Spillway gates and radial gate

Types of spillway gates

1. Vertical lift gates – plain sliding, fixed-wheel (roller) and Stoney gates
2. Radial (Tainter) gates
3. Drum gates
4. Sector gates
5. Rolling (roller) gates
6. Flap gates
7. Flash boards and stop logs

Radial (Tainter) gate

A radial gate has a curved steel skin plate, which is a part of a cylinder, supported by radial arms that converge to trunnion pins fixed on the piers. The gate rotates about the trunnion to open or close.

              hoist rope
               |
     ~~~~~~~~~ |\   skin plate (curved)
   reservoir   | \
   ~~~~~~~~~~~ |  \ ---- arm ----o trunnion
               |  /               (on pier)
               | /  ---- arm ---/
   ____________|/__________________
         crest   sill    flow -->

Working and features:

• The skin plate is curved concentric with the trunnion, so the resultant water pressure passes through the trunnion pin. Water pressure therefore produces no moment about the pin, and the hoist only lifts the gate's own weight and overcomes pin and seal friction.
• The gate is raised by rope or chain hoists or hydraulic cylinders; water flows under the gate.
• Rubber seals at the sides and bottom make it watertight; no deep slots in piers are needed, so flow is smooth.

Advantages: small hoisting force, simple and reliable, good for large openings (up to about 20 m × 20 m), easy automatic control, cheaper than vertical gates of the same size.

Disadvantages: piers must be long to hold the trunnions; trunnion anchorage carries large concentrated loads; requires accurate fabrication.