rents set up during the filling or emptying pro-
slower motion. Gate motion could be pro-
cess. For these reasons, filling and emptying
grammed so that the acceleration and decelera-
valves that are operated according to pre-estab-
tion would take place identically every lockage
lished programs can be made to function accord-
cycle without operator input (other than initiat-
ing to two or more programs of different dura-
ing the motion). Gate motion would thus be-
tions, adapted to various vessel types and their
come dependent on gate position within its
responses to the rate of change in lock chamber
range, according to a program.
water levels.
Latching gates in their recesses. Some locks have
Establishing and remotely resetting limit positions
latches for the lock gates that must be secured
of valves. Limit switches are vital safety features
when the gates are in the opened position and
on filling and emptying valve mechanisms for
before lock traffic is permitted. Some of these
protecting components from damaging over-
projects also latch the gates when passing ice
loads. It is likely that these electromechanical de-
over submergible bulkheads, to ensure that the
vices would be employed as separate backups
gates are not damaged by the flow through the
even with fully automated operation of filling
chamber. Latching is a manual procedure, or an
and emptying valves. The setting or adjustment
automatic mechanical procedure; unlatching is
of limit switches is often troublesome due to diffi-
manual in all cases. Latching and unlatching can
cult accessibility and the need for fine tuning. Re-
be automated by programming latching to occur
mote setting of limit switches could be accom-
at a certain gate position and unlatching to occur
plished by relatively simple automated means.
at the beginning of gate closure motion. Auto-
This would facilitate setting of limit switches, but
mated latching/unlatching could also be chosen
especially would allow ease in changing the set-
as an interlock condition for other programmed
tings to meet temporary needs imposed by such
operations.
conditions as worn or damaged machinery com-
Interlocking gate operation between upper and
ponents or foreign material (debris or silt) inter-
lower gates. In ordinary operations, the upper
fering with valve operation.
and lower gates are never open at the same time.
Interlocking valve operation with upper and/or low-
The closed gate must be fully closed before the
er gate operation. At almost all lock projects it is
other gate is opened. Usually this is verified vi-
the operator's responsibility to ensure that the
sually by the operators, and may be done with
lock gates are fully closed before filling or empty-
or without reference to indicators in the lock
ing operations are begun. Serious accidents and
stands. A mistake by an operator could be quite
equipment damage are possible if filling or
damaging to the gates and the lock. Automation
emptying operations are attempted prematurely.
equipment on the gate operating mechanisms
By having automated equipment monitoring the
will input gate position information to a pro-
operations of the lock gates, operational pro-
gram, and it would be an easy matter to create
grams can be designed to prevent filling or
an interlock in the program that requires one
emptying operations from being attempted until
gate to be fully closed before the other can be
a specified condition or position is achieved at the
opened.
lock gates.
Interlocking gate operation with filling and
emptying valve operation. One of the potentially
Gate opening and closing
most hazardous and damaging operator errors
While there is a variety of lock gate designs in
that can occur at a lock is to begin opening an
use at Corps projects (e.g., miter gates, sector
upper gate before the chamber is substantially
gates, lift gates, guillotine gates, tainter gates), the
filled, or to begin opening a lower gate before a
operation of them is critical to the efficiency of
chamber is substantially emptied. The gates are
lock operation. Some operational concerns apply
vulnerable to damage, and if they were to be-
to all types of gates, while others apply only to
come inoperative, there could be an uncon-
certain gate types.
trolled flow situation through the lock. This is
Controlling rate of gate motion. Operators control
essentially the same problem that was stated
the speed of motion of most types of lock gates.
earlier under filling and emptying operations,
Motion is begun and ended slowly, and in the
but in this case from the point of view of operat-
middle ranges of motion the lock gates are gener-
ing the lock gates. Thus, by having automated
ally permitted to move at maximum speed, bar-
equipment monitoring the operations of the fill-
ring any unusual conditions that would require
ing and emptying valves, operational programs
6
Previous Page
