In the case of TV products, space constraints and design requirements make it advantageous to use a worm gear that has a small volume and a self-locking function. Single enveloping worm gear teeth are classified as ZA, ZN, ZK, ZI, and ZC according to international standards. However, combining worm shafts and worm wheels with different tooth profiles can significantly worsen meshing transmission errors and reduce the lifespan of the worm gear. Despite these challenges, due to processing limitations, ease of manufacturing, and cost reduction, combinations of worm shafts and worm wheels with different tooth profiles are still considered. In this study, we confirmed the meshing transmission error for a worm gear that combined a ZA tooth shape worm shaft with a ZI tooth shape worm wheel. Additionally, we examined the contact stress and fatigue life characteristics of the material combinations using finite element analysis (FEM).
The purpose of this paper was to develop a simulation model for a 40 kW electric tractor using a powertrain based on dual motors and a planetary gear. To select motor capacity and reduction gear ratio based on the power flow for agricultural work, load data for various gear conditions were acquired and analyzed using a 42 kW engine tractor of similar capacity. Modeling was conducted using MATLAB/Simulink/Simscape. Load data acquired through actual field tests were applied as load conditions for the simulation. Simulation results confirmed that the power was transmitted through the planetary gear as the clutch and brake operated according to the work mode. The developed simulation model is expected to be used for electric tractor development.
Strain wave gears are widely used as reducers in robots, including collaborative and industrial robots. As a key component, they play a crucial role in determining overall robot performance. To enhance their effectiveness, various studies have focused on directly measuring the performance of assemblies or predicting the performance of individual components through analysis. However, there is a notable lack of research that experimentally measures and compares the physical properties of the circular spline, flexspline, and wave generator—the primary elements of strain wave gears. In this paper, we developed equipment to measure the radial stiffness of the flexspline, one of the key components, and validated its reliability through preliminary experiments. Furthermore, we measured and compared the radial stiffness of flexsplines produced by three different manufacturers. These findings are expected to provide valuable insights for improving the performance of strain wave gears and advancing robotics technology.
Automatic transmissions, which have the advantages of compact structure and smooth shifting, are installed in various vehicles with engines and hybrid power sources. Research and development are continuously being conducted to improve power and fuel efficiency. In this study, the influence of helix direction and helix angle of the planetary gear set on thrust-bearing power loss in an automatic transmission was analyzed. A sample automatic transmission model was constructed to analyze the axial load and bearing relative rotation speed, which are the main factors in thrust-bearing power loss. The relative rotation speed of the bearing was analyzed using the sample model, and the thrust-bearing load in the axial direction was analyzed according to the helix direction of the planetary gear set constituting the model and the helix angle of the planetary gear set. The power loss occurring in thrust-bearing was derived using the analysis results of relative rotational speed and load, and the influence of the helix direction and helix angle of the planetary gear set was analyzed.
Development and research on electric vehicles in power transmission system are increasing as the demand for ecofriendly and autonomous vehicles increases across the industry. In order to reduce noise, research on high efficiency and low noise due to electrification of the gearbox system is being actively conducted, such as applying design technology to optimize the shape of the gear and increase rigidity. In particular, research on low noise is active because the noise of the electric gearbox could be easily recognized in a vehicle, even with small noise due to its frequency characteristics. Therefore, in this study, effects of main specifications of gears on noise and power loss were studied and analyzed through a Parametric Study. Characteristics of the proportional relationship between noise and power loss according to major specifications were analyzed. Based on study results, NVH analysis in the gear system was performed. After that, actual data were secured through test measurements and a noise reduction effect of 4.4 dB was confirmed.
Gearboxes used in the drivetrain of intelligent robots are key mechanical components that play a significant role in determining the performance of modern robotic systems. Gearboxes employing the planetary gear mechanism, known to achieve a wide range of reduction ratios while remaining relatively cost-effective, have recently been adopted in robot drivetrains. In this paper, we utilize domestic technology to fabricate a gearbox using a compound planetary gear mechanism and conduct an evaluation of eight performance aspects of the developed gearbox through the fabrication of a dynamometer and a jig. The dynamometer comprised of the gearbox, input motor, input-output torque sensors, and a powder brake. By driving the input motor and applying braking force with the powder brake, we compare input torque sensor values with output torque sensor values to derive results. A test jig is created, consisting of an input motor, gearbox, and encoder sensor, for the measurement of inverse operation characteristics and backlash. By conducting a performance evaluation of the developed high-strength, high-reduction-ratio compact planetary gearbox, we validate the potential of the testing system and extend the scope of domestic gearbox technology development.
