Unlock high-speed EMU bogie technology: From design to performance

The bogie is one of the most important components of a locomotive. Whether its structure is reasonable directly affects the running quality, power performance and driving safety of the locomotive. The rapid running of high-speed trains around the world and the rapid development of modern urban rail vehicles are closely related to the progress and development of bogie technology. It is no exaggeration to say that bogie technology is one of the core technologies for the survival and development of “modern locomotives driven by wheel-rail contact.” Due to the differences in the history and background of railway development in various countries, as well as the differences in technical conditions, the structural types of high-speed bogies developed by various countries are also quite different. However, the consensus on design principles and practical experience has led to many similarities in the form of high-speed bogies, such as the use of an air spring suspension system, wear-free axle box elastic positioning, and a composite brake system based on disc brakes…

Design principles of EMU bogies

(1) Use a highly flexible spring suspension system to obtain good vibration performance. This highly flexible air spring can show its superiority at speeds below 300km/h.

(2) Use a high-strength, lightweight bogie structure to reduce the dynamic effect between the wheel and the rail.

(3) Various measures that can effectively suppress bogie snaking and increase the critical speed of bogie snaking are adopted.

(4) The drive device adopts a simple, practical, reliable and mature structure and minimizes the unsprung mass and the sprung mass to improve the action force between the wheel and the rail and improve the stability of high-speed operation.

(5) The basic braking device adopts a composite braking system.

The tasks of the EMU bogie bogie

(1) Load-bearing. Bear the weight of all parts above the frame (including the car body, frame, power unit auxiliary devices, etc.) and distribute the axle weight evenly.

(2) Traction (power bogie). Ensure the necessary wheel-rail adhesion and transfer the wheel traction generated at the wheel-rail contact to the frame and coupler to pull the train forward.

(3) Buffering. Alleviate the impact of track unevenness on the vehicle and ensure that the vehicle has good running smoothness and stability.

(4) Guidance. Ensure that the vehicle passes the curve smoothly.

(5) Braking. Generate the necessary braking force to slow down or stop the vehicle within the specified distance. EMU bogies The main technical features of EMU bogies are bolster-less bogies, high-speed stability and curve passing performance; lightweight structure; all wheels are equipped with mechanical brake discs; EMU bogies are equipped with small induction motors; trailer bogies are equipped with mechanical or eddy current brake discs on the axles; all wheels are equipped with tread cleaning devices, and electronic anti-skid devices have achieved reduced driving noise and improved wheel-rail adhesion. Axle disc brake device Tread cleaner Wheel disc brake device EMU bogies

Basic requirements for high-speed bogies

Good running stability and comfort (dynamics)

Simple structure and lightweight (reliability)

Convenient and excellent maintenance

Safety against derailment (dynamics)

Classification by axle box positioning method

At present, the differences in the structural types of most EMU bogies are mainly reflected in the differences in axle box positioning methods. The mechanism that constrains the relative movement between the wheelset and the frame is called the axle box positioning device. The basic requirements for the axle box positioning device are: it should have appropriate elastic positioning stiffness values ​​in the longitudinal and transverse directions, and its value is the main parameter of the device; its structural form should be able to ensure good elastic positioning, stable performance, simple and reliable structure, no or little wear, easy manufacturing and maintenance, lightweight, low cost, etc. EMU bogie

Tie rod type (axle beam type) positioning

The two ends of the tie rod are pinned to the frame and the axle box, respectively. The tie rod can allow the axle box and the frame to have a large relative displacement in the vertical direction. The rubber pads and sleeves in the tie rod limit the lateral and longitudinal relative displacement between the axle box and the frame, respectively, realizing the elastic positioning of the EMU bogie 2. Pull plate type (support plate) positioning A thin positioning pull plate made of special spring steel is connected to the axle box at one end and connected to the frame through a rubber node at the other end. The different stiffness of the pull plate in the longitudinal and transverse directions is used to constrain the relative movement of the frame and the axle box to achieve elastic positioning.

EMU bogie

Characteristics of high-speed EMU bogie: Good and excellent maintainability Bogie structure that is easy to assemble and disassemble Two-part axle box structure that is convenient for wheelset replacement No sliding parts, can be maintenance-free for a long time EMU bogie Simple structure and lightweight swing arm axle box support positioning device No rocker frame and car body support device Single-link traction device Lightweight and strength and reliability combined bogie frame EMU bogie

Any railway locomotive vehicle bogie must complete the following tasks:

(1) Load-bearing. Bear the weight of all parts above the frame (including the car body, frame, power unit auxiliary devices, etc.), and evenly distribute the axle weight.

(2) Traction (power bogie). Ensure the necessary wheel-rail adhesion and transfer the wheel circumference traction generated at the wheel-rail contact point to the frame and coupler to pull the train forward.

(3) Buffering. Alleviate the impact of uneven lines on the vehicle and ensure that the vehicle has good running stability and stability.

(4) Guidance. Ensure that the vehicle passes through the curve smoothly.

(5) Braking. Generate the necessary braking force to slow down or stop the vehicle within the specified distance.

Of course, the non-powered bogie does not generate a driving force. It is pulled by others so that it can have no traction (task).

Technical performance requirements of EMU bogies

(1) The mutual dynamic effect between the wheel and the rail is significantly enhanced, which directly affects the smoothness and safety of the vehicle operation and also has an adverse effect on the strength and stability of the track line.

(2) For lateral motion stability, higher requirements are put forward. Attention must be paid to the occurrence and intensification of bogie instability to prevent violent snaking movement.

(3) When passing through a curve at high speed, the lateral dynamic effect increases. It is necessary to prevent derailment and overturning and prevent the expansion of the track gauge and lateral movement of the track row.

(4) The increase in movement speed increases the frequency of vibration caused by track unevenness, which intensifies the frequency of vehicle disturbance. It will affect the smoothness of vehicle movement.

(5) Attention must be paid to the environmental pollution caused by noise generated during high-speed operation