Test Rig and Method for Comparative Evaluation of Conventional and Bio-Based Hydraulic Fluids and Lubricants for Agricultural Transmissions

Abstract

The use of lubricants and hydraulic fluids of both mineral and synthetic origin in agricultural processes could have a deep impact on the environment as a result of their possible dispersion in the ground and aquifers. Replacing them with bio-based fluids, developed to provide good tribological properties and high biodegradability, could contribute to reducing their negative effects. The evaluation of the capacity of such innovative fluids to replace the conventional ones is based on work cycles lasting as long as their lifetime, during which their characteristics must prove to be at least equal to those of the fluids they replace. To shorten the evaluation process, CREA (Consiglio per la Ricerca in Agricoltura e l’analisi dell’economia Agraria) developed a fluid test rig (FTR) and related test method, able to apply severe work cycles on small oil volumes, thereby accelerating the aging of the fluid beyond what typically occurs. This paper reports the results of the tests on FTR’s functionality carried out comparing two UTTO (Universal Tractor Transmission Oil) fluids: a widespread conventional fluid and an experimental vegetable-based oil. The FTR will permit, in a relatively short time, the assessment of the most promising formulations to be tested later under real working conditions, e.g., in agricultural tractors, reducing the risk of damage, before their ultimate introduction into the operating reality.

Bench Test of a Hydraulic Biofluid Based on Refined Pomace Oil

“…From this point of view, the method adopted at CREA‐IT is halfway between the vane pump methods and the axial piston pump methods. The 150‐h work cycle adopted in CREA‐IT former tests on hydraulic fluids, [ 38 ] despite the unchanged characteristics of the oil, appears to be significantly more severe than both tests based on the vane pumps. Prolonging the test duration up to 530 h neared its specific hydraulic work to the value provided by the test based on the Denison P46 axial piston pump.…”

“…The tests were conducted using a test rig (TR) designed and built at CREA‐IT for hydrodynamic tests on hydraulic fluids and lubricants for transmissions. [ 37,38 ] The TR ( Figure ) is used to perform short duration, high intensity work cycles based on the same hydraulic and mechanical strains typical, for example, in the normal use of an agricultural tractor. The basic idea is to strongly accelerate the ageing of the tested fluid by applying higher, controlled levels of mechanical, hydraulic, and thermal stresses on a small volume of fluid.…”

“…As to the work cycle duration, if the global energy developed (hydraulic work and thermal energy) is referred to the fluid volume unit (specific energy, “SE”, kWh dm −3 ), it has been assessed that the “ SE ” developed in a 150 h work cycle under the conditions reported in Table 3 would correspond to the average “SE” of a hydraulic system of a medium power tractor with an oil volume of 80–100 dm 3 , referred to 1 year of work. [ 38 ]…”

Innovative Vibrating Hydraulic Dredge for Striped Venus (Chamelea gallina) Fishing

“…However, making these two functions independent could increase the overall work efficiency; moreover, the presence on board of hydraulic fluid presents a risk of pollution arising from oil leakages in the hydraulic systems. This hazard might be reduced using, for example, new fluids based on vegetable oils (or on esters synthesized from vegetable oils) combined with suitable additives, featuring high biodegradability (>90%) [48]. Alternatively, to the hydraulic solution, the dredge oscillation could be generated by a pneumatic system or an electric motor fit for marine application.…”

Bench Testing of Sensors Utilized for In-Line Monitoring of Lubricants and Hydraulic Fluids Properties

“…This work reports the results of a study on five recently developed sensors for oil condition monitoring installed in-line in an experimental test rig for lubricants [28], introducing a possible test method for the evaluation of the accuracy and reliability of these types of sensors. The tests were carried out on seven oils of different origins (one synthetic ester, two bio-based synthetic esters, and four vegetable oils) and technical characteristics (two UTTOs and five hydraulic oils), under controlled working conditions.…”