A differential is a mechanical device that supports smooth driving, by allowing each of the two wheels, to rotate at differential speeds during a turn. This is particularly crucial for tractors, as they mainly work on the ground, often becoming stuck off-highway, or falling into pits. When the tractor wheel is stuck off-highway, it is difficult to get the wheel out, as the differential of the tractor reduces friction between the wheel and the ground surface. In order to prevent this wheel slip situation, the differential locking device, which restricts the two wheels on the axle to the same rotational speed, has been used in the axle of the tractor. In this study, analysis models of the hydraulic system and the dog clutch were developed to predict the performance of the differential locking device. Using the LMS imagine. AMEsim software, the analysis models were verified by comparing the simulation results with the experimental data. Using the models developed, the influence of the release time of the differential locking device on selected design parameters was analyzed, to determine the effect on the release time of the differential locking device. As a result, design values that will improve the performance of the differential locking device were derived.

The planetary geartrain can be reduced in size and weight, and has excellent durability since the input torque is divided by the number of planet gears when the power is transmitted. In order to improve its durability, the load sharing among planet gears must be even. However, of the various manufacturing errors possible, the carrier pinhole position error has the greatest influence on load sharing. This study compared and analyzed the load sharing and the gear safety of planetary gears, according to the phase of the carrier pinhole position error. We confirmed that load sharing among the planet gears varied, depending on the phase of the carrier pinhole position error. The mesh load factor is inversely related to the gear safety factor for bending and contact, and affects the durability of the planetary geartrain. Also, in the design of the planetary geartrain, the load sharing among planet gears is directly affected by the carrier pinhole position error and its phase. Therefore, the geometric tolerance must be managed efficiently, which needs to be reflected in the production drawings.

A loader used for uploading materials into truck is a kind of construction equipment. Mainly, a wheel loader is applied to construction work. Recently, an automatic transmission for the wheel loader is used to help drivers get the repetitive works done comfortably. It is composed of geartrain, clutch pack, hydraulic control system and TCU. Especially, a high-performance proportional control valve and its control algorithm is demanded to achieve the shift quality during a change of speed. In this paper, the commercial package program was used in order to justify model of the proportional control valve and simulate it. Steady-state and dynamic characteristics of PCV were analyzed to classify attractive forces and hydraulic control characteristics. This model also was verified the validity compared to the experimental result. Using the developed model, performances of PCV were predicted as studying design parameters.

The automated mechanical transmission(AMT) is composed of electronic control management (ECM) and automatic shift gear(ASG). The AMT has advantages which are high efficiency of manual transmissions(MT) and offer operation convenience similar to automatic transmissions (AT). However, it has defects that are the torque gap during gear shift transients and shift time is long. To reduce such defects, it is necessary practically to evaluate error and characteristics as developing simulation model before the control algorithm is applied. In this paper, models are composed of vehicle model and AMT shift control model. Particularly AMT shift control model consists of main clutch management model (MCM) and shift control management model(SCM). The developed models were verified by comparing the simulated and experimental results under the same operational conditions. It can also be used to evaluate shift algorithm.

An automatic transmission of construction equipment is controlled by hydraulic and electronic system for doing in various functions like as shifting and operation. The shifting is operated by the engaged and disengaged clutch motion from hydraulic power On the shifting process, suitable pressure control to the clutch is required for smooth shifting. Hydraulic control system in the automatic transmission is divided by the pilot control type and the direct control type greatly. The direct control type has an advantage than the pilot control type. Because the structure is simple, the design and the manufacture are having less troubles and the system can be maximized precision pressure control. However, the excellent performance proportional control valve should be used to achieve proper control-ability. In this study, the dynamic analysis model composing the automatic transmission and hydraulic system for forklift truck is presented to simulate the characteristics of hydraulic system about the direct control type. That model is verified the validity compared the results of the testing examination. Parameters of input signal are analyzed to reduce the output torque according to input control signal is affected in shifting characteristic.