4.3 Spillway gates

Dropping Shutter or Flash boards

Drum Gates

Vertical Lift Gates or Rectangular Gates

These are rectangular gates spanning horizontally between groves made in supporting spillway piers. These groove guides are lined with rolled steel lined sections. Rectangular gates made of steel move between grove guides can be raised or lowered by hoisting mechanism at top. To overcome friction between gate and dls groove guides, cylindrical rollers are placed between bearing surface of gate and the guide grooves.

Large vertical lift gates may be counter balanced by a counter weight beam which is loaded to balance the self weight of gate. Generally size of gates provided are 15cmx15cm.

Radial Gates or Taiter Gates

A radial gate has curved water supporting face made of steel. The curved water face which is in shape of sector of a circle is properly braced by steel framework pivoted on horizontal shafts called trunnions or pins. The pins are anchored in d/s portion of the spillway piers. The gate thus rotates about fixed horizontal axis. Hoisting cables are attached to the gate and lead to winches on hoisting platform. The winches are usually motor driver.

As water face segment is concentric to supporting pins, water passes through pins exerting no moment against lifting of the gate. Counter weights in order to counter balance the self weight may also be used which further reduces lifting force.

Vishwashwaraiya Gates