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