Abstract:  Aiming at the problems of low braking efficiency and great impact of over delivery pick-up vehicle in the stereo garage,a variable throttle hydraulic braking system for the over delivery pick-up vehicle was designed and proposed. Firstly, the working principle of the variable throttle hydraulic braking system was explained, the mathematical model of the braking process was established. Then the linear and nonlinear relationship between the crane plate brake displacement and the variable throttle valve opening was designed. Finally, based on AMESim, the simulation model of the variable throttle hydraulic braking system was built. The braking characteristics of the variable throttle braking system of over delivery pick-up vehicle were analyzed. The braking efficiency of variable throttle braking system was calculated. The influence of three kinds of variable throttle valve opening control functions on the braking effect of the system was studied. The results show that there is no pressure impact in the braking process of the variable throttle hydraulic braking system. The braking efficiency of the system can reach more than 99%. The crane plate brake displacement is completely determined by the variable throttle valve opening control function. The crane plate displacement response increases with the increase of over discharge mass. With the increase of over discharge speed, the peak pressure of the brake chamber increases obviously.

Key words:  stereo garage; over delivery pickup vehicle; variable throttle; braking efficiency; valve opening function; braking displacement