Spatial Kinematic Analysis of a Tracked Forest Fire Engine with Fish-Bellied Swing Arm Torsion Bar Suspension

Abstract

To decrease track derailment of tracked fire trucks in forested areas, a fish-bellied swing arm torsion bar suspension system is proposed in this research. Derived from a tracked forest fire engine, this study converts the shaft tube swing arm of the original vehicle to a fish-bellied swing arm, improving the semi-rigid shaft tube suspension to a torsion bar suspension. Static and kinematic simulation analysis of the improved virtual sample vehicle is carried out, and the stress and dynamic characteristics before and after the improvement are analyzed. The simulation force cloud diagram of the improved swing arm and the motion simulation curve of the supporting wheel is obtained. The results show that the design of the fish-bellied swing arm can effectively reduce the bending moment caused by force acting on the swing arm, and that the design of the torsion bar spring suspension can reduce vertical displacement of the supporting wheel by 58.53%, and reduces horizontal displacement by 46.58% under the same impact force. According to the design of the virtual sample to build a prototype vehicle, a comparative test is carried out to determine an optimized virtual sample vehicle. The results show that the trend of the test curve is essentially consistent with that of the simulation curve.

Keywords

• torsion bar suspension chassis
• fish-bellied swing arm
• kinematic model
• virtual simulation
• tracked fire engine