جستجوی مقالات مرتبط با کلیدواژه « creep speed » در نشریات گروه « منابع طبیعی »

Some agricultural operations such as transplanting, flamethrower and digging canals need a low tractors speed, while this speed is created by creep gear in new tractors. ITM 285 tractor is a common tractor used in different agricultural operations in Iran and most agricultural activities are done by them. Its use is limited due to inability to establish low speeds for such operations. In this study, a gearbox was selected to be installed on ITM 285 tractors and its performance in terms of speed and maximum drawbar pull was evaluated. The gearbox consists of a hydromotor and a planetary gear. The tractor hydraulic output is connected to hydromotor. By reducing rotational speed in planetary gear, the hydromotor rotation movement is transmitted to PTO shaft. Because PTO shaft is in wheel round position, the shaft moves cause to movement of tractor. Assessments showed that the made power transmission system is able to produce a speed of 0.12 to 0.38 km/h for tractor. In this case, the measured maximum drawbar pull force was 1421.42 N. This power transmission system can be used in operations such as, transplanting, flamethrower, digging canals and vegetables harvesting.

Since suitable speed must be selected for every work especially in agricultural activities, feasibility of achieving different speeds by operator under the intended conditions is one that companies take into consideration. These speeds include: creep speed, slow speed, farm speed and transport speed. This study aimed to redesign the gearbox of ITM285 to produce a gearbox which can provide the operator with creeping speed besides the span of speeds already existed. After necessary calculations, the kinematical diagram was prepared, the ratio and size of gears were figured out, and the loads on the gears were examined. Both theoretical and software methods were used for calculate and analysis, and the required modifications were made in dimensions. The involute spur gear was drawn using Geartrax2008, modeled in Solidworks2008, and the analysis was made using Ansys11.0 and Cosmos2008. The loads on the pins and shafts in different gears were calculated and examined in terms of their strength to stand for bending and torsion stresses. Considering the restrictions on redesigning and applying the maximum possible modifications on the dimensions and technical specifications of gears in ITM285 gearbox, it was shown that only making some modifications in the gearbox is not enough to achieve creep speed. Using the final driver of ITM399 with the reduction ratio of 4.8 was thus suggested so that the forward speed of 1.2 km/h was achieved