Traditionally, the various types of plough body have been classified as general purpose, semi-digger and digger (see plate 18). Many variations in mould-board design have evolved over the years but they still basically conform to the original plough body classification.
General purposeThis is a low draft body with a gently curved mouldboard which turns a furrow three parts wide by two parts deep, e.g. 300 mm wide by 200 mm deep. It is useful for grassland ploughing and sets up the land for weathering by winter frosts, which reduces the time taken to prepare a seedbed for spring sown crops.
Semi-diggerThis has a shorter than the general-purpose mouldboard with a more abrupt curve. It turns an almost square sectioned furrow and leaves a more broken surface finish. Semi-digger bodies can be used at different depths and speeds, making them suitable for most of the general plough iron the farm.
DiggerThis body has a short, abruptly curved mouldboard which can turn a furrow deeper than its width. It has a higher power requirement and leaves a very broken surface. Digger ploughs are mainly used for land to or planted with potatoes and other root crops. Being intermediate between the two moldboards above described, it has a performance that comes in between (approximately 250 mm deep) and with less shattering than the digger moldboard.
Plate 18. Types of plough body. From the top: general purpose with a sword share, semi-digger, digger and slatted mouldboard.
Slatted mouldboardsare preferred by some farmers. They consist of a number of curve steel slats bolted to the frog. They tend to break up the soil more than a full mouldboard and improve soil movement across the mouldboard when working in sticky soils.
Continental design mouldboardsare similar in shape to those used on semi-digger bodies but they can be used for a wider range of working depths and ploughing speeds. This type mouldboard is used on many of the ploughs made by British and continental manufactures and has replaced the more traditional types plough body on most farms.
Plate 19. The underside of a bar point body.
Bar pointA special share with an extendable bar, often spring loaded, which is moved forward as the point wears away, can be used with some types of plough body. The bar point share is ideal for rocky soil conditions where boulder occur close to the surface. The spring loaded bar recoils when it strikes an obstruction below the and then returns to the working position again. Ordinary shares would be damaged in such conditions, and although the bar point leaves a rather untidy furrow bottom, it saves of frequent share replacement.
Plate 20. This semi-mounted plough, made in 5- to 10-furrow versions, is suitable for crawlers or large wheeled tractors running on the land. It has a mechanical variable furrow width adjustment from 300-450 mm in 25 mm steps.
Variable furrow width ploughs.Many ploughs have a fixed furrow width, usually 300, 350 or 400 mm. The will be set at one of these widths but it altered with a toolkit; this is a lengthy task and is rarely done in practice. However, there are times when it would be an advantage to alter furrow width. For example, in good conditions the tractor may have enough power to turn wider furrows, thus increasing the work rate. Alterations to furrow width may also be desirable when there is a need to change ploughing depth, improve burial of trash or drive at higher speed to increase the soil crumbling effect of the mouldboards.
Plate 21. Furrow width on this plough can be varied on the move with a hydraulic ram. A memory unit closes the plough down to its narrowest furrow width before it is rotated by the reversing ram. This is done to prevent the bodies striking the ground when they are reversed before starting back into work. When ploughing re-starts, the bodies are automatically returned to the pre-set furrow width
The width of all the furrows can be adjusted on some ploughs, either with a turnbuckle arrangement or a hydraulic ram. Both methods provide a rapid way of moving the plough bodies on the frame with a parallel linkage mechanism to the new setting. The range of furrow widths achieved varies from 300-500 mm, depending on the model of plough.