1
Fig 12
Basic Calibration Procedure (Continued)
Sowing Small Seeds
Calibration with Disconnected Agitator Shaft
The fine seed metering wheel used in Duncan Drills is especially well suited for sowing small seeds such as rape. Due to the intensive action caused by the agitator the seeds can adhere to each other, or be damaged, causing irregular sowing/germination.
Therefore it is recommended that when sowing small seeds, especially oil seeds and thin shelled seeds, the drive to the agitator is disconnected. To do this remove the lynch pin (1) (Fig 12).
Deviations between the calibrated and actual seed rate can occur when residual dressing agent sticks to the bottom flaps and thus slows the flow of seed. Before beginning the actual calibration test fill the calibration trays by turning the crank handle at a high speed around the 90 setting on the gearbox scale. This will cause an immediate buildup of the dresssing agent on the flaps. Return the contents of the calibration trays to the seed box and proceed with the actual calibration. Due to the residue buildup on the flaps your calibration will now reflect accurately the required seed rate.
It is advisable with small seeds to use the 1/20 hectare method for your calibration, thus cutting down on weighing errors.
Note: Remember to reconnect the agitator shaft as required for other seeds, otherwise the consistency of seed rate will be affected.
Caution: When resetting the metering wheels on the seeder shaft
Care should be taken when tightening the grub screws on the fine seed wheel (Page 20, Fig 10/3). Adjust the grubscrew until the movement of the metering wheel just stops, then tighten no more than 1/8 of a turn.
Do not overtighten as this can result in breakages while operating and may render the warranty on these units void.
Pt. No. 67372 Issue 0806
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