Influence of plant oil use for fuel supply and hydraulic systems of tractor engine

Abstract

Plant oils were tested instead of the mineral ones to minimize the quantity of the imported oils and nature pollution. The oils for hydraulic systems were produced from Žet-net variety rape seeds by cold pressing with the screw press. The rapeseed oil was thermally processed (in the temperature reaching 260±5 ºC, processing duration – 1 hour) and catalysts were added – 25 % of cupric oxide. The rapeseed oil was stabilized by adding local plant admixtures. The viscosity of rapeseed oil used in hydraulic systems of agricultural machinery was 0.917 g·cm-3, the relative viscosity at 50 °C was 3.3 Er, the alkaline number was 0.6 mg KOH·g-1, and the quantity of sulphur was 0.002 %. The test duration was 180 hours. The oil characteristics during the test practically remained unchanged, the hydraulic system maintained stability and worked without jerking. No oil foaming was noticed. The pressure in the hydraulic system during the tests was 12.0-12.8 MPa, oil temperature at the nominal loading did not exceed 43 ºC. The influence of rapeseed and linseed oil on high pressure hoses and polyethylene tubes used in the hydraulic system in relation to oil temperature was tested. This test lasted for 3500 hours. The largest change in the diameter of the rubber hoses was noticed when they were kept in rapeseed oil at the temperature of 75 ºC – it amounted to 18.6 % (in linseed oil – 11.8 %), the surface hardness decreased by 36.4 % (in linseed oil – 44.6 %). Neither kind of oil, nor the temperature had any influence on the PVC tubes.