Dainius Steponavičius, Aurelija Kemzūraitė, Valdas Kiniulis, Albinas Andriušis, Darius Juknevičius


Technological and structural parameters of a threshing unit must ensure the highest possible quality of its operation under minimum input and cost. The aim of the study was to estimate the variation of speed of threshing cylinder with two different shapes of filler plates (FP-I and FP-II) under various corn ear feed rate into combine harvester.
Threshing cylinder speed (frequency of rotation) nb (min-1) was measured simultaneously each 0.075 s using stationary tangential single-cylinder threshing unit located in laboratory-training ground intended for investigation into technological processes of agricultural machinery. Frequency of rotation of non-loaded threshing cylinder speed amounted for 450 min-1.
Increase in corn ear feed rate from 6 kg s-1 to 12 kg s-1 caused frequency of rotation of threshing cylinder to decrease from nb=437.82±0.21 min-1 to nb=420.96±0.50 min-1 (using FP-I). Replacing covered spaces between rasp bars with FP-II had no effect on cylinder speed – it has decreased from 438.06±0.23 min-1 to 421.37±0.32 min-1. Results showed that in case of FP-I, the amplitude of speed Anb has increased from Anb=4.07±0.44 min-1 to Anb=8.60±0.88 min-1, whereas in case of FP-II – from Anb=2.67±0.25 min-1 to Anb=4.52±0.62 min-1 in response to increased feed rate from 4 kg s-1 to 12 kg s-1. This means that using the covers FP-II the threshing apparatus will work more evenly. The average threshing cylinder speed, irrespective of the closure of spaces between rasp bars, was found to decrease by approx. 20 min-1 in result of increase in corn ear feed rate from 4 kg s-1 to 12 kg s-1. When threshing corn ears, irrespective of the shape of filler plates, the acceptable feed rate amounted for 10 kg s-1, as it caused to exceed the permissible limit of 5 % allowed for decrease in cylinder speed (nb=427.5 min-1).

Keywords: concave, corn ear, feed rate, threshing cylinder

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