User:Mvs murthy/sandbox

2. SPILLWAY GATES  - MAINTENANCE   AND   OPERATION Proper operation and maintenance of spillway crest gates is very essential for conservation of water and also safety of the dam and other structures. In many cases, a substantial part of the storage is above the crest and behind the spillway gates. Generally, every dam head-works has a schedule of operating of gates indicating the sequence of opening of gates, the height of opening at a time,position of gate opening which should be avoided being harmful and checks to be carried out before comencing gate operation etc. This Schedule should be displayed prominantly at the Control room on the dam and should be meticulously followed.. Spillway crest gates could be of several types but most common types found in our country are: Radial gates such as those on Hemavathy - Harangi  in Karnataka and Ukai, Kadana and Khodyiar dams in Gujarat, Vertical lift gates such - as on Tungabhadra dam in Karnataka. We may consider radial gates first as these are more common. 2.1 .1  RADIAL GATES. A Radial gate is a gate in the shape of a segment of a cylinder rotating about its horizontal axis. The general layout of a radial gate is at Plate(1) Radial Gates are most suitable for spillways because of several advantages they have over other types: 1) Simplicity of construction  	2) Light Weight 3) Low hoist capacity  	4) Reduction in height of pier 5) Smooth flow 	6) Larger span 7) Less maintenance  	8)  Less vibration during partial opening However, there are a few disadvantages: (1) To accommodate the location of trunnions, the piers would have to be extended in the downstream which may increase the cost.