A Simplified Approach towards Draft Control in Hydraulic Machines for Component/Cost Reduction

Draft Control is a mechanism in tractors to maintain the penetration of its rear attachment (plough) in ground to avoid engine overload and keep the operation under control. The concept was introduced in excavators for controlling the cutting edge penetration of the bucket in the ground. The idea is to implement draft control automation in excavators without involving complex or expensive electronic sensors and ECUs. The proposition is to use an adjustable pressure relief valve to sense the pressure acting in the cylinder. The relief valve acts as pilot control valve to control the Boom input, thus maintaining the digging depth of the excavator bucket. The relief valve adjustment allows the user to control the bucket through different terrains, i.e., hard debris, soft soil, dust, etc. thus allowing the engine and pump to run under control conditions at all times. The potential expands to the optimizing operational efficiency with minimalistic addition of components. The paper includes detailed concept and MATLAB model to validate the system.