Author(s)

MARCO BIETRESATO & FABRIZIO MAZZETTO

Abstract

Using agricultural machines on slopes is very risky for operators: drivers difficultly have a correct perception of the stability condition of their vehicles when travelling, especially because it is impossible to instantly check the ground elevation and harshness in correspondence of each wheel. Moreover, the tests that are usually performed to characterize these machines’ stability are scarcely helpful in real conditions: these tests check the lateral overturning (maximum angle) in two static configurations only. Evidently, these do not cover most of real situations, do not locate its centre-of-mass and do not consider the centrifugal force (causing load-transfers and dynamically-variable readjustments of the machine’s trim in turnings), thus making impossible the setup of eventual active/passive safety-systems to be installed on vehicles.

Therefore, with the aim of overcoming the limitations of actual tests, giving a higher level of information to the tractors’ manufacturers and users, we have conceived a completely-new test-apparatus to be installed within our laboratory: the Tiltable Platform. It integrates two subsystems, illustrated hereinafter.

(1)  The tiltable/angleable plane is a wide flat structure (15×15 m), able to simulate different ground- gradients, allowing a vehicle to manoeuvre/travel on it along circular paths in a controlled and safe environment. It can also generate an angle at half of its width, transversal to the maximum-slope direction (simulating the exits of an agricultural machine from the inter-rows).

(2)  The tilting turntable: has a circular shape and is divided into quadrants, each capable of measuring the weight sustained due to a motionless vehicle positioned on them; it is installed on a tilting structure and can rotate around a vertical axis, thus allowing to vary the angular position of the vehicle’s longitudinal axis with reference to the maximum-slope direction.

Finally, this test-rig will be useful to develop new test-methodologies to certify the agricultural machines’ stability in real operating-conditions (e.g. operating with ballast/mounted-implements). 

Keywords

stability of agricultural machines on slopes, static tests of stability, dynamic tests of stability, innovative test-equipment, tiltable/angleable plane, tilting turntable.