Carter Bros 5' wheel base Fn3 1:20.3 scale passeng

This model does not have any spring action. It is designed to attach to the bolster by clicking together. The attachment point allows for a certain amount of rotation of the side frame to allow the wheels to stay in contact with the rails on rough track. The end beams are designed to be pinned to the end of the frame and therefore not a solid joint which allows the truck to twist as it encounters rough track.