Home | Bridge Pictures | Bascule Bridges
- Bascule bridges have counterbalance weights positioned either in the deck or in overhead
balance frames (as shown) to assist in the lifting operation of the deck.
The bridge shown consists of a moveable deck (C-D), tie rods (A-D), a balance frame including counterweights (A-B-E), and a portal support frame. In order to guarantee equilibrium at every position during lifting, it is necessary to locate the pin connections in the balance frame at the vertices of a parallelogram (A-B-C-D).
As a second condition the virtual line between pivot B and the centre of gravity of the whole balance frame E, should be parallel to the virtual line between pivot C and the centre of gravity of the deck (approximately point D in the bridge shown)
