This model is of a four-furrow, 'Suncog' stump-jump disc plough. It was made in Australia by H.V. McKay Pty Ltd of Sunshine, Victoria. Full-size Suncog stump-jump ploughs were an Australian innovation made by this famous Australian agricultural manufacturing company at Sunshine from 1913 . The discs on the plough slope backwards so that they entered the ground with an undercut. In the Mallee areas of NSW and Victoria this type of plough was popular for ploughing virgin land. It was also effective for summer fallow dealing with weeds, paddymelon and stinkwort.
Stump-jump disc ploughs were largely the invention of James B. Garde, (who was manager of the Tillage Department of McKay's Sunshine Harvester Works at Sunshine, Victoria, Australia) and C.A. Peacock (a Victorian ploughmaker), just after the turn of the century. Garde applied the stump-jump principle to the disc plough soon after its arrival in Australia, taking advantage of the rolling action which reduced the friction of the mouldboard and shares. The stump-jump disc plough enabled the arid scrub country to be cultivated. Its heavy frame bore down on the scrub and the discs sliced through the roots and bushes burying some of the undergrowth but leaving most of it on the surface so it could be collected. These ploughs usually consisted of concave steel discs mounted on an independently sprung member so that when a disc met a root too thick or too hard to cut through it rode over it and was immediately pulled back down again by a strong spring. The discs were set at an angle both to the ground and the furrow-wall. This allowed them to have a scooping action and while they did not make a deep or well turned furrow they were certainly very useful in cultivating new land. The size of stump jump disc ploughs ranged from two-furrow to nine-furrow models and they were so well suited to Australian farming conditions that they became the most widely used primary cultivation implement.