Original Article J. Biosyst. Eng. 43(2):83-93. (2018. 6) https://doi.org/10.5307/jbe.2018.43.2.083 Journal of Biosystems Engineering eissn : 2234-1862 pissn : 1738-1266 Consumed-Power and Load Characteristics of a Tillage Operation in an Upland Field in Republic of Korea Jeong-Gil Kim 1, Young-Joo Kim 1, Jung-Hun Kim 2, Beom-Soo Shin 3, Ju-Seok Nam 3 * 1 Convergence Components & Agricultural Machinery Group, Korea Institute of Industrial Technology, Gimje, Republic of Korea 2 Tongyang Moolsan Co., Ltd., Gongju, Republic of Korea 3 Department of Biosystems Engineering, Kangwon National University, Chuncheon, Republic of Korea Received: February 25 th, 2018; Revised: April 2 th, 2018; Accepted: April 29 th, 2018 Purpose: This study derived the consumed power and load characteristics of a tillage operation performed in an upland field located in Seomyeon, Chuncheon, Rep. Korea, where potatoes and cabbages were cultivated in two crops. Methods: A plow and rotavator were mounted on a tractor with 23.7 kw of rated power to perform the tillage operation. The work conditions were determined, considering the actual working speed of the tillage operation performed by the local farmers. The power consumption of the rear axle, engine, and power take-off (PTO), PTO torque, and tractive force were measured under each work condition. The consumed power and load characteristics were analyzed using their average values. Results: The rotary-tillage operation consumed more engine power than the plow operation for the same tractor-transmission gear condition. The PTO in the rotary-tillage operation and the rear axle in the plow operation consumed the most power. The power consumption of the engine and the PTO for the rotary-tillage operation tended to increase as the transmission gears of the tractor and the PTO became higher. In contrast, the rear-axle power consumption was insignificant. In addition, the PTO torque tended to rise as the tilling pitch increased. For the plow operation, the drawbar power and the rear axle power accounted for 68 90% of the engine power. The engine and rear axle power, drawbar power, and tractive force tended to rise as the working speed increased. Conclusions: The power consumption and load characteristics differed for the plow and rotary-tillage operations. They may also differ depending on the soil conditions. Therefore, the power consumption and load characteristics in various work environments and regions should be analyzed, and reflected in the design of tractors and working implements. The results derived from this study can be used as a reference for such designs. Keywords: Consumed power, Load, Plow operation, Rotary tillage operation, Upland field Introduction Tillage is the process of softening the soil by pulverizing and reversing it; this creates a land surface that is suitable for crop cultivation. This process is an essential farming operation for all outdoor crop cultivation because it facilitates sowing or transplanting and creates an environment favorable for crop growth. Plows and rotavators are the representative farming devices for tillage. Plows are used for the primary tillage, in which hardened *Corresponding author: Ju-Seok Nam Tel: +82-33-250-6497; Fax: +82-33-259-5561 E-mail: njsg1218@kangwon.ac.kr soil is reversed, cut, and crushed into large lumps. Rotavators are used for the secondary tillage, in which the soil from the primary tillage is crushed into small grains. Both primary and secondary tillage operations can be completed simultaneously using deep-tillage rotavators; however, performing primary and secondary tillage in sequence is common in Rep. Korea. In addition, the proportion of power-operated tillage, in which the plows and rotavators are mounted on tractors and operated using power transmitted from the tractor, is high (Myung and Lee, 2009). Plowing and rotary-tillage operations represent more than 70% of the annual tractor-use hours. They consume the Copyright c 2018 by The Korean Society for Agricultural Machinery This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
most power among various farming tasks performed with tractors (Kim et al., 2011a). In addition, among various farming machines, tractors exhibit the highest annual supply and the most annual working days (KAMICO and KSAM, 2017). Therefore, tillage operations using tractors are major agricultural tasks for outdoor crop cultivation. The work characteristics of the tillage operation should be considered in the design of tractors and working implements. The load and the power level required for the tillage operation should be identified for the efficient use and robust design of tractors and working implements. A tillage operation involves an interaction between the soil and the working implements. In this case, the soil exhibits a non-linear and plastic behavior. In addition, various variables related to the soil and the implements affect the tillage characteristics (ASAE Standards, 2015); hence, it is very difficult to