provide sufficient blast to remove chaff without losing grains, monitored by inspecting sample output.

1. 14. POWER THRESHER
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5. THROW IN TYPE FEEDING UNIT

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23. ANGLED BAR TYPE CYLINDER
•Cylinder is equipped with angle iron bars, helically fitted on the cylinder
• the sheped bars have rubber pads on their faces
• the clearance between cylinder and concave unit at the entrance is from 13
mm to 19 mm and reduces to 6 to 9 mm only

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41. THRESHER ADJUSTMENTS: The following adjustments can be done on a stationary power
thresher:
Cylinder and concave clearance:
• In order to get cleaned grains and proper threshing, it is very important to set the proper clearance between tip of
cylinder and concave. On an average, concave clearance is kept about 25 mm at the mouth, 10 mm at the middle and
15 mm at the rear end.
•Start operating the thresher, by keeping proper recommended speed, and check if any grain is left in the ears. If it is
so, reduce the concave clearance gradually, until drum is threshing cleanly. Too close concave setting is likely to
crack some of the grains.

42. Cylinder speed:
• The drum of the thresher should be rotated at proper speed for better threshing and cleaning efficiency.
Normally, manufacturers specify the cylinder speed for different crops.
• The cylinder speed can be checked using tachometer.
• Operator should check the speed occasionally under load for proper functioning of thresher.
• The cylinder peripheral speed for wheat is kept between 1520 to 1830 rpm and for paddy between 370
to 920 rpm.
Fan adjustment:
• Fan(s) fitted on thresher must provide the proper amount of blast. The shutter(s) at
each end of fan should be adjusted properly so that it could provide blast sufficient
enough to remove chaff and light materials without grain. Watching the sample and
adjusting the blast can help in getting the desired results.
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49. PRECAUTIONS AND CARE IN OPERATION OF THRESHER
• 1. The machine should be installed at a leveled surface as far as possible.
• 2. The direction of the machine should be set inconsonance with the direction of the prevailing wind.
• 3. The machine should be fixed in the ground with the help of suitable pegs or by digging into the ground.
• 4. The thresher should be operated at the speed recommended by the manufacturer.
• 5. Suitable size of pulley should be should be provided on the thresher to operate the cylinder at recommended
speed.
• 6. The feeding should be continuous and uniform.
7. Bearings and other working parts should always be properly greased and oiled.
8. Before starting the machine, the main pulley should be driven by hand to ensure that
there is no obstruction inside the machine.
9. While feeding, care is to be taken that crop should be free from any wooden or iron
pieces.
10. It is desirable to dry the crops before feeding, as far as possible.
10. The sieves should be inspected frequently and cleaned from time to time to avoid
clogging.
11. While feeding, the operator should not insert his hand deep in the feeding trough.
12. After continuous working for 8 to 10 hours, the machine should be given some rest
before it is put into operation again.
13. After threshing season, all the belts should be removed and the machine should be kept
in a covered place.

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57. PREVENTIVE MAINTENANCE
• Before operating the machine, all bolts and screws should be checked for tightness.
• Bearing caps should be removed and bearings filled with grease gun after every 20
hours of operation. Wood and metal carriers for the straw rack, sieve and grain pan
and crank shaft connecting rod bearings, should be oiled with waste oil.
• Foreign matter (if any) in the crop should be removed.
• Threads on the concave adjustment and bolts should be oiled or greased occasionally.
• Damaged and bent parts to be checked and repaired.
• Sieves to be checked and cleaned if necessary.

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