• 한국생산제조학회지
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• 제18권6호
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• pp.565-575
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• 2009

A forklift (also called a lift truck) is a powered industrial truck that is used to lift and transport materials. It has become an indispensable piece of equipment in manufacturing and warehousing operations. The modem forklift is equipped with automatic transmission to meet the requirement of loading and easy operation of the vehicle. This paper proposes the design of TECU(Transmission Electronic Control Unit) which is applied to PSD322-Axle transmission. Garofalo's control technique is generally used to the automatic transmission. We consider the work quality and market requirement that does not want to control engine throttle. This paper proposes new controller system which guarantees efficient speed changes with simple system. This new system does not control the engine throttle spontaneously. But it has the load of engine and vehicle as a maximum disturbance. The scope of the disturbance is limited to the stoll area of the torque converter. This paper proposes a ideal control commander that converges relative velocity of the input and ouput of a clutch into a zero. We design linear controller to execute the idea control commander. We applied the control algorithm to the forklift of PSD322-Axle type and the performance of this controller was verified.

• International Journal of Automotive Technology
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• 제6권3호
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• pp.221-227
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• 2005

Aim of this study is to investigate an aerodynamic effect of a drag-reducing device on a heavy-duty truck. The vehicle experiences two different kinds of aerodynamic forces such as drag and uplifting force (or downward force) as it is traveling straight forward at constant speed. The drag force on a vehicle may cause an increase of the rate of fuel consumption and driving instability. The rolling resistance of the vehicle may be increased as result of the negative uplifting or downward force on the vehicle. A device named roof-fairing system has been applied to examine the reduction of aerodynamic drag force on a heavy-duty truck. As for a engineering design information, the drag-reducing system should be studied theoretically and experimentally for the best efficiency of the device. Four different types of roof-fairing model were considered in this study to investigate the aerodynamic effect on a model truck. The drag and downward force generated by vehicle has been obtained from numerical calculation conducted in this study. The forces produced on four fairing models considered in this study has been compared each other to evaluate the best fairing model in terms of aerodynamic performance. The result shows that the roof-fairing mounted truck has bigger negative uplifting or downward force than that of non-mounted truck in all speed ranges, and drag force on roof-fairing mounted truck has smaller than that of non-mounted truck. The drag coefficient $(C_D)$ of the roof-fairing mounted truck (Model-3) is reduced up to $41.3\%$ than that of non-mounted trucks (Model-1). A downward force generated by a roof-fairing mounted on a truck is linearly proportional to the rolling resistance force. Therefore, the negative lifting force on a heavy-duty truck is another important factor in aerodynamic design parameter and should be considered in the design of a drag-reducing device of a tractor-trailer. According to the numerical result obtained from present study, the drag force produced by the model-3 has the smallest of all in all speed ranges and has reasonable downward force. The smaller drag force on model-3 with 2/3h in height may results of smallest thickness of boundary layer generated on the topside of the container and the lowest intensity of turbulent kinetic energy occurs at the rear side of the container.

• 한국정밀공학회지
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• 제28권11호
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• pp.1309-1315
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• 2011

The design process for obtaining the reliable steeraxle casting beam of fork lift truck is studied in this paper, as the casting beam is major component of steeraxle which has a steering function at driving. In this study, the driving mode and damage pattern of casting beam which could be occurred from the customer site were analyzed and it established the design process to predict the fatigue life by FEA(Finite Element Analysis) so that the reliability of steeraxle casting beam could be verified at DVT(Design Validation Test) mode. This paper provides guidance on the process of designing the reliable steeraxle casting beam at the initial design stage and also, provides guidance on the process of solving the problem when the failure is occurred in the field.

• 한국자동차공학회논문집
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• 제14권2호
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• pp.194-201
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• 2006

Roof-fairing and deflector system have been used on heavy-duty trucks to minimize aerodynamic drag force not only for driving stability of the truck but also for energy saving by reducing the required driving power of the vehicle. In this study, a numerical simulation was carried out to see aerodynamic effect of the drag reducing device on the model vehicle. Drag and lift force generated on the five different models of the drag reducing system were calculated and compared them each other to see which type of device is efficient on the reduction of driving power of the vehicles quantitatively. An experiment has been done to see airflow characteristics on the model vehicles. Airflow patterns around the model vehicles were visualized by smoke generation method to compare the complexity of airflow around drag reducing device. From the results, the deflector systems(Model 5,6) were revealed as a better device for reduction of aerodynamic drag than the roof-fairing systems(Model 2,3,4) on the heavy-duty truck and it can be expected that over 10% of brake power of an engine can be saved on a tractor-trailer by the aerodynamic drag reducing device at normal speed range($80km/h{\sim}$).

