• Proceedings of the KSR Conference
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• 1999.11a
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• pp.99-106
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• 1999

Because many light rail transit systems are mainly operated in the downtown areas of a large cities and the congestion areas, there are many steep gradients and sharp radius sections in that lines. As that reasons above, light rail vehicles are equipped with differential gear units between traction motors and final reduction gear units. In this paper, the configurations and the interferences of 2K-H I type Planetary gear train, which is applicable for light rail vehicles and based on various differential gear units, are studied. The ranges of addendum modification coefficients which would not lead to interferences is analyzed, and optimal addendum modification coefficients among these ranges are presented, which generate the maximum efficiency of planetary gear drives and differential gear unit as pressure angles, speed ratios,

• Journal of the Korean Society for Railway
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• v.4 no.2
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• pp.55-61
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• 2001

Since the plug type passenger door has two modes of motion, a power transmission unit must be capable of plug-in or plug-out mode, and sliding mode. Complex planetary gear train is proposed, which is composed of two 2K-H, I type planetary gear units. For the proposed complex planetary gear train, ranges of addendum modification coefficients which would not lead to interferences are analyzed, and optimal addendum modification coefficients among these ranges which generate the maximum efficiency are presented. Based on the results of analysis on interferences, efficiencies and torque ratios, the specifications for the complex planetary gear train were determined. It has been shown by tests of the complex planetary gear train manufactured that the gear train worked well with good agreements of analysis.

• Proceedings of the KSR Conference
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• 2001.05a
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• pp.170-177
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• 2001

Since plug type passenger door has two motion modes, power transmission unit must be capable of plug-in or plug-out, and sliding mode. Complex planetary gear train is proposed, which is composed of two 2K-H, I type planetary gear units. For the proposed complex planetary gear train, ranges of addendum modification coefficients which would not lead to interferences is analyzed, and optimal addendum modification coefficients among these ranges which generate the maximum efficiency are presented. Based on the interference, efficiency and torque ratio analysis results, complex planetary new train is designed and manufactured.

• Journal of Drive and Control
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• v.13 no.4
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• pp.45-51
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• 2016

The power train of a hydro-mechanical, continuously variable transmission for forklifts makes use of hydro-static units, hydraulic multi-wet disc brakes & clutches, and complex helical & planetary gears. The complex helical & planetary gears are very important parts of the transmission because of a strength problem. In the present study, we calculated the specifications of the complex helical & planetary gear train, and analyzed the gear bending and compressive stresses of the gears. It is necessary to analyze the gear bending and compressive stresses thoroughly for optimal design of the complex helical & planetary gears with respect to cost and reliability. In this paper, we analyze the actual gear bending and compressive stresses of complex helical & planetary gears using the Lewes & Hertz equation, and we also verify the calculated specifications of the complex helical & planetary gears by evaluating the results of the data of allowable bending and compressive stress using the Stress vrs Number of Cycles curves of gears.

• Journal of Drive and Control
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• v.14 no.4
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• pp.71-78
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• 2017

The power train of hydro-mechanical continuously variable transmission (HMCVT) for 8-ton class forklift includes hydro-static units, hydraulic multi-wet disc brake & clutches and complex helical & planetary gears. The helical & planetary gears are key components of HMCVT's power train wherein strength problems are the main concerns including gear bending stress, gear compressive stress, and scoring failure. Many failures in power train gears of HMCVT are due to the insufficient gear strength and resonance problems caused by major excitation forces, such as gear transmission error of mating gear fair in the transmission. In this study, wherein excitation frequencies are the gear tooth passing frequencies of the mating gears, a Campbell diagram is used to calculate the power train gears' critical speeds. Mode shapes and natural frequencies of the power train gears are calculated by CATIA V5. These are used to predict resonance failures by comparing the actual working speed range with the critical speeds due to the gear transmission errors of HMCVT's power train gears.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.6
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• pp.806-815
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• 2010

Gear trains are combined with the planetary gear units and helical gear units. It is known that the combination type is decisive to the system performances of the transmissions. In this paper, within the commonly used range of the design requirements for medium and large scaled (1~8 MW) wind turbines, the transmission characteristics of the typical layouts of the gear train are investigated. According to the international standard by ANSI/AGMA/AWEA 6006-A03, the gear boxes are basically designed and compared with respect to the system lifes of 99% reliability, total weight, the power densities, overall diameter/length and the maximum stresses of the gear teeth. With these comparison works, the characteristics of the layouts of gear trains are discussed.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.1
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• pp.34-43
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• 2007

As a method to improve the poor torque capacity on the continuously variable transmission(CVT), power splitted devices(PSD) reducing the power entering into the transmission has been considered. But this kind of PSD requires for the variator to be a large coverage of the speed ratio (CSR) Since the CSRs of the well-known push belt or the toroidal ones are not enough large, the power splitted CVTs (PSCVTs) using them should be made with multiple modes. inevitably adding the do9 clutches and the associated accessories. In this paper a PSCVT with single mode is conceptually designed A new continuously variable unit (CVU) consisting of the paired inner and outer spherical rotors is used. The CVU has large CSR and excellent compactness. As a PSD. a variable bridge (VB) using the Planetary gear units (PGUs) is considered because it has an upper bound on the power ratio. An optimal design to minimize the effective efficiency of the PSCVT is carried out. Through the performance analysis on the designed model, good expectation on the practicability in the heavy vehicle system is shown.

• International Journal of Automotive Technology
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• v.8 no.6
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• pp.799-806
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• 2007

One method for improving the torque capacity of the CVT is to use a split-powered CVT(SPCVT) to reduce the power transmitted into a continuously variable unit(CVU). A variable bridge SPCVT with two planetary gear units(PGUs), which are composed of a sun gear, a ring gear, and carrier and planetary gears, can minimize the power to the CVU. However, a SPCVT with a conventional CVT should possess a dual mode, which would allow the conventional CVT to be used at high speeds and an additional gear train to be used at low speeds. The inner-spherical CVU(ISCVU) with an inner and outer spherical contact mechanism developed in this study can cover the range from low to high speeds. The rated power and the overall speed ratios were 100 kW and $0.09{\sim}0.36$, respectively. Power efficiency was numerically calculated to be over 90% over the speed ratio range of $0.1{\sim}0.29$. The maximum shear stress at the two contact areas of the rotor pairs, the minimum life and the overall size were estimated to be 700 MPa, 276 kh and $350{\times}350{\times}400mm^3$, respectively. This study shows that an ISCVU and a variable bridge type PGU can realize the SPCVT with a single mode for a vehicle.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.3
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• pp.654-662
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• 1998

Shift quality of an automatic transmission in a vehicle is mainly affected by transient pressures in the hydraulic system during shifting. In this study, dynamic modelings of the hydraulic system and the power train of an automatic transmission are made systematically by a bond-graph method. The dynamic characteristics of the line pressures and clutch/brake pressures during shiftings are investigated by simulations and verified by experiments. The effects of clutch/brake pressures on the shift torque are also investigated through driving simulation.