Calculation of plough draught resistance and energy consumption factors during ploughing

Calculation of Tractive Resistance and Energy Consumption Factors

Tractive resistance is a key indicator that determines the choice of tractor and operating gear for a ploughing unit. It consists of the useful resistance, necessary for soil deformation and furrow slice turnover, and harmful resistance. Harmful resistance includes energy costs for rolling the plough itself, friction of jointers and plough bodies against furrow walls, as well as friction in wheel bearings.

Harmful resistance (P₁) is proportional to the mass of the plough and is calculated by the formula: P₁ = 9,8 f m, where m is the mass of the plough, and f is the soil resistance coefficient. Useful resistance consists of two parts: the force of soil deformation (P₂) and the force of soil throw (P₃). Soil deformation is calculated as P₂ = K₁ a b n, where a is the depth of ploughing, b is the working width of one body, n is the number of bodies. The soil throw force depends on the square of the unit's speed and is calculated by the formula P₃ = ε a b n v², where ε is the coefficient of the plough body working surface shape and soil properties, and v is the speed of movement.

• Resistance coefficient for stubble (f) — 0,5
• Soil deformation resistance (K₁) — 20–50 kN/m²

The total tractive resistance of the plough is calculated using the rational draft force formula: P = 9,8 f m + K₁ a b n + ε a b n v². For practical field unit assembly, a simplified calculation using the average specific soil resistance (K_с) is often used: P = K_с a b n. The obtained value allows for precise selection of the tractor model and optimal gear for specific operating conditions.

How to Bring Actual Productivity Closer to Theoretical

Theoretical productivity of a ploughing unit shows the maximum work output during time T under ideal conditions. It is calculated by the formula W = 0,1 B v T, where B is the design working width of the plough, and v is the calculated speed of movement. In practice, the actual output (W_ф) is always lower than the calculated one due to tractor slippage, time losses during turning and maintenance, as well as deviations from the working width.

To evaluate actual performance, a correction factor K is used: W_ф = 0,1 B v T K, where K = B_р v_р T_р / B v T. The index "р" here denotes the actual operating parameters: real working width, speed, and net working time in the field. This coefficient shows how effectively the equipment's potential is utilized in a specific field.

1. Control the working width. Properly adjust the working parts and the tractor's hitch, avoid overlaps during passes, and monitor the technical condition of the plough.
2. Minimize slippage. Maintain the tractor in optimal technical condition so that the actual speed does not drop relative to the theoretical one.
3. Reduce downtime. Optimize shift time: minimize time spent on turns, travel, cleaning of working parts, and machine refueling.
4. Switch to a multi-shift mode. During peak periods, organize two- or three-shift operation of ploughing units.
5. Implement the group work method. Operating ploughs in teams simplifies their technical maintenance and reduces unproductive time losses.