What is the function of coupler buffer device?

Coupler buffer device is a vehicle component used to connect vehicles with vehicles, locomotives or motor trains, transfer traction and braking force, and mitigate longitudinal impact force. It is composed of coupler, bumper, coupler tail frame, slave plate and so on, and is installed in the traction beam at the end of the underframe. In order to ensure the safety and reliability of vehicle coupling and the interchangeability of coupler buffer installation, the relevant regulations of railway rolling stock in China stipulate that the height between the horizontal center line of coupler tongue and rail surface after the coupler buffer is loaded is 88mm (allowable +1mm, -5mm error) for passenger cars and 88 mm (1 mm) for freight cars. The maximum height difference between the horizontal center lines of couplers of two adjacent vehicles shall not be greater than 75 mm.

first of all, talk about couplers. Coupler is a vehicle component used to realize the connection between locomotive and vehicle or between vehicles, transmit traction and impact force, and keep a certain distance between vehicles. Couplers are divided into two types according to the opening mode: upper acting type and lower acting type. The lifting mechanism at the upper part of the coupler head is called the up-acting type (this type is mostly used in general freight cars); Push-down action type (adopted by passenger cars) to realize opening by the action of pushing lever at the lower part of hook head. Couplers are divided into spiral couplers, close-fitting automatic couplers, automatic couplers and rotary couplers according to their structural types. Spiral couplers were first used, but they have been eliminated due to many shortcomings. Close-fitting automatic couplers are mostly used by high-speed railway vehicles. In China, automatic couplers are all used except rotary couplers on heavy-haul unit trains of Daqin Railway. The so-called automatic coupler is a coupler that can automatically unhook or hook when the lift lever of a coupler is lifted first, and then the locomotive is used to pull the vehicle away or collide with the coupler of another vehicle. In 1956, China Railway Department determined that No.1 and No.2 couplers were standard couplers. However, with the increase of train speed and traction tonnage, No.15 coupler and No.13 coupler were designed and manufactured successively in 1957 and 1965. Passenger cars use No.15 coupler, while freight cars gradually replace No.2 coupler with No.13 coupler.

the coupler consists of three parts: the coupler head, the coupler body and the coupler tail. The thick part at the front end of the coupler is called the coupler head, and the coupler head is internally provided with a coupler tongue, a coupler tongue pin, a locking pin, a coupler tongue pusher and a coupler lock iron. The rear part of the coupler is called the coupler tail, and there is a vertical flat keyhole on the coupler tail to connect with the coupler tail frame. In order to connect or disconnect the vehicle, the coupler has the following three positions, that is, the three states of the coupler: the locking position-the position where the coupler tongue is blocked by the coupler lock iron and cannot be turned outward. The coupler is in this position when two vehicles are linked together. Unlocking position-that is, the position where the hook lock iron is lifted and the hook tongue can be turned outward as long as it is pulled. When unhooking, as long as one coupler is in the unlocking position, two cars linked together can be separated. Full open position-that is, the position where the hook tongue has been completely turned outward. When two cars need to be linked, as long as one coupler is in the full open position, it can be linked after colliding with another coupler. The structure of the rotary coupler is different from that of the ordinary coupler, the coupler tail is provided with a lock hole, and the coupler tail pin is connected with the rotating sleeve of the coupler tail frame. The tail end surface of the hook is a spherical surface, which abuts against the front slave plate with concave spherical surface. When the hook head is subjected to torsional moment, the hook body rotates together with the tail pin and the rotating sleeve. The rotary coupler is now only installed on the vehicles specially designed for the combined train of coal transport unit of Daqin Railway. One end of this vehicle is equipped with a rotating coupler, and the other end is equipped with a fixed coupler. The two couplers connected in each group on the whole train are matched with each other. When a vehicle loaded with coal enters the dumper in the coal unloading area, the dumper drives the vehicle to turn over 18 degrees to dump the coal. Rotating the coupler can make the vehicle work continuously when it is overturned and unloaded, thus shortening the unloading operation time. Close-fitting couplers are generally used on vehicles of high-speed railway and underground railway. It is small in size and light in weight, and the relative movement in all directions after two couplers are connected is very small, which can realize real "tight connection"; At the same time, it is very beneficial to improve the reliability of automatic docking of brake hose and electrical connector.

The buffer is used to alleviate the longitudinal impact and vibration caused by the change of locomotive traction or the collision of vehicles during starting, braking and shunting operations. The buffer has the function of dissipating the impact and vibration between vehicles, thus reducing the damage to the car body structure and loaded goods. The working principle of the buffer is to relieve the impact force by compressing the elastic element, and at the same time, to absorb the impact energy by friction and damping during the deformation of the elastic element. According to the structural characteristics and working principle of buffers, general buffers can be divided into friction buffers, rubber buffers and hydraulic buffers. The friction buffer consists of a front part and a back part. The front part is a spiral spring (for passenger cars) or a ring spring (for freight cars), and the back part is an inner ring spring and an outer ring spring, which are matched with each other by a conical surface, and the two parts are separated by a spring seat plate. The spiral spring is used to alleviate the impact force, and the friction between the two sliding slopes of the ring spring is used to absorb energy. When the buffer is compressed, the rings are pressed against each other, and most of the impact energy is stored in the outer ring spring. At the same time, part of the impact energy is changed into heat energy due to mutual friction between the inclined planes of the inner and outer ring springs. When the external force is removed, friction occurs between the ring springs again, and part of the stored energy is converted into frictional heat energy and dissipated again, thus playing a role in buffering and vibration reduction. The head of the rubber bumper is a wedge friction part, which consists of three wedges with the same shape and inclination angle, a pressure head and a box, etc. The wedge is between the pressure head and the box, and the whole bumper is enclosed in the box. The rubber bumper plays a role in mitigating impact and consuming energy by means of internal friction and elastic deformation of rubber molecules. In order to increase the capacity of the buffer, a metal friction part is installed in the head, and with the help of three wedges with inclination angles, it will generate relative displacement with each contact inclined plane between the box body and the pressure head when pressed, and the impact energy will be consumed due to friction.