抄録
To establish the predicting method of trafficability of the peat paddy field, authors investigated the physical property of soil and running performance of various tractors, namely track type, half track type and two and four wheel drive tractors. The results are as follows;
(1) Bekker's equation that predicts the tractor sinkage by small rectangular plate is inapplicable, because soil is not considered homogeneous up to the depth of loading area of the tractor.
(2) There are high correlations between cone penetrating resistance and sinkage of tractor, and also sinkage of rectangular plate and sinkage of tractor. Hence it is possible to predict the tractor sinkage by cone-penetrometer or soil hardness tester with rectangular plate.
(3) Cone index at the depth of tractor sinkage was similar to vehicle cone index for various type of tractors. Hence it seems possible to predict the trafficability on the peat paddy field by cone index and vehicle cone index.
(4) Tractor sinkage was the function of n th power of travel reduction, and following empirical formulas were obtained.
Track type tractor Zt=5.22 S0.282
Half track type tractor Zt=2.00 S0.598
Two wheel drive tractor Zt=0.653 S0.758
Four wheel drive tractor Zt=1.98 S0.570
where Zt is tractor sinkage in cm and S is travel reduction in per cent.
