Analysis of Tractor Transmission Pm2805

Transactions of the ASAE Vol. 44(4): 751–757 2001 American Society of Agricultural Engineers ISSN 0001–2351 751 ANALYSIS OF TRACTOR TRANSMISSION AND DRIVING AXLE LOADS D. C. Kim, I. H. Ryu, K. U. Kim ABSTRACT . This study was intended to analyze the loads acting on the transmission and driving axle of an agricultural tractor during plowing operations in Korea. Before the load measurements were made, a survey was conducted to investigate the operational characteristics of plowing by tractors in Korea. The transmission load was measured at the input shaft of the gearbox, and the driving axle load was measured at the final drive shaft of the tractor. The load measurements were made at two speed levels and under five field conditions. Two torque transducers were developed for the respective load measurements, as well as other instrumentation necessary to collect the data and store them in a data logger. The time–histories of the measured torque loads were analyzed and transformed into load spectra using rain–flow cycle counting and the Smith–Watson–Topper equation. Comparison of the load spectra was made to investigate their characteristics. Effects on the load spectrum of soil and plowing speed were also investigated. Finally, a load spectrum combining the results of the spectrum analysis was developed and proposed as an input load for estimating the fatigue lives of transmission components for tractors in Korea. Keywords. Tractor transmission, Load sp ectrum. he transmission of an agricultural tractor accounts for 25% to 30% of the tractor’s total cost. Therefore, proper design of the transmissio n is very important. In order to design it properly, a large amount of load data must be collected from actual field operations. Agricultural tractors are used for many kinds of farm operations under various soil and field conditions. However, the major tractor operations are tillage and transport. To account for workloads in the design of tractor transmissions, operational characteristics such as annual work hours, working speeds, gear selection, and load distributions must be analyzed. It is particularly important to know the number of cycles of loads and their magnitudes under all working conditions. The simplest way to analyze a random load–time history is to count how often a defined–magnitude load has occurred. The load spectrum is a result of such counti ng, and it is usually represented as a cumulative frequency distribution of constant–amplitude cyclic loads. The load spectrum is used for the evaluation of fatigue lives as well as for the derivation of a test code to prove the durability of machine components subjected to a variable random load. Very few studies have been reported in the literature on load analysis or load spectra for agricultural tractors. One of Article was submitted for review in March 2000; approved for publication by the Power & Machinery Division of ASAE in March 2001. Authors are Dae C. Kim, Graduate Student, Il H. Ryu, Graduate Student, and Kyeong U. Kim, ASAE Memb er Engineer , Professor, Seoul National University, Suwon, Korea. Corresponding author: Kyeong Uk Kim, School of Bio–Resources and Material Engineering, College of Agriculture and Life Sciences, Seoul National University, 441–744 Suwon, Korea; phone: 82–31–290–2382; fax: 82–31–297–7478; e–mail: [email protected]. the previous studies related to the measurement and analysis of transmission loads for agricultural tractors was made by Gerlach (1966). He measured the forces impo sed on a tractor transmission under the various service conditions and analyzed their characteristics. According to the results of his study, the peak torque in the transmission did not exceed about 2.5 times the rated engine torque. Grubisic (1994) showed how to construct a load spectrum from which the fatigue life of a machine component can be predicted. Renius (1976) developed a tractor load spectrum using a large amount of the operational load data collected in the European countries. His load spectrum has been used for the fatigue design of tractor transmissions. The objective of this study was to construct the representative spectra of the torque loads acting on the input shaft of the transmission and the final drive shaft of a tractor during plowing operations in Korea. It was also intended to investigate the effects of plowing speed and soil condition on the load spectrum. CHARACTERISTICS OF PLOWING OPERATIONS IN KOREA In order to investigate the operational characteristics of plowing operations, a survey was conducted on 36 tractors located in 19 different areas where relatively large plowing loads have been experienced. The surveyed tractors were in a range of 35 to 52 horsepower and were produced by the same manufacturer. Results of the survey showed that the most common gears selected for tillage were mid 4th (M4) and high 1st (H1) in a 4 (low–low, low, mid, high) Ü 4 (1st, 2nd, 3rd, 4th) synchro–mesh gear transmission, resulting in plowing speeds of 7.6 km/h and 10.3 km/h, respectively. The tillage depth varied from 10 to 30 cm. The annual use of a T

Documents

Analysis of Tractor Transmission Pm2805