Design, Development and evaluation of Electronic control valve for hydraulic pump of MF 285 Tractor

The depth control systems used in Iranian tractors are mechanical and they produce variable tillage depth in uneven field surface. In this research a rotary type electronic control valve was designed and constructed. By using this valve, electro-hydraulic tillage depth control system was developed and installed on the tractor. The control system was composed of: a depth sensor, a Programmable Logic Controller (PLC), a stepper motor with deriver, a control valve and a Programmable Terminal (control panel). In this system, the tillage depth was measured by utilizing a depth sensor and the control valve which is controlled by the stepper motor was used to 3-point linkage control. The laboratory results showed that the depth variations were controlled well by the developed system within ±2 cm in the steady state. Also the field data indicated that the mean tillage depth of electro-hydraulic depth control system was greater than that of the mechanical depth control system with significance difference.