A Method for Energy Efficiency Rating of Low-Power Tractors Based also on Intensity of Use

The efficiency of the so-called “low-power” tractors is affected not only by the evolution of their engine and transmission design, but also by the usage modes adopted. Especially in specialized crops, such as vineyards and orchards, many tasks do not require high engine power and/or traction pull, being the power of the tractor used by the hydraulic system. A customizable method to analyze and evaluate the real efficiency of narrow tractors (N-TRE) have been developed in 2019, taking into account some tractor models working in different scenarios. These scenarios have been characterized in given working activity and usage intensity, along the growing season. The working conditions and the power requirement of the main operations carried out in viticulture were simulated in a stationary mode by means of an electromagnetic dynamometer, integrated with devices for measuring the fuel consumption. The basic output has been a series of engine performance curves (power, torque and Specific Fuel Consumption, SFC), both at full and partial loads. On these curves, some characteristic working points were identified, simulating the typical tractor running conditions in vineyard. The aim of this study is to validate the N-TRE model by testing its robustness with a given number of tractors, to build a suitable database. The database will be finalized to classify the machines in some efficiency classes, identified with letters from A to G, similarly to what happens for example in several electric and electronic household appliances. Furthermore, the classes A to G were associated to a colour tag, adopting the traffic light criterion (green/yellow/red). These codes could immediately and easily show the tractor global efficiency in different working scenarios, to offer at a glance to farmers a comprehensive machine evaluation.