In many parts of the world, the working season of certain operations is severely limited due to winter freeze-up. This is essentially true in such areas as earth moving and trenching. These limitations are due, in part, to the large drawbar forces which act on the cutting machine as it is drawn through the frozen soil. If this drawbar force could be reduced economically, then the working season of these types of operations could conceivably be extended, resulting in increased productivity and profits per year.
One method of reducing this force is to oscillate the cutting tool as it passes through the soil. Indeed, recent studies have shown that drawbar force reductions of up to 80% can be realized using just this technique. Unfortunately, it has also been shown that the overall power requirements also increase, a negative factor when economical matters are being considered. As a result, it is of utmost importance (for practical applications) to determine the conditions under which the power requirements can be minimized. This report considers one such condition, that is, the condition of the soil itself.
Since frozen soils represent a situation under which drawbar forces are the largest, this study examined the power requirements of an oscillating blade as it passes through both frozen and unfrozen soils (latter case for comparative purposes). The power requirements and force reduction were measured experimentally and data presented graphically for discussion. It is concluded that an increase in power efficiency, for the same force reduction, occurs as the soil becomes frozen (or hard packed). This result is of special importance in earth moving, trenching, etc. applications.