derive a highly accurate tilling load and power using theoretical and analytical methods. To obtain accurate tilling load and power values, the load and consumed power should be measured while the tillage operation is performed in an actual field. Kim et al. (1997) measured the torque during a rotarytillage operation in an artificial soil bin for three different soil types. Kim et al. (1998) measured the torque of the transmission input shaft and the driving axle during a plow operation in two paddy fields and two upland fields (Kim et al., 1998). Wu et al. (2001) measured the torque of the transmission input shaft and the driving axle during a rotary-tillage operation in a wet paddy field using a 30-kW-class tractor. Meanwhile, Myung and Lee (2009) measured the power consumed during a rotary-tillage operation in three upland fields and one paddy field using a 49-kW-class tractor. Park et al. (2010) measured the PTO power consumption during plow and rotary-tillage operations in three paddy fields using a 37-kW-class tractor. Kim et al. (2011a) measured the power consumption of the driving axle, PTO, and hydraulic device during plow and rotary-tillage operations in three paddy fields using a 28-kW-class tractor. Kim et al. (2011b) measured the PTO torque during a rotary-tillage operation in ten paddy fields and ten upland fields using a 30-kW-class tractor. Nam et al. (2012) measured the power consumption and the torque of the PTO during a rotary-tillage operation using a 53-kW-class tractor. Kim et al. (2013) measured the power consumption and the torque of the PTO during a rotary-tillage operation using a 48-kW-class tractor. Studies conducted so far focused on either plow or rotary-tillage operations, and measured the load or the consumed power in one or two limited tractor locations. For an overall understanding of the load and the power characteristics required in a tillage operation, both the load and the power in all main parts of the tractor should be measured for both plow and rotary-tillage operations. In this study, the load and the power characteristics Table 1. Specifications of a prime-mover tractor Item Specification Model/Company/Nation C320/Tongyang Moolsan/Rep. Korea Weight (kn) 14.2 Weight distribution ratio (front axle: rear axle, %) 43.2: 56.8 Length Width Height (mm) 3010 1390 2560 Minimum ground clearance (mm) 345 Engine Rated power (kw)/speed (rpm) 23.7/2600 PTO Transmission stage (rotational speed, rpm) 1 (540), 2 (750), 3 (1000) Table 2. Specifications of the plow and rotavator Item Specification Plow Rotavator Model/Company/Nation YP3-75H-C/Youngjin Machinery/Rep. Korea YJ140NS/Youngjin Machinery/Rep. Korea Weight (kn) 2.2 2.7 Length Width Height (mm) 1780 1000 1220 755 1650 930 Applicable tractor power (kw) 23.5 31.6 19.1 24.3 Nominal tilling width (mm) 750 1350 Nominal tilling depth (mm) 200 110 84
required by a tillage operation performed in an upland field of Chuncheon, Gangwon-do, Rep. Korea were analyzed. The tractive force and the PTO torque, as well as the power consumption of the engine, rear axle, and PTO were measured while plow and rotary-tillage operations were performed under various work conditions. Furthermore, the load and the power characteristics were analyzed according to the work conditions using the measurement results. Materials and Methods Test equipment Tractor Table 1 and Figure 1 show the major specifications and shape of the tractor used as the power source for the plow and rotary-tillage operations. The tractor had a four-wheel -drive transmission with four main transmission gears (1, 2, 3, and 4), three sub gears (L, M, and H), and three PTO gears (1, 2, and 3). It was developed for use in upland fields with compact features, but had a high minimum ground clearance suitable for passing over ridges. Plow and rotavator A plow and a rotavator, which are commonly used by farmers in Chuncheon, were used. The plow was a reversible type, capable of reversing the soil both in the left and right directions, using hydraulic power. The rotavator was a side-chain type, in which six Japanese rotary blades were mounted in each of the six flanges located on the rotor shaft. Table 2 presents the specifications of the plow and the rotavator, while Figures 2 and 3 illustrate their shapes. Test site The experimental field was a rectangular field located in Seomyeon, Chuncheon, and used to cultivate potatoes and cabbages in two crops (Fig. 4). The soil strength was measured at six different locations in the field, at up to 25-cm depths at 5-cm intervals in accordance with the standard testing method (ASAE EP542, 2009). The soil-cone penetrometer (SC900, Spectrum Technology, USA) for hard soil, specified in the standard specification (ASAE S313.3, 2009), was used. The moisture content was measured using the oven method (ASAE S526.4, 2015) with soil samples collected from six different Figure 1. Tractor used as a prime mover. Figure 3. Rotavator used in this study. Figure 2. Plow used in this study. Figure 4. View of the experimental field. 85
