Abstract
KEYWORDS:
road vehicle, forklift, dynamical model, mathematical model, overturning stability
ABSTRACT:
Forklift truck (lift truck) is a special vehicles equipped with frontal forks for lifting materials (palettizated or packed). The forklift truck is representative of vehicles designed to carry outside of their wheelbases. During the transportation of the materials on the loaded fork, various exterior forces act on the vehicle, being able to affect the overturning stability in certain work conditions.
The paper presents the equivalent dynamical model of the forklift truck, specifying the exterior forces acting in the most difficult work situations: descending on a slope, braking of the vehicle in translatory motion, acceleration of the fork while lifting the load. Based on the equivalent dynamical model, are elaborated the mathematical models describing the dynamical behavior of the forklift truck during moving or working. These models deliver the criteria for the overturning longitudinal stability.
The computer aided solving (simulation) of the mathematical models allows the analysis of the longitudinal stability of the fork lift truck and the variation of the rear axle loads of the truck and implicitly the dynamic and static longitudinal stability of the fork lift truck depending on the values of the descended slope tilt angle, the translator braking decelerations of the vehicle and of the braking decelerations of the load, considering the fork carrying various loads and raised to various heights.
The analysis of the dynamic and static longitudinal stability of the system was performed by applying similar methods used for lifting equipment and by using the concept of stability factor or overturning safety factor. This is defined by the ratio of the stability moment and the overturning moment of the system related to the overturning line (the line running through the supporting points on the road surface of the front wheels).By computer simulation of the mathematical models the longitudinal stability of the forklift truck is analyzed with application for a constructive model of fork lift truck.