RELIABILITY ANALYSIS OF CRANE BRAKE PARAMETERS

The high failure rate of crane brake results from improper choice of brakingtorque. The mathematical model of reliability for the crane brake parameters is introduced. Based onlarge amount of actual data the parameter reliabilities of 5 approx 50 t general overheadtravelling cranes are calculated, the probabilities that the braking torque is less than the statictorque acting on the axle when the load moves down are obtained. Moreover, the ways to improve thereliability of brake parameters are discussed, the most reasonable values of braking safetycoefficient are given.

Research of Energy Regeneration Technology in Electric Vehicle

The theory of energy regeneration in electric vehicle (EV) has been introduced in most papers, but the mathematic model of EV energy regeneration system was little studied. In this paper the mathematic model of EV energy regeneration system is studied, and then the system ability under four control strategies is analyzed. In the end the system reliability is researched, and the calculation model of system reliability is proposed.

Gear walk instability caused by brake-disc friction characteristics

A multi-body dynamic rigid-flexible coupling model of landing gear is established to study the gear walk instability caused by the friction characteristics of the brake disc.After validating the model with the experimental results,the influence of the landing gear structure and braking system parameters on gear walk is further investigated.Among the above factors,the slope of the graph for the friction coefficient of the brake disc and the relative velocity of brake stators and rotors is the most influential factor on gear walk instability.Phase trajectory analysis verifies that gear walk occurs when the coupling of multiple factors causes the system to exhibit an equivalent negative damping trend.To consider a more realistic braking case,a back propagation neural network method is employed to describe the nonlinear behavior of the friction coefficient of the brake disc.With the realistic nonlinear model of the friction coefficient,the maximum error in predicting the braking torque is less than 10%and the effect of the brake disc temperature on gear walk is performed.The results reveal that a more negative friction slope may contribute to a more severe unstable gear walk,and reducing the braking pressure is an effective approach to avoid gear walk,which provides help for future braking system design.

Experimental and Internal Flow Investigation on the Performance of a Hydraulic Retarder with Different Liquid-Filled Amount and Blade Inclination Angles

In order to study the variation of brake torque,vibration,pressure fluctuation,exterior noise and internal flow for a hydraulic retarder with different inclination angles and liquid-filled amount,a bench-scale hydraulic retarder was built.The INV3020 data collection system was used for the synchronous acquisition of brake torque,vibration,pressure fluctuation and exterior noise signals.Experiments were performed with different inclination angles(90°and 75°)and six liquid-filled amount(50 vol%,60 vol%,70 vol%,80 vol%,90vol%and 100 vol%).The torque-volume ratio was proposed to accurately analyze the influence of inclination angle on the liquid volume in stator and rotor and the brake performance.Mixture multiphase flow model was employed to capture the volume and velocity distribution.The research shows that the brake performance improves and the vibration increases with the decrease of inclination angle and the increase of liquid-filled amount.The pressure fluctuation increases as the liquid-filled amount increases,while the lower inclination angle effectively lowers the pressure fluctuation amplitude.The sound pressure level trends upward with increasing liquid-filled amount,and the lower inclination angle can effectively reduce the noise.The volume distribution of the liquid phase under different liquid-filled amount is basically consistent.The lower inclination angle can induce more vortexes.