Abstract
A prototype of a new reversible wheeled articulated tractor, specifically designed for extreme-sloped operations, has been tested in some field trials in two different vineyards. The two test sites, both having vineyards trained with the so-called “pergola” system, were chosen thanks to their extreme slopes and very narrow inter-rows, often lower than 1.00 m. The prototype used in these tests has a configuration that is very close to the commercialization: the technical choices involving its global design and several details are substantially consolidated. In particular, it has very compact dimensions (the seat is placed directly over the engine), a tiltable and retractable roll bar, a peculiar central articulation with two rotational degrees-of-freedom (roll, yaw) and a specifically-designed safety device acting on the articulation (this is actually patent pending). This joint gives the vehicle a great manoeuvrability, needed in turning manoeuvres uphill performed at the end of vine rows. Moreover, the same joint allows the tractor overcoming the soil harshness normally present in off-road tracks, for example when the tractor is travelling in a straight direction in the spaces between the rows of a vineyard. After having instrumented the tractor with two inertial sensors and a GNSS device, we were able to measure the angular positions assumed by the two halves of the tractor, calculating their differential inclinations in relation to the position of the tractor on the fields during a simulated spraying operation. By doing so, we were able in particular to verify that no critical conditions occurred and that the chosen positions of the joint’s roll-angle limits were appropriate to let the tractor operate in comfortable but safe conditions for the driver. Working times and the related field performance indexes were then compared with the analogous quantities referred to a powered cultivator.