Table 3. Soil properties of the experimental field Soil texture Sandy Moisture content [dry basis (d.b.)](%) Location A: 19.7 Location B: 24.2 Location C: 20.5 Location D: 19.5 Location E: 23.4 Location F: 23.5 Soil strength by depth (kpa) Location 5 cm 10 cm 15 cm 20 cm 25 cm 1 1518 1898 3554 3278 3070 2 1690 552 2450 2553 3312 3 2242 2794 2415 2484 3140 4 552 828 1000 1208 1518 5 1484 1449 1484 1622 3243 6 794 656 2036 2380 2794 Table 4. Work conditions for field test Type of operation Gear of Tractor/PTO Rated working speed (km/h) L4/1 L4/2 L4/3 1.99 Rotary tillage M1/1 M1/2 2.57 M2/1 M2/2 3.53 L4 1.99 Plow M1 2.57 M2 3.53 M3 4.54 (a) Plow operation Figure 5. View of field operations. (b) Rotary-tillage operation locations in the field. The soil texture was determined using the U.S. Department of Agriculture (USDA) method. Table 3 shows the measured soil strength, moisture content, and soil texture. The soil strength of the field was in the range of 552 3554 kpa, and the moisture content ranged from 19.5 to 24.2%. The soil texture was sandy, with sand accounting for 90.9%, followed by silt (6.0%), and clay (3.1%). Work conditions Table 4 shows the work conditions for the plow and rotary-tillage operations. The transmission gears of the tractor were determined, considering the actual working speed of the tillage operation performed by the local farmers. The work for the rotary-tillage operation was performed using the L4, M1, and M2 tractor gears. In this case, the PTO could perform work in three different gears, but it could only use the L4 gear of the tractor, not the M1 and M2 gears. Meanwhile, the work for the plow operation was performed in the L4, M1, M2, and M3 gears of the tractor, and the PTO power was not used. The engine speed maintained the rated speed for each condition, and the working length ranged from 30 to 50 m. The rotary-tillage operation was performed twice under each condition, while the plow operation was conducted 86
two to four times according to the condition. Figure 5 depicts the plow and rotary-tillage operations on the field. Measurement and analysis The power consumption of the engine, PTO, and rear axle were measured to analyze the consumed-power characteristics of the tillage operation. To analyze the load characteristics, the tractive force was measured for the plow operation, while the PTO torque was measured for the rotary-tillage operation. A torque meter was attached to the PTO shaft to measure the PTO torque and the rotational speed (Fig. 6). Table 5 presents the torque meter specifications. The signals from the torque meter were acquired using a telemetry system with specifications shown in Table 6. The torque of the rear wheels was measured using two-element 90 rosette strain gauges (CEA-06-062UV- 350, Micro Measurements Co., USA) attached to the left and right wheel shafts (Fig. 7). The signals of the strain gauges were calibrated through experimentation with a torsion tester (215.45C, MTS Inc., USA) (Fig. 8). The calibration range in this case was set between 1000 and 1000 N m, considering the magnitude of the torque applied to the rear wheels. Figure 9 shows the calibration test results. The rotational speed of the rear wheels was measured using proximity sensors (MP-981, Ono Sokki Co., Japan) attached to the left and right wheel shafts. The measured torque and the rotational speed signals were also acquired using the telemetry system (Table 6). The torque and the rotational speed of the engine were measured by acquiring data from the electronic control unit (ECU) through controller area network (CAN) communication. The actual working speed of the tractor was measured using a radar sensor attached to the front of the tractor. Table 7 and Figure 10 present the specifications of the radar sensor and its installation on the tractor. A six-component load cell (Kim et al., 2017) was attached to the three-point hitch on the tractor to measure the tractive force during the plow operation (Fig. 11). The six-component load cell can measure the tractive force with an error rate less than 1.5%. Figure 6. Torque meter for torque and speed measurement. Table 5. Specifications of the torque meter Item Specification Company/Nation Manner/Germany Type PTO flange Measuring range (N m) 5,000 Temperature range ( ) 25 85 Accuracy class (%) < 0.3 Figure 7. Strain gauge for rear-wheel torque measurement. Table 6. Specifications of the telemetry system Item Specification WS-TAS1-STG (transmitter part) & Model/Company/Nation WS-TRS1 (receiving part) /WS Engineering/Rep. Korea Maximum distance (m) 50 Signal bandwidth (Hz) 0 500 Sampling rate (Hz) 1200 Resolution (bit) 16 System accuracy (%) < 0.2 Figure 8. Experiment for strain-gauge signal calibration. 87
