Railway vehicle axle box: structure, function and positioning mode are fully analyzed

1.Overview of axle boxes

On railway locomotives and vehicles, the parts that are mounted on the axle neck and connect the wheel set and the bogie frame or the two-axle vehicle body are referred to as axle boxes.

2.Functions and forms of axle boxes

Functions

• Active joints – active joints that connect the wheelset and the frame
• Force transmission – transmission of traction, lateral force and vertical force
• Movement – vertical and lateral movement between the wheelset and the frame.

Forms

• According to the bearing type, there are: sliding bearing axle boxes and rolling bearing axle boxes. Modern locomotives all use rolling bearing axle boxes.
• According to the positioning method, there are: guide frame type positioning and guide frameless type positioning.

Among them, the non-guide frame type positioning can be divided into the pull plate type positioning and the pull rod type positioning used for Dongfeng 4 series and Dongfeng 8 series diesel locomotives, the swing arm type positioning used for Beijing subway vehicles DK3 and Tianjin light rail vehicles, the herringbone rubber positioning used for Shanghai subway vehicles SMC, the stacked cone rubber positioning used for Beijing urban rail vehicles, and the guide column type positioning – etc. 5 axle box positioning methods.

3.Detailed introduction to several types of non-guide frame type positioning

• Pull plate type positioning: A thin sheet-shaped 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. Features: The pull plate has a small bending stiffness up and down, and the relative displacement constraint on the axle box and the frame in the vertical direction is very small.
• Pull rod type positioning: The two ends of the pull rod are pinned to the frame and the axle box respectively. The rubber pads and sleeves at both ends of the pull rod limit the lateral and longitudinal relative displacement between the axle box and the frame respectively to achieve elastic positioning. The pull rod allows the axle box and the frame to have a large relative displacement in the vertical direction.
• Swivel arm positioning: Also known as elastic hinge positioning, one end of the positioning swing arm is fixed to the cylindrical axle box body, and the other end is connected to the mounting seat on the frame with a rubber elastic node. Features of elastic nodes: Allow the frame to have a large displacement in the vertical direction, and the rubber parts in the elastic node are designed to make the axle box have appropriate different positioning stiffness requirements in the longitudinal and transverse directions.
• Stacked rubber spring positioning: A compression-reduced stacked rubber spring is installed between the frame and the axle box. Its vertical stiffness is small, so that the axle box has a large vertical displacement relative to the frame, and it has appropriate stiffness in the longitudinal and transverse directions to achieve good elastic positioning.
• Dry friction guide column positioning: The guide column installed on the frame and the support ring located on the axle box spring tray are both equipped with wear sleeves. The guide column is inserted into the support ring. When the frame and the axle box move up and down, the two wear sleeves produce dry friction. Its positioning function is to transmit longitudinal force and lateral force through the guide column and the support ring, and to produce shear deformation in different directions through the rubber pad to achieve elastic positioning.