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1997년도 춘계학술대회논문집; 경주코오롱호텔; 22-23 May 1997
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• pp.557-563
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• 1997

In order to satisfy the regulations concerned with the noise emission of fork-lift trucks and thereby increase export to the western countries, a noise reduction technique should be developed in the early design stage. In this paper, several noise sources are identified using the sound suppression method and sound intensity measurement, and their contributions to the sound levels at the operator's ears and at the distance of 7m from the vehicle are studied. For each of the major noise producting components, noise abatement alternative are suggested and their effects are analyzed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1995년도 추계학술대회논문집; 한국종합전시장, 24 Nov. 1995
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• pp.99-103
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• 1995

소음저감 설계기술은 제품의 경쟁력 향상을 위해 자동차, 항공기, 건설 장비, 선박, 심지어 가전 제품에 있어서도 소음 문제에 대한 관심이 크게 대두되고 있다. 특히 수출을 하기 위해서는 그 지역의 소음 규제법을 만족시켜야 하며 제품의 경쟁력을 위해서는 그 이상의 것이 요구되고 있다. 또한, 소음 문제는 소비자의 제품구매 선택에 영향을 주기도 한다. 일본의 경우 JIS 규격으로 건설 장비의 소음을 규제하고 있으며, 소음수준에 따라 일반 장비, 저 소음 장비, 초 저소음 장비로 구분하여 장비에 따라 건설 작업을 제한하기도 하며, 특히 초 저소음 장비 인증을 받은 것은 장비 사용 단가 및 사용에 있어 차등을 두어 혜택을 주고 있다. 본 논문에서는 현재 구미지역에서 소음규제로 사용되는 BITA 방식에 따라 지게차의 소음원 규명 및 소음 저감 대책을 논하고자 한다.

• 한국기계가공학회지
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• 제17권2호
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• pp.124-129
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• 2018

A forklift is used to lift materials above a height of 2 m. The width of the fork determines the weight of the material it can carry. In this paper, three models of fractured forklifts were analyzed to determine if the fracture was caused by load fatigue due to the width of the fork. The position of the fork was fixed on each model, and a 2.5 ton load was placed at the upper part of the fork. The width distances on each of three models were 500 mm, 750 mm and 1000 mm, and the maximum equivalent stresses were 237.5MPa, 227.62MPa and 230.99MPa, respectively. This analysis demonstrated that as the load increased with use of the wider fork, the fatigue life remained to be nearly equivalent irrespective of fork width among all three models. The results of this study contribute to the durability and safety design of forklifts.

• International Journal of Railway
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• 제3권2호
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• pp.60-67
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• 2010

This paper deals with an experimental study on the wheel flange climbing of railway vehicles, which is a major factor leading to derailment. An experiment is carried out on a 1/5-scale model wheelset of a truck used on a standard-gauge track, which is placed on a roller rig. The lateral external force acting on the wheelset is ramped up until derailment occurs under the condition of a fixed attack angle and wheel-load unbalance ratio. Three parameters, the height of wheel lift, the lateral force, and the wheel load acting on the outer rail, are measured until derailment occurs. From these measurements, it is possible to observe the behavior of the wheelset and to elucidate how the attack angle, the wheel-load unbalance ratio and the lateral external force affect flange-climb derailment. Then, a numerical simulation is carried out using an analytical model based on a single wheelset. As a result, the flange-climb behavior observed in the experiment can be explained theoretically on the bases of the analytical results, although further improvement of the model is desired.

• 한국지진공학회논문집
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• 제10권6호
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• pp.1-8
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• 2006

본 논문에서는 교량 모니터링 시스템의 일부분으로 서해대교에 설치된 교량 하중측정 시스템(BWIM system)으로부터 획득한 신호를 분석하여 통행차량의 정보를 추출하기 위한 알고리즘의 개발과정과 이를 위해 수행한 현장 차량주행시험에 대하여 기술하였다. 개발된 BWIM 시스템은 포장층에 매설하는 축감지기가 없는 형태로, 바닥판과 가로보에 설치된 변형률계로부터 측정한 시간이력 변형률신호만을 이용하였다. 이들 측정신호로부터 추출하고자 하는 차량의 정보는 통과차로, 통과속도, 차 축수 및 총 중량이며, 이들 정보의 추출을 위해 패턴인식기법의 일종인 인공신경망(Aritificial Neural Network, ANN) 기법을 사용하였다. 현장 차량주행시험을 통하여 기지차량 및 미지차량 통행시의 BWIM 응답 데이터를 측정하였으며, 이들 실측데이터를 사용하여 인공신경망의 학습 및 성능검증을 수행하였다. 개발된 기법을 사용하여 추출되는 차량의 정보들은 현재의 교량상태 및 피로수명 평가시 활용될 수 있을 것이며, 향후 설계트럭 하중모델의 개정시 기초자료로도 활용될 수 있을 것으로 기대된다.

• 한국산학기술학회논문지
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• 제11권11호
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• pp.4100-4107
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• 2010

사고 현장에서 사고 차량을 옮기거나 주차위반 차량을 견인사업소로 이동시키기 위해 주로 이용되고 있는 리프트식 견인차는 피견인차의 구동방식에 따라 차량의 전부 또는 후부을 들어 올려 구동 바퀴로 이동할 수 있도록 하는 특수차량이다. 각 차량은 CATIA를 이용하여 모델링하고 이를 상용 유한요소해석 프로그램인 ANSYS를 통하여 피견인차의 후부를 주행 차량이 들이 받는 추돌을 시뮬레이션한다. 본 논문에서는 견인중인 견인차와 이송중인 전륜 피견인차 및 일반 주행 중인 차량 사이에서 일어날 수 있는 3중 추돌사고를 일반적인 3중 추돌사고와 비교하여 견인중에 발생하는 추돌사고가 얼마나 위험한지를 직접 확인한다. 또한 견인차가 피견인차를 들어 올려 발생되는 피견인차의 각도에 따른 추돌의 영향을 해석한다.