Table 7. Specifications of the radar sensor Item Specification Model/Company/Nation RADAR II/DICKEY-john/USA Velocity range (km/h) 0.53 96.6 Accuracy (%) 5 Mounting angle ( ) 35±5 Mounting height (mm) 610 2,438 The power consumption of the PTO, engine, and rear wheels were determined through Eq. (1), which used the measured rotational speed and the torque. The power consumption of the rear axle was obtained by adding the power consumption of the left and right wheels. The drawbar power during the plow operation was determined through Eq. (2), which used the actual working speed and the measured tractive force. The tilling pitch, which was the length of the ground-surface tillage in the forward direction caused by each tillage-blade rotation, affected the tillage performance in the rotary-tillage operation (Kim et al., 1997). Therefore, the ratio of the actual working speed to the rotational speed of the PTO shaft was defined as shown in Eq. (3) to investigate the influence of the tilling pitch. The magnitude of the speed ratio λ was proportional to that of the tilling pitch. п (1) where P r = Rotational power (kw) T = Torque (N m) N = Rotational speed (rpm). (2) where P d = Drawbar power (kw) F = Tractive force (kn) V = Actual working speed (km/h). (3) where λ= Speed ratio (km/h rpm) N p = Rotational speed of PTO shaft (rpm). (a) Left wheel (b) Right wheel Figure 9. Results of calibration test for rear-wheel strain gauges. Figure 10. Radar sensor for actual working-speed measurement. Figure 11. Six-component load cell for tractive-force measurement. 88
The data sampling rate was set to 100 Hz, considering the actual working speed and the rotational speed of the PTO shaft. The measurement was started when the engine reached the rated speed. Filtering was performed by applying the moving average to the measured data. The data were analyzed using the average values of the repeated tests; twice for the rotary-tillage operation and two to four times for the plow operation. Results and Discussion Consumed power and load characteristics for the rotary-tillage operation Figure 12 shows the measured power consumption of the engine, PTO, and rear wheels as well as the PTO torque for the rotary-tillage operation, performed with the tractor gears and the PTO set to L4 and 1, respectively. The power consumption of the left and right wheels on the rear axle were almost identical, regardless of the work conditions. Table 8 shows the power consumption of the engine, ratio of the PTO power consumption to the engine power, ratio of the rear-axle power consumption to the engine power, PTO torque, and speed ratio (λ) obtained under each work condition. The power consumption of the engine was 72 95% of the rated power of the tractor, while the power consumption of the PTO was 63 76% of the engine power, depending on the work conditions. The power consumption of the engine and the PTO tended to rise as the PTO gear increased under the same tractor gear condition, and as the tractor gear increased under (a) Engine power (b) PTO power (c) Rear wheel power (d) PTO torque Figure 12. Consumed power and load characteristics for rotary tillage operation with gear L4/1. Table 8. Power and load characteristics for rotary-tillage operation Gear of Tractor/ PTO Engine power, kw PTO power/ Engine power Rear-axle power/ Engine power PTO torque, N m Speed ratio, km/h rpm L4/1 17.099 0.629 0.034 172.454 0.00302 L4/2 20.323 0.689 0.027 171.537 0.00229 L4/3 22.206 0.673 0.029 134.771 0.00170 M1/1 18.001 0.651 0.034 185.524 0.00394 M1/2 22.341 0.703 0.024 192.056 0.00297 M2/1 20.656 0.706 0.032 235.626 0.00540 M2/2 22.370 0.760 0.027 226.536 0.00408 89
the same PTO-gear condition. The rear-axle power consumption did not exhibit significant differences under different work conditions, and was only 2.4 3.4% of the engine power. The PTO torque ranged from 134 to 236 N m and tended to rise as the speed ratio (i.e., tilling pitch) increased. However, the power consumption of the (a) Engine power (b) PTO power (c) Rear wheel power (d) PTO torque Figure 13. Consumed power and load characteristics according to speed ratio in rotary tillage operation. (a) Engine power (b) Drawbar power (c) Rear wheel power (d) Tractive force Figure 14. Consumed power and load characteristics for plow operation with gear L4. 90
engine, rear axle, and PTO did not show any correlation with the tilling pitch (Fig. 13). Consumed power and load characteristics for the plow operation Figure 14 shows the power consumption of the engine, drawbar power, power consumption of the rear wheels, and tractive force measured when the plow operation was performed with the tractor gear set to L4. The power consumption of the left and right wheels on the rear axle were almost identical, regardless of the work conditions. Table 9 and Figure 15 show the power consumption of the engine, ratio of the drawbar power to the engine power, ratio of the rear axle power consumption to the engine power, and tractive force obtained under each work condition. The power consumption of the engine was 37 84% of the rated power of the tractor. The drawbar power was 27 40% of the engine power depending on the work conditions. The power consumption of the rear axle