• Transactions of the Korean Society of Automotive Engineers
• /
• v.7 no.8
• /
• pp.216-223
• /
• 1999

This study was intended to determine the inertia , damping and stiffness properties of the cab-suspension of agricultural tractors by applying the direct system identification method (DSIM). Since the rigid and elastic modes of the cab-suspension are not likely to be separated clearly, direct application of the DSIM may result in large computation error. To solve such a problem, a method of locating mass center of the cab were determined by assuming the behavior of the cab-suspension is a rigid body motion. The dynamic parameters of the cab-suspension were then determined by applying the DSIM with the known coordinates of the mass center. The constraints of spatial matrices of the cab-suspension also make the algorithm for the DSIM perform better. The values of dynamic parameters determined by this method agreed well with those determined by the experiment.

• Journal of Biosystems Engineering
• /
• v.23 no.4
• /
• pp.327-334
• /
• 1998

This work was intended to determine the optimum values of the cab suspension parameters by a simulation method in order to minimize the seat accelerations of agricultural tractors in the frequencies lower than 50Hz. A dynamic model of cab motions was developed and verified using a tractor excited over half-sine bumps on a concrete test road. A simulation program based on the model was also developed. A method was proposed to determine the optimum values of the suspension parameters. It was found that the natural frequencies of the cab and seat suspensions must be apart as far as possible until the sum of seat and cab accelerations is minimized, which also reduces the seat accelerations maximally.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2014.10a
• /
• pp.472-475
• /
• 2014

Abnormal cab vibrations in the Y direction in commercial vehicles during driving(70~90kph) are not common vibrations that happen to vehicles during driving and can be an obstacle to normal driving. This study conducted Operation Deflection Shape(ODS) testing to identify the causes of those abnormal cab vibrations and find solutions for them and also a sine sweep test to find resonance and frequency in the cab suspension system and set directions for improvement. The study also altered the shape of the bush inner part for changes to the rigidity features of the cab bush in the Y direction and revised the design with optimal rigidity in the Y direction, thus improving abnormal cab vibrations in the Y direction during driving.

• Journal of Biosystems Engineering
• /
• v.20 no.2
• /
• pp.127-132
• /
• 1995

In the first part of this paper, an analysis of the cab noise of a selected agricultural tractor was presented. In this study, using the results of the previous analysis, two passive noise control measures of the sound insulation and absorption were conducted to reduce the noise level inside the cab. These measures of noise control reduced the total noise level by 6.2㏈(A) at the operator position inside the cab. In order to further reduce the cab noise, particularly, of lower frequencies than 630Hz, stiffness and damping of the floor panel should be enforced. It was also suggested that a proper suspension for the cab mounting is necessary to reduce the level of structure-born noises.

• Journal of Biosystems Engineering
• /
• v.26 no.3
• /
• pp.237-244
• /
• 2001

This work was intended to investigate the effect of vibration transmission paths on the ride vibration of tractor during the rotavating and transporting operations by applying the vibration path analysis method. Accelerations at the cab mounts were measured during the rotavating and transporting operations. Ride vibrations at the sear were than calculated using the measured accelerations at the cab mounts, and the frequency response functions and inertances between the seat and cab mounts, which were derived experimentally by the impact hammer test in static condition. The human sensitivity to vibration frequency was also taken into consideration for the calculation of ride vibrations at the 1/3 octave center frequencies in the frequency domain. Vibrations transmitted through rear cab mounts affected more significantly the ride vibration of tractor. The peak accelerations at the seat occurred at the frequencies of the engine and crank speed, and the frequency induced by tire lugs on the road transportation. It was found that the rear cab mounts should be improved in order to reduce the ride vibrations more effectively.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 2000.02a
• /
• pp.10-15
• /
• 2000

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 1998.12a
• /
• pp.16-22
• /
• 1998

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.871-876
• /
• 2005

Currently, the marketable truck has the cab tilting system which highly absorb the vibrations and impacts of cab. The cab tilting system is equipped with the hydraulic system for maintenance and inspection of truck. And it is very important to improve the user's feeling of driving and convenience. To have the better performance, it is important to confirm the dynamic characteristics of each parts of the system. In this study, a mathematical model of the system was derived and the parameters in the model were identified from experimental data. The results of the simulation were compared with those of experiments. These results of the computer simulation and experiments show that the proposed analysis can be applied effectively to design the system. Our results can be utilized for the future research to improve the capability of the truck cab tilting system.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 1999.12a
• /
• pp.85-91
• /
• 1999

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.29 no.2 s.233
• /
• pp.270-276
• /
• 2005

This paper develops the flexible computational model of a heavy truck by interfacing the frame modeled as a flexible body to the heavy truck's computational model composed of rigid bodies. The frame is modeled by the finite element method. Three torsional modes and three bending modes of the frame are considered for the interface of the heavy truck's computational model. The actual vehicle test is conducted off road with a velocity of 20km/h. The vertical accelerations at the cab and front axle are measured in the test. For the verification of the developed computational model, the measured vertical acceleration profiles are compared with the simulation results of the heavy truck's flexible computational model. E grade irregular road profile of ISO is used as an excitation input in the simulation. The verified flexible computational model is used to compare the vibration characteristics of a front suspension system having a multi-leaf spring and that having a tapered leaf spring. The comparison results show that the front suspension having a tapered leaf spring has a higher vertical acceleration at the front axle but a lower vertical acceleration at the cab than the suspension system having a multi-leaf spring.