Concept of slippage permissibility and the damage during the operation tillage

The objective of this article review is to highlight and discuss the allowance or permissibility and damages of the tractor wheel slippage in previous study of field operation tillage in different soil texture and various condition such as tractor speed, tillage depth, soil moisture and tire inflation …ect . One of the most important indicators that must be taken in to account in tractors when pulling agricultural machinery is a slippage. Despite the slight differences in the definition of slippage, but they agree on one concept which is: reducing of movement that has certain permissible limits that may not be exceeded maximum permissible 15 %. Slippage occurs when tire friction with soil and the tires rotate with velocity greater than tractor speed. Moreover, this causes severe damages (especially if slippage exceeds 15 %) for the tire and soil, compact soil, forms a hard pan, destroy soil structure and fertility, waste time and power, more fuel consumption and tire wear. There should be a reasonable and simple percentage of slippage in order to absorb shocks or impacts and maintain the means of transmission in the tractor during the start of the tractor's movement or during the penetration of the plows into the soil, especially at great depths and in hard or clay soil. Many studies have concluded that the best slippage is 8-12 %. Zero tractor tire slip is impossible in operation tillage (this only happens on the road). Most factors affected in the slippage such as speed, depth, weight and type of the tractor, tire condition (pressure, size and tread life), soil condition (moisture, soil type and residue), implements and type of field operation.