was 41 51% of the engine power. Therefore, the drawbar power and the power consumption of the rear axle represented 68 90% of the engine power. The power consumption of the engine and the rear axle, drawbar power, and tractive force tended to rise as the tractor gear (i.e., working speed) increased. The tractive force ranged from 4.8 to 7.0 kn. Conclusions In this study, the consumed power and the load (a) Engine power (b) Drawbar power (c) Rear wheel power (d) Tractive force Figure 15. Consumed power and load characteristics according to transmission gear in plow operation. Table 9. Power and load characteristics for rotary-tillage operation Tractor Gear Engine power, kw Drawbar power/ Engine power Rear axle power/ Engine power Tractive force, kn L4 8.930 0.275 0.411 4.836 M1 10.898 0.279 0.438 4.725 M2 16.172 0.316 0.509 6.054 M3 19.755 0.398 0.497 6.986 91
characteristics for a tillage operation performed in an upland field of Chuncheon, Gangwon-do were analyzed. A plow and a rotavator, which are commonly used in Chuncheon, were mounted on a tractor with 23.7 kw of rated power to perform the tillage operation. The transmission gears of the tractor were set to L4 M3, while those of the PTO were set to 1 3, considering the actual working speed of the tillage operation performed by the local farmers. The tractive force and the PTO torque as well as the power consumption of the engine, rear axle, and PTO were measured, while the plow and rotary-tillage operations were performed under each work condition. The experimental field was an upland field filled with sand, located in Seomyeon, Chuncheon. Its moisture content ranged from 19.5 to 24.2%. The results of this study are summarized as follows: (1) The power consumption of the engine was 72 95% of the tractor s rated power for the rotary-tillage operation and 37 84% for the plow operation. The rotary-tillage operation consumed more power than the plow operation under the same tractor gear condition. (2) The power consumption of the PTO was 63 76% of the engine power for the rotary-tillage operation. The power consumption of the rear axle for the plow operation was 41 51% of the engine power. Therefore, the PTO consumed the most power in the rotary-tillage operation, while the rear axle consumed the most power in the plow operation. (3) The power consumption of the engine and the PTO for the rotary-tillage operation tended to rise as the tractor and PTO gears increased. The power consumption of the rear axle was not significant. The PTO torque tended to rise as the tilling pitch increased. (4) The drawbar power and the power consumption of the rear axle for the plow operation accounted for 68 90% of the engine power. In addition, the power consumption of the engine and the rear axle, as well as the drawbar power and the tractive force, tended to rise as the working speed increased. Conflict of Interest No potential conflict of interest relevant to this article was reported. Acknowledgment This study was supported by the Korean Evaluation Institute of Industrial Technology (KEIT) through Projects for industrial technological innovation, funded by the Ministry of Trade, Industry, and Energy (MOTIE) (10067768). This study was also supported by 2017 Research Grant from Kangwon National University. References ASAE Standards. 2009. EP542 FEB1999(R2009): Procedures for using and reporting data obtained with the soil cone penetrometer. St. Joseph, MI: ASABE. ASAE Standards. 2009. S313.3 FEB1999(R2009): Soil cone penetrometer. St. Joseph, MI: ASABE. ASAE Standards. 2015. D497.7 MAR2011(R2015): Agricultural machinery management data. St. Joseph, MI: ASABE. ASAE Standards. 2015. S526.4 SEP2015: Soil and water terminology. St. Joseph, MI: ASABE. KAMICO and KSAM. 2017. Agricultural machinery yearbook Republic of Korea. Korea Agricultural Machinery Industry Cooperative and The Korean Society for Agricultural Machinery, Cheonan and Jeonju, Rep. Korea. (In Korean) Kim, S. S., Y. S. Lee and J. K. Woo. 1997. Study on the improvement of rotary blade tilling load characteristics analysis of the three kinds of rotary blade -. Journal of Biosystems Engineering 22(4): 391-400. (In Korean, with English abstract) Kim, D. C., K. U. Kim and J. W. Lee. 1998. Development of a load spectrum of tractor transmission. Journal of Biosystems Engineering 23(6): 539-548. (In Korean, with English abstract) Kim, Y. J., S. O. Chung, S. J. Park and C. H. Choi. 2011a. Analysis of power requirement of agricultural tractor by major field operation. Journal of Biosystems Engineering 36(2): 79-88. (In Korean, with English abstract) https://doi.org/10.5307/jbe.2011.36.2.79 Kim, Y. J., S. O. Chung, C. H. Choi and D. H. Lee. 2011b. Evaluation of tractor PTO severeness during rotary tillage operation. Journal of Biosystems Engineering 36(3): 163-170. (In Korean, with English abstract) https://doi.org/10.5307/jbe.2011.36.3.163 Kim, M. H., J. S. Nam and D. C. Kim. 2013. Comparison of 92
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