Wheel Loaders VS Crawler tractors
With the widespread popularity of wheel tractors, crawler tractors are becoming more and more strange compared with many users. But in the actual field operation, the return of crawler machinery has gradually revealed the signs, which is more due to the irreplaceable advantages of crawler tractor compared with wheel tractor.
1. Traction and traction efficiency
The crawler tractor has higher adhesion and greater traction force than wheel tractor. Under the same machine weight, the traction force of crawler tractor is 1.4-1.8 times of that of wheel tractor. The actual test shows that the c1402 track tractor with 140 horsepower is 1.3 times of 180 horsepower 1804 wheel tractor (of which 1804 machine weight is 400 kg heavier than 1402).
In terms of traction efficiency, the maximum traction efficiency of wheel tractor is 55-65% in theory, and that of crawler tractor can reach 70-80%. That is to say, for tractors with the same horsepower, the effective power of the wheel tractor engine is 15% more than that of the tractor. The results show that the tractor traction efficiency of crawler tractor is about 10-20% higher than that of four wheel drive wheel tractor on hard ground and cultivated land. Generally speaking, 85 or 90 horsepower shoe tractor can be used as wheel tractor with more than 100 horsepower.
2. Specific pressure of grounding, adhesion and influence on soil structure
The ground of the crawler tractor is lower than the pressure. The specific pressure of the ground of each type of crawler tractor from 51.5kw to 132kw is 44.7-53kpa, while the specific pressure of the wheel tractor with the same power level is much higher, which results in poor tire adhesion and high slip rate. Take 95.6kw tractor as an example: the specific pressure of grounding of Dongfang red c1302 crawler tractor (with bulldozer) is 47.7kpa, while that of wheel tractor of the same horsepower section is about 104kpa, which is more than twice of that of crawler tractor. Through the test, when the high-power wheel tractor and the five share plough are working together, the slip rate is generally 10-20% and some of them reach 25% when the average soil moisture content is 30%, the solid degree is 0.3MPa and the unit speed is about 7.2km/h.
The wheel tractor has a large grounding pressure. When plowing, the rear wheels always walk in the ploughing ditch. The cutting effect of tires on soil causes the soil structure of the ploughing layer to be destroyed. After several years of cultivation, hard bottom layer will be formed under the soil layer, which is not conducive to the soil water conservation and crop growth. Even after deep rake, the small and small hard blocks will be kept and the microstructure of soil is destroyed. In addition, the investigation of farming in the central Henan and Northwest China shows that the deep groove of the rear wheel rolling caused the inconsistency between the sowing depth and the soil cover, which brought extremely adverse effect on the sowing quality and also brought difficulties to the subsequent watering operation.
The results show that the seedling emergence rate of cultivated land is only 30% - 40% after being compacted by wheel dragging, while the seedling emergence rate can still reach 80% - 90% after the compaction. The ratio of the earth to the track is lower, the compaction degree of the soil is smaller than that of the wheel tractor, and the effect of deep ploughing is especially prominent, which makes the crawler tractor have obvious advantages in low and wetland operation. For example, some regular large farms have clear requirements, and wheel dragging is prohibited when the moisture content is more than 50mm.