My state has lots of clay, that is the only reason I know anything about plows, and it’s not much. Of course we had steel by that time.

The first part is an asymmetric plough share, which cuts the soil horizontally. The second part
is a coulter, which cuts the soil vertically. The third part is a mouldboard, which turns the cut
sods aside to create a deep furrow (Mokyr 1990; Richerson 2001). The mouldboard is the part
of the heavy plough from which its principal advantages on clay soils derive. The first
advantage is that it turns the soil, which allows for both better weed control on clay soil in
damp climates and incorporation of crop residues, green manure, animal manure, or other
substances into the soil (Richerson 2001; Guul-Simonsen et al. 2002). The second advantage
is that mouldboard ploughing produces high-backed ridges, which contributes to more
efficient drainage of clay soils. The ridges also allow for better harvests in both wet and dry
seasons. The third advantage is that the heavy plough handles the soil with such violence that cross-ploughing is not needed, thus freeing up labor time. Hence, by allowing for better field drainage, access to the most fertile soils, and saving of peasant labor time, the heavy plough
stimulated food production and, as a consequence, “population growth, specialization of
function, urbanization, and the growth of leisure” (White 1962, p. 44).
http://www.ehes.org/EHES_70.pdf

Pictures:
https://sites.google.com/a/brvgs.k12.va.us/wh-15-sem-1-medieval-europe-gm/the-heavy-plow

@KNOWITALL!!

@Dutchess Weird right? I’ve always found farm machinery cool, I’m odd. And my friend is a very well paid soil analyst.

Impressive and illuminating lesson.

@KNOWITALL….every year we have an a steam engine show at the fairgrounds. It’s mostly antique farm machinery.
C’mon down! I’ll buy you lunch. You like Happy Meals? ;]

@KNOWITALL , I appreciate what you have done, but I am still having trouble visualizing. When they say that the ploughshare cuts the soil horizontally, does that just mean that it widens the cut made by the coulter? How does the mouldboard turn the soil?

@LostInParadise So I posted on FB and a friend is sending me pics of a few. When I get them I can email to you. I specifically requested the oldest 3 part plows for ya. :)

The reason heavy ploughs are called heavy ploughs is because they are heavier than a basic mould-board plough replacing quite fragile wooden components with cast iron or steal meaning thay were capable of ploughing heavier soil.