Fabrication of Vertical Bridge Lifting Mechanism
A vertical-lift bridge or lift bridge is a type of movable bridge in which as pan rises vertically while remaining parallel with the deck which ensures passing of ships underneath. They cost less to build for longer moveable spans. The counterweights in a vertical lift are only required to be equal to the weight of the deck.
Thus heavier materials can be used in the deck, and so this type of bridge is especially suited for heavy railroad use. It is also more energy efficient, requiring comparatively less power to lift the bridge. The project is a prototype of such a bridge and utilizes a chain drive mechanism to lift the middle span of the bridge.
Lift bridges state of the art:
Among mobile bridges, lift ones appear as the right answer when relatively long spans are needed. Bascule bridges or rotating ones are more limited, because of their overhanging decks. In France the existing lift bridge with the longest span is “Recouvrance” Bridge in Brest, with an 87.5 meters lifting span.But most large bridges of this kind are located in New Jersey, USA where manywaterways allow maritime traffic.
The longest lifting span in the world belongs to Arthur Kill Bridge with 170 meters, no longer in operation. Another significant structure is the Gil Hodges Memorial Bridge, with a main span in the range of 160 meters.
When a handle attached at the bottom is rotated the middle span is lifted by 2ropes, 1 at each extremity. The ropes are attached to the 2 S-hooks which raise the bridge span.
The ropes which go over the side pulleys wrap around the central pulley thus shortening the length of ropes and causing lifting.
- It is simple mechanism.
- Cost wise low construction.
- If handled is easy.
- If maintenance cost is very high.
- If it is difficult alignment.
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