Buffer is one of the important parts of rail transit vehicles. Its function is to alleviate the longitudinal impulse and vibration caused by the change of locomotive traction or the collision between vehicles during starting, braking and shunting. It directly affects the total traction weight, running speed, total weight of vehicles Marshalling operation efficiency and other main technical and economic indicators related to railway transportation efficiency. The performance of buffer directly affects the driving safety and passenger comfort. Therefore, countries all over the world pay attention to the development and research of buffer with excellent performance.

At present, the typical buffers in China include grease lubricated ring spring friction buffer and hydraulic buffer, but they are difficult to be widely popularized because of their poor low-temperature performance and aging resistance, short service life, complex manufacturing and maintenance process, high cost, self weight and high requirements for manufacturing and processing accuracy.

The buffers of passenger cars in China are basically of ring spring structure with grease lubrication. The buffers of ring spring structure can not meet the performance requirements of Speed-up Passenger Cars, mainly in the following aspects:

① If the initial pressure is too large, the initial pressure can reach more than 100kN;

② Just too large, few buffers play the role of buffer in 20 car passenger trains, and the available energy of buffer is very small;

③ The absorption rate is small. The drop weight test shows that the absorption rate of G1 buffer is small, which is easy to cause continuous longitudinal impulse of the train;

④ The maintenance cycle is short. Because G1 buffer is lubricated with grease, the validity period of grease is short. The failure of grease may cause the problems of snap ring, ring damage and ring breakage, which must be repaired regularly.

1、 Introduction to elastic mastic buffer

The buffer medium elastic mastic material used for the research of elastic mastic buffer is a kind of unvulcanized silicone compound with high viscosity, compressibility and flowability. It has high stability in the range of - 80 ~ + 250 ℃, and is odorless, non-toxic and pollution-free to the environment and personnel. It has two states of solid and liquid. It is an ideal buffer medium material for coupler buffer. Without the action of restoring spring, the restoring return of buffer can be realized by using its high elasticity; Using its compressibility to realize the compression stroke of the buffer; Using its good fluidity can realize the large capacity and low impedance of the buffer. The flow viscosity of this material can be adjusted according to the needs of actual use, and its kinematic viscosity can be dozens or even hundreds of times larger than that of ordinary hydraulic oil. In this way, the problem of difficult sealing of hydraulic buffer is simplified. If this material can solve the production process problems, its cost will not be higher than $60 / kg, and the amount of elastic mastic will not exceed 3kg when the capacity of an elastic mastic buffer is 15kj. Therefore, the price of elastic mastic material can meet the market requirements for the promotion of elastic mastic buffer.

2、 Basic structure principle of elastic mastic buffer

The elastic mastic buffer is mainly composed of piston, piston rod, cylinder head, cylinder block, charging valve, etc. (see Figure 1). Its working principle is: put the elastic mastic material into the buffer and apply a certain pre pressure as required. When the buffer piston rod is under a certain pressure, the elastic mastic is compressed to produce impedance force, The throttling effect of the annular gap (or orifice) of the piston and the compression deformation of the elastic mastic material are used to absorb the impact energy. Due to the characteristics of the mastic material, the greater the pre pressure of the elastic mastic and the movement speed of the piston, the greater the impedance, which is conducive to improving the capacity of the buffer under large impact, that is, the greater the impact, the greater the capacity of the buffer; The smaller the impact, the smaller the capacity of the buffer. When the external force acting on the piston rod is cancelled, the elastic mastic expands by itself and pushes the piston back to the original position. In this process, the elastic mastic material flows back to the original position through the annular gap (or orifice) of the piston at a slow speed to realize the return action of the buffer