A torque evaluation for a rotary subsoiler

There are many models describing the work of rotary tillers, including torque evaluation. However, the work of a rotary subsoiler is different from that of a rotary tiller, which cuts the soil into pieces and throws them behind the machine. The rotary subsoiler acts on the soil with pressure similar to passive narrow tines. However, the existing models of forces acting on passive implements refer only to their linear movement. In this paper, a hypothesis has been made that the methods used in predicting the forces on soil cutting narrow tines may be applied to a rotary subsoiler, taking into consideration the subsequent positions of the working element in soil and including some corrections connected to the rotary movement of such a tine. On this basis a new mathematical model for predicting torque for a rotary subsoiler in different soils has been developed. Because no theoretical models describing the work of rotary subsoilers can be found, the prediction of the torque requirement may be very important for designers, as well as for other experts applying such machines in the field operations. After development the model was verified in experiments performed in a soil bin, which proved the model to be reliable. (C) 2005 Elsevier B.V. All rights reserved.