Studies on a Three-point Linkage Dynamometer for Mounted Implements (II)

Abstract

1) Since three-point linkage dynamometer reported in the previous paper had a mechanical failure between each pin dynamometer and three-point link, its improvements shown in Fig. 1 was made.
2) As the results of their improvements, each pin dynamometer measured loads above 300kg with an accuracy of within ±3%, while prior to improvements it messured above 500kg with an accuracy of within ±5%.
3) Calibration curve and measuring accuracies were investigated by applying static load on three-point linkage dynamometer, using calibrating apparatus and methods shown in Fig. 2, 3.
4) The results are approximately summarized by the statement that the dynamometer, limited to tractor using a free linkage, will measure loads above 300kg with accuracy of within ±3%.
5) The investigation of three-point linkage dynamometer compared with the trace tractor method of draught measurement was carried out.
6) On the concrete test track condition, the draught obtained by using a strain gage dynamometer minus that by the three-point linkage dynamometer was approximately equal to the rolling resistance of the tractor. The effect of towing speed and draught was not recognized.
7) In relation among the draught of the three-point linkage dynamometer L₂, and top link horizontal force T, and lower link horigontol force supperposed L+R, the ratio T/L₂ and L+R/L₂ were 6% lower than, and very similar to, the results obtained from the graphical analysis (Fig. 12)
8) On firm loam and sandy loam soil test track condition, draught of the implement obtained were from 200 for 1150kg, by changing the depth of heavy duty cultivator. As the results, draught force L₁ (trace tractor method) and L₂ (three point linkage dynamometer) were neary equal. (Fig. 14) The effect of towing speed and draught was not recognized.