sharebeam

The sharebeam is a heavy beam, typically made of cast iron or ductile iron, that forms the primary structural member of a plough to which the share (the actual cutting blade) is bolted or riveted. It runs horizontally beneath the plough body and carries the full cutting forces generated as the share penetrates soil. In moldboard ploughs, the sharebeam extends forward from the main frame and supports both the share itself and the point (the reinforced tip that bears the heaviest wear).

The sharebeam's geometry determines plough performance. Its depth below the frame controls how far the share cuts into the soil, typically between 50 and 100 millimetres depending on soil type and implement class. The angle at which it is set influences the soil's resistance to cutting. Cast iron sharebeams are favored for their ability to withstand the brittle fracture that would occur in softer steel when the plough strikes a stone or subsoil impediment; the iron simply breaks at the fracture point rather than bending permanently out of alignment.

Shares are replaceable, and the design of the sharebeam determines which share profiles will fit. A typical moldboard plough might use shares ranging from 350 to 500 millimetres in width, with the beam width sized accordingly. The mounting surfaces must be precisely machined to ensure the share sits at the correct angle and does not rock or deflect sideways under load.

The sharebeam is the wearing component that absorbs both abrasion from soil minerals and shock loads. After extended use, the share becomes dull and the sharebeam itself may develop cracks radiating from bolt holes or the point where it joins the main beam. Maintenance involves regular sharpening of the share and inspection for metal fatigue. Replacement sharebeams are a standard spare part stocked by agricultural dealers.

In reversible (two-way) ploughs, dual sharebeams are mounted to turn soil to either side. In walking ploughs, the single sharebeam is integrated into a simpler frame that the operator guides by hand. The term sharebeam distinguishes this component from the landside (which runs along the unploughed soil) and the frog (which is the frame block that typically holds the blade assembly in place on modern implements).