الفهرس 
Tractor performance under trailed loadsOnly 14 pages are availabe for public view
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Abstract
Farm tractors play a main role in providing the powers to execute the most important agricultural operations such as tillage, planting, irrigation, threshing and transport.. .etc. Efficient power performance includes the selection of implements that neither overload nor partial load to use adequately the power available from a tractor. Trailed and mounted loads might consume almost all tractors’ available power in Egypt. At full throttle, good fuel economy and good power utilization result from loading the engine to 80 % or more of maximum engine power (James and Bloome, 1996). Some of agricultural operations consume less of 80 % of power. However, the proper selection of power and implement lead to partial load specially the number of tractors about 89068 according to statistics of 1996 (AAS) in Egypt. However, this numbers of tractors consumes as much as 890680 ton of Diesel fuel per year approximately, when the average power reached 44.12 kW. The main objectives of the present study was to study the tractor performance under trailed and mounted loads on various traction surfaces, estimate the usable power from the tractor and determine the proper selection between farm power and implement by using the developed equations. To achieve these objectives, two parts of field experiments were carried out Faculty of Agriculture, Kafr El-Sheikh Governorate. The first art of experiments: The variables of the first part of experiment were as follows: 1- Three different traction surfaces: (plowed, firm and paved surface). 2- Three different applied weights: (9.81, 14.72 and 19.62 kN). 3- Four different forward speeds, the values of forward speeds was ranged between minimum and maximum value as follows: (1.600- 1.980), (2.673- 3.207), (5.593-6.83 1) and (7.500-12.237) krnlh. 4- Two drives mode of tractor, 2WD (Two-wheel drive) and 4WD (Four-wheel drive). The main results can be summarized as follows: -Actual forward speed: The forward speed decreased with increasing trailed loads on all traction surfaces. The forward speed decreased fi-om 1.569 to 1.493 kmlh by using the 2WD and from 1.492 to 1.412 kmlh by using the 4WD when the trailed load increased from 9.81 to 19.62 kN. It was found that, the forward speed was decreased from 1.98 to 1.88 to 1.6 on paved, firm, and plowed surface by using the same gear and fuel consumption rate, respectively. -Drawbar null: The drawbar pull increased by increasing theoretical forward speed for all traction surfaces. The trailed load needed more of drawbar pull in case of 2WD comparing with 4WD at the same theoretical forward speed.