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buletinul institutului politehnic din iaşi - Universitatea Tehnică ...

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Bul. Inst. Polit. Iaşi, t. LVIII (LXII), f. 4, 2012 261<br />

By analysing the experimental results it was found that an increased soil<br />

penetration resistance is lea<strong>din</strong>g to a slightly increased driving wheel travelling<br />

speed; this is explained by the fact that for more compact soil the driving<br />

wheel-soil adhesion increases, causing the decrease of wheel slip and therefore<br />

increasing the carriage travelling speed. It was also concluded that an increased<br />

soil resistance to penetration increases the traction force developed by the<br />

driving wheel, as a result of the wheel–soil adhesion increase.<br />

Regar<strong>din</strong>g the influence of the driving wheel vertical load over the soil, it<br />

was established that the rise of this force leads to an increased travelling speed<br />

of the driving wheel, and, therefore, of the carriage, due to the increase of<br />

wheel- soil adhesion, that makes its slippage to diminish.<br />

In all cases, driving wheel slip had values that fell within the limits laid<br />

down by agro-technical requirements; these requirements provide that on<br />

compacted soil driving wheels slip should not exceed a maximum of 20 %.<br />

4. Conclusions<br />

1. The laboratory test rig with soil channel, aiming to study the wheelground<br />

interaction, is a very important achievement, absolutely necessary in the<br />

experimental researches carried out in laboratory conditions regar<strong>din</strong>g this<br />

interaction. This laboratory test rig was constructed as a result of the PNCDI II-<br />

52107 research grant.<br />

2. Experimental research carried out with plough body shows that the<br />

increase of plough body travelling speed leads to a increase of the towing<br />

resistance force and of the specific power consumption (a significant increase<br />

of specific power consumption). It may also be noted that an increased soil<br />

penetration resistance leads to a notable increase of towing resistance force and<br />

of the specific power consumption.<br />

3. It must be emphasized that as the body plough working depth<br />

increases, there is a increase of the towing resistance force.Regar<strong>din</strong>g the<br />

specific power consumption, it was concluded that: increasing the working<br />

depth from 100 mm to 150 mm leads to a slight decrease of the specific power<br />

consumption and by increasing the working depth from 150 mm to 200 mm it is<br />

found a significant increase of the specific power consumption. These<br />

variations may be thus explained: the working depth increase leads to a increase<br />

of specific power consumption for rolling over and breaking down the<br />

displaced slice of soil.<br />

4. Based on the experimental results, it was established that the increase<br />

of the driving wheel rotational speed leads to a increase of its travelling speed<br />

and traction force and a a decrease of the wheel slip. It was also established that<br />

an increased soil penetration resistance resulted in increased driving wheel<br />

speed and traction force, while its slip decreased.

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