Numerical analysis has been performed to investigate the stress distribution characteristics of auxiliary axle system in a compact special vehicle. Structural and running stability of compact special vehicle is largely affected by auxiliary axle system installation. Structural characteristics of stress and deformation distributions with safe factor in the auxiliary axle system are analyzed. It can be seen that maximum stress happens near the local axle position, and deformation is also predicted. Simulation results are also compared with experimental test data. These results from this study could be applicable for optimal design of diverse axle systems in the compact special vehicle.

Numerical analysis has been carried out to investigate the structural characteristics of auxiliary shaft system in a compact special vehicle. Stress and deformation distributions with safe factor in the auxiliary axle system are compared. It can be seen that maximum stress happens near the local axle position and deformation at the air spring is also predicted. The results from this study could be applicable for optimal design of variable shaft system in the compact special vehicle.

Experimental analysis has been carried out to investigate oil temperature control characteristics of the hydraulic system in a special vehicle. Hydraulic system performance is largely affected by oil temperature, and there are considerable malfunctions in the system for high temperature conditions caused by heavy load and continuous operation. Oil pressure in the hydraulic system decreases with oil temperature, and its variation rate becomes less steep as oil temperature increases. There is severe time delay for oil temperature control due to the operation of heat exchanger system, and it depends on the oil flow rate and pressure in the system. These results in this study can be applied to the design of automatic thermal control system in the special vehicle hydraulic system.

Experimental analysis has been carried out to investigate thermal characteristics of hydraulic system in special vehicles. Hydraulic system performance is largely influenced by oil temperature, and there are considerable performance decline and malfunctions in the system for high temperature conditions caused by heavy load and continuous operation. Transient oil temperature and pressure variation are analyzed and heat generation rates in the several main system parts are compared for various flow rates. With the start of system operation oil temperature gradually increases, and viscosity deceases by about 70% as temperature increases from 20℃ to 80℃. Operation pressure in the hydraulic system decreases with oil temperature, and its variation rate becomes less steep as oil temperature increases. Heat generation rate in hydraulic pump also depends on the oil temperature, and it reaches maximum near 50℃. These results in this study can be applied to optimal design of efficient hydraulic system in special vehicles.