Volume 8 – Mechanical and Electrical Services - Malaysia Geoportal

Chapter 2 GATE DESIGN
The disadvantages of vertical lift gates include a heavier lifting load, which requires greater hoist
capacity; pier-height requirement; greater time required for gate operation and gate slots that can
lead to cavitation and debris collection.
b) Multistage wheel gate
A multistage or multi-section gate consists of two or more sections in the same slot with variable
discharge between the sections or between the bottom section and the sill. Multi-section gates can
be equipped with a latching mechanism to allow its use as a single section gate.
2.2.2 Hinged Type
a) Radial gate
The radial gate is a segment of a cylinder mounted on radial arms that rotate on trunnions anchored
to the piers. Normally the water is against the convex side of the gate. The radial gate has an
upstream skin plate bent to an arc, with convex surface of the arc on the upstream side (See Fig.
2.10). Pressure is transferred from the curved face through the horizontal face support beams to the
radial arms at the sides of the openings. The arms act as columns and transfer thrust to a common
bearing located on either side of the gate opening. This design results in a light-weight, economical
gate that can be operated with minimum effort and a comparatively small number of turns of the
hand-wheel on the hoist.
Figure 2.10 Radial Gate
Radial gates could be of two types of installation depending on application. The most common type
is the overflow type, where the gate is designed for 1 foot of water flowing over the top of the gate.
Adequate safety factors in the design prevent damage to the gate if a moderate additional overflow
is increased beyond that limit for a short period of time (See Fig. 2.11).
The second type is the breast wall type where a vertical wall is constructed over the top of the gate
opening resulting in additional storage capacity in front of the gate. The gate has to be designed for
this higher head (See Fig. 2.12).
March 2009 2-9