Radial gate
Radial gates consists of a skin plate formed into a segment with radius about the pivot. The skin plate is stiffened by vertical or horizontal members. The assembly is supported by two or more radial arms at each side which converge downstream at the trunnions. At the trunnions they are anchored to piers and transfer the entire thrust of water load to the civil engineering structure. The resultant of the water load passes through the trunnion pins.
The design of the radial gate means that there is little hoisting forces required for maneuvering the gate. This is due to the shape that makes the resultant of the water load pass through the trunnion pins. There are therefore no unbalanced moment to overcome and the hoisting load therefore consists of the weight of the gate, the friction from the side seals as well as friction in the trunnions. The advantages and disadvantages of a radial gate is listed below.
Advantages
- Absence of gate slots
- Gate thrust transmitted to two bearings only
- Less hoisting capacity required than for vertical lift gate
- Geometry provides favourable hydraulic discharge
- Location of bearings is above level of discharge
- The civil structure required is quite low. If there is a road going over the dam, no large additional structure is required
- The gate is stiff structurally
- There is no possibility for trash jamming the wheels
Disadvantages
- Flume walls must extend downstream at sufficient height to provide attachment for gate trunnions
- The gate water loads is taken by the piers as concentrated loads at gate anchorages
- Increased fabrication complecity compares to vertical lift gates
- Will not pass floating material until 75% open (find source)
