Draaistelframe

Draaistelframe is the structural frame of a bogie (draaistel) in rail vehicles. It forms the rigid core that carries wheelsets and provides mounting points for suspension and for attachment to the vehicle body. The frame is typically built from steel and consists of side frames connected by cross-members, sometimes with a central bolster or pivot housing. The wheelsets and axles are mounted in bearing housings within the frame, and the bogie provides a pivot that allows the bogie to rotate relative to the car body when negotiating curves.

Draaistelframe supports primary and secondary suspension: between wheelset and frame there are springs or elastomeric elements (primary suspension), and between frame and vehicle body there is secondary suspension such as springs and dampers. Some designs integrate the bolster into the frame, others use separate casting. Modern bogies may use welded or cast components and hollow-section frames for strength and stiffness, and may include anti-roll devices to improve stability. The frame distributes vertical and lateral forces to the wheel-rail interface and is subject to regular inspection for cracks, corrosion, and wear. Replacement of a bogie frame is a major maintenance operation, typically performed as part of a bogie overhaul.