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Three-dimensional reconstruction of gearbox from multi-view point clouds with surface feature parfameter measurement method Jian Chen, Zhijia Zhang, Guanghui Liu, Dejian Li, Qiushuang Li Engineering Research Express.2025; 7(4): 045253. CrossRef
This study performed high-frequency heat treatment experiments and simulations of the park gear of an automobile transmission. The heating temperature and hardening depth were measured during high-frequency heat treatment. Moreover, by applying the resonance RCL circuit, the current value of the coil during high-frequency heat treatment, the electromagnetic and heat transfer material properties dependent on the temperature, and the phase transformation function were all applied to the simulation. In the high-frequency heat treatment experiment, the heating temperature was 977.4℃ and the 1st direction hardening depth was 1.5 mm, the 2nd direction hardening depth was 3 mm, and the 3rd direction hardening depth was 2.5 mm, and the reliability was verified by comparing the simulation heating temperature of 1,097℃ and the 1st direction predicted hardening depth of 1.6 mm, the 2nd direction predicted hardening depth of 2.8 mm, and the 3rd direction predicted hardening depth of 2.7 mm. The error rate of the heating temperature results was 12.2% whereas that of the hardening depth results was 7.1%.
The gear overlap ratio shows the characteristics of the spur gear and the helical gear and varies according to the torsional angle. The gear ratio, tooth width, and center distance, which are restricted in a space of performance and manufacturing and design in the gearbox, are fixed. A parametric study on modules, the number of teeth, and torsion angles was conducted to analyze the relationship between the overlap ratio and PPTE. Then, contact analysis was performed by correcting the tooth profile to improve the transmission error. Contact analysis was performed through correction of the tooth modification to improve transmission error, and the noise was analyzed according to the overlap ratio by applying a noise prediction equation.
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Study on the Modification of the Contact Pattern and Teeth Shape of Tapping Device Drive Gears Sung-Min Moon, Yong-Woo Park, Do-Young Lee, Sung-Ki Lyu Journal of the Korean Society of Manufacturing Process Engineers.2025; 24(9): 76. CrossRef
A Study on the High Efficiency and Low Noise Design of Electric Industrial Gearboxes Nam Yong Kim, Jin-Uk Baek, Sung Ki Lyu Journal of the Korean Society for Precision Engineering.2024; 41(4): 243. CrossRef
Optimal Design of Surface Pressure Strength to Prevent Gear System Pitting Phenomenon Gi-Myung Gwak, Jin-Uk Baek, Nam-Yong Kim, Sung-Ki Lyu Journal of the Korean Society of Manufacturing Process Engineers.2024; 23(1): 76. CrossRef
Development of a Prediction Model for the Gear Whine Noise of Transmission Using Machine Learning Sun-Hyoung Lee, Kwang-Phil Park International Journal of Precision Engineering and Manufacturing.2023; 24(10): 1793. CrossRef
The gear has a wide range of transmitted force as various gear ratios are possible using a combination of teeth. It can transmit power reliably and cause relatively little vibration and noise. For this reason, the application of reducers of electric vehicles is being expanded. Vibration noise generated from gears is propagated into the quiet interior of a vehicle, causing various claims. In most gear studies, transmission error has been pointed out as the main cause of vibration noise of gears. Transmission errors have various causes, including design factors, manufacturing factors, and assembly factors. In general, when predicting transmission error through finite element analysis, design factors play an important role without considering manufacturing factors or assembly factors. In this study, relationships among important design variables (gear module, compensation rate, load torque, and transmission error) in gear design were investigated using analytical and experimental methods. In addition, a method of predicting gear meshing stiffness through the predicted gear transmission error was proposed to obtain variation of meshing stiffness due to changes of gear design parameters.
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Development of a Prediction Model for the Gear Whine Noise of Transmission Using Machine Learning Sun-Hyoung Lee, Kwang-Phil Park International Journal of Precision Engineering and Manufacturing.2023; 24(10): 1793. CrossRef
Failure of conventional snowplows is usually caused by the strain put it its rotational parts. In the case of the vertical rotation, when the snowplow is rising or falling, the sensor automatically stops the rotation and the wire could be break due to the impact from an endless drive in the reverse direction or conversely from the winding of the wire. While in motion, snowplows are frequently over turned due to their heavy weight. Snowplows are manufactured with conventional steel plates and have heavy hydraulic cylinders which makes them heavy. This can result in the damaging of the vehicle due to the mounted snowplow and its malfunctions. In this study, a composite resin blade with a high-strength and is lightweight was developed for a snowplow. In order to ensure durability of the snowplows, a new bobbin was designed to mimic the clutch of a vehicle. This study was developed to eliminate the tension and fatigue of the wire by winding the chain instead of the wire in the newly designed bobbin.
