مرکز منطقه ای اطلاع رساني علوم و فناوري - ساخت و ارزيابي دستگاه كامل اندازه گيري و مطالعه فرآيند زمين و گيرايي تحت شرايط كنترل شده

چكيده لاتين :

Increasing traction force and efficiency of farm tractors result in more crop productivity and saving of energy consumption. Optimizing these parameters requires detail study of effective condition on performance of traction wheels. In this research development and evaluation of a compelet laboratory system capable of testing and measuring performance parameters of small traction wheels were envisaged.The aparatus consisted of a soil bin having a dimension of 6, 0.3 and 0.3 meters for its length, width and depth respectively. The soil bin transverse on a 12 meter length rail by its antifriction wheels has neglegible moving resistance. Inside the bin different texture could be processed to a desired condition by using tillage and compacting implement that were fixed on stationary frame, and water mister was used to control the humidity of the soil. The driving system consists of an electric motor, a three speed gear box and a traction wheel jointed by suitable levers and free pivots to a stationary frame which provides aparatus movement and exerts different normal loads by using various weights. Data measuring system consisted of two strain gage load cells, one located between the wheel and stationary frame which measure gross traction effort and the other located between the soil bin and adjustable braking system that measures net traction or pull. Two D.C. generators were used for measuring the speeds of the wheel and soil bin separately. The output singnals of the measuring transducers are electrical potential difference which are analog signal and converted to digital signal by a 8 bits and 4 channels data logger. The signals are then transferred to a computer for processing and displaying the quantity of forces, speeds and slippage. A cone penetrometer determines the.cone index for every soil condition from surface to 0.15 meter depth. During different traction tests, other soil parameters such as texture, structure, water content and machine parameters such as diameter and width of the traction wheel, normal load and slippage could be measured. By obtaining these parameters and substituting them by different traction models, calculated traction performance quatities that are comperable to measured quantities in various conditions can he achieved. Also traction performance of the small or model traction wheels can he studied and evaluated by changing each ofʹ the effective parameters in the tests. The aparatus showed good accuracy when some traction performance tests were performed.