N-TRE: A model for the evaluation of the narrow tractors real efficiency

The efficiency of the so called “narrow tractors” is affected not only by their engine and transmission design evolution, but also by the usage modes adopted. In fact, especially in vineyards and orchards, many tasks do not require high engine power and traction pull, but only a remarkable oil flow, because many implements are hydraulically driven. The present work is aimed to create a model (also customizable) to evaluate the Narrow Tractor Real Efficiency (N-TRE), taking into account also different scenarios, in terms of time and intensity usage. At a first attempt, the running conditions and the power requirement of the main operations carried out in viticulture were considered on two narrow tractors, simulated in a stationary mode by means of an electromagnetic dynamometer and integrated with a device 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 operating points were identified, simulating the typical tractor running conditions when working in vineyard.