Gears are rotating mechanical parts with excellent power transmission efficiency and are widely used in machine tools, automobile, industrial machinery, and aviation industries. To enhance the performance of the gear, optimized design of the gear geometry is paramount. In this paper, we optimize the geometric tooth profile of helical gears which are among the gears of the transfer case gearbox by using the finite element program, Romax Designer to model and analyze the load and gear teeth of the gearbox power transmission system. The optimized gears were fabricated and compared to the results of the gear tests.
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Study on the Modification of the Contact Pattern and Teeth Shape of Tapping Device Drive Gears Sung-Min Moon, Yong-Woo Park, Do-Young Lee, Sung-Ki Lyu Journal of the Korean Society of Manufacturing Process Engineers.2025; 24(9): 76. CrossRef
The gear ratio variable topology of a magnetic gear with an integrated harmonic modulator is analyzed using a magnetic permeance model. A dynamic characteristic equation is derived in consideration of the gear ratio between each layer constituting the magnetic gear: the driving side, the driven side, and the control side layer. Based on derived transfer function, the frequency characteristic between driving torque and angular speed of the driving side is analyzed. Theoretic model is compared with an experimental test result using the in-house dynamometer. In the general magnetic gears, the gear ratio is variable so that speed between each layer decelerates with gear ratio, but transmission torque is constant regardless of gear ratio. In this study, these characteristics are also verified through theoretical methods and experimental results, respectively.
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Torque Handling of a Magnetic Gear with a Variable Gear Ratio by Superposition of Multi-phase Currents Kwang Suk Jung Journal of the Korean Society of Manufacturing Technology Engineers.2019; 28(6): 446. CrossRef
The differential gear distributes the power from the transmission shaft to both wheel axles and automatically ensures rotational difference to maintain the speed difference between the two axles. However, when the vehicle travels on a slippery road surface, a slip in the wheel induces improper transmission of the driving force. Therefore, the limited slip differential limits the function of the differential gear by transmitting the driving force to the normal wheel without the slip. The hydraulic differential limiting device is based on the principle that the fluid between the inner and the outer rotors is compressed by the rotation of the trochoidal gear, and the compressed fluid moves to the cylinder to generate sufficient pressure in the side pinion gear to limit the differential. In this study, the pressure is predicted by variation in viscosity and rotational speed through flow analysis.
The aim of this study is to design the gearbox of an electric vehicle using the rear-wheel drive. The gearbox is a set of revolving gears and shafts based on programmed torque and rotations per minute (rpm). In this case, safety, strength and durability of gears and shafts was considered. In the narrow vehicle, a light case is used. In addition to gear safety and deflection, the weight of the vehicle was reduced. The electric vehicle reducer gearbox was modeled according to the vehicle room. The strength analysis was conducted using finite element method (FEM). After analyzing the strength using FEM to verify stress distribution, the design was modified, and compared with the results of altered design using FEM. As a result, the reducer gearbox of electric vehicle was designed according to incorporate gear safety, deflection of each gear, durability, and analysis of finite elements followed by test assessment, vehicle installation and the production of real parts.
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Sensitivity Analysis on Driving Characteristics According to Change in Gear Ratio of a Front Wheel Drive Electric Vehicle Young-Kap Son, Jeong-Min Kim Journal of the Korean Society of Manufacturing Process Engineers.2022; 21(9): 50. CrossRef
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Simulation and experimental study on lubrication of high-speed reducer of electric vehicle Fuchun Jia, Yulong Lei, Xianghuan Liu, Yao Fu, Jianlong Hu Industrial Lubrication and Tribology.2021; 73(3): 500. CrossRef
Study on the Reduction of Gear Whine Noise in Diesel Engine Gear Train Qi Zhang, Yong Bo Wang, Jian Hua Lv, Zhong Gang Zhu, Zhen Qin, Sung Ki Lyu Journal of the Korean Society for Precision Engineering.2019; 36(9): 867. CrossRef
A Study on the Optimal Design of Drive Gear for Transfer Gearbox MyeongJin Song, MyeongHo Kim, Zhen Qin, DongSeon Kim, NamSool Jeon, SungKi Lyu Journal of the Korean Society for Precision Engineering.2019; 36(2): 121. CrossRef
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