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Disc coulters should be set just deep enough to cut a clean furrow wall. If they are too deep they will ride the plough out of work and cause excessive wear to the coulter bearings. They should also be set so there is little clearance between their cut and the landside of the shin. Under normal conditions set the disc with its centre above the point of the share and allow a clearance of from one inch to one and a half inches between disc and point. Laterally it should be half an inch away from the landside of the share when parallel to the beams. I n hard or stony land it should be set farther back and raised slightly. Most disc coulters can be tilted to or from the land, or in other words given overcut and undercut. A slight amount of undercut (top edge of disc away from land) is often an advantage when ploughing grassland. Coulters should not be tilted unless the work is improved thereby, as the tilting causes increased wear on the coulter bearings and shins. To get the best results, the correct setting will only be found by trial and error, using these notes as a guide.
AVOID THESE FAULTS - ( I l l
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b.
There are two types of skim coulter in general use, namely the independent skim attached directly to the beam of the plough and the skim attachment which forms part of the disc assembly. Most ploughs can be fitted with either and the choice will largely depend upon the conditions under which the plough is working. In a general way it will be found that independent skims work more satisfactorily where loose combined straw, excessive top vegetation or manure have to be ploughed in. The setting of each type is similar and in most cases they should be set just deep enough to ensure that all rubbish is buried. X common fault is setting the skim coulters too deeply. Care should be taken to see that the skim does no more than pare off a sufficient band of soil to achieve this object. The skim should also be set sufficiently forward to enable skimming to fall to the furrow bottom before the furrow begins to move across the face of the mouldboard. If placed too far back the skim will break the furrow up as it is turning and so leave ragged work. When ploughing in an excessive amount of trash it is often advisable to increase the natural clearance of the plough by moving the skims farther back. The skim point should be set as close to the discs as possible without actually touching and should not be set at too abrupt an angle.
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Disc is set too far to the left and gives a stepped furrow wall
P
Disc is set too far to the right and increases draught