LOCK GATES AND VALVES. i'gx 



arms of the gate at the approach of the high-water season, and removed when it has 

 passed. 



Operation of Gates. For opening or closing gates the most common method in 

 use, and probably the best one for ordinary conditions, consists in a spar, provided 

 with a cast-iron rack, and worked by a gear-wheel on a capstan, or a spar without any 

 rack and worked by two capstans and lines, one for pulling the gate open, the other for 

 pulling on the outer end of the spar and closing it. The spars as a rule should be 

 attached close to the ends of the gates, so as to utilize all the leverage available, although 

 in many cases the attachment is made at a distance from the toe equal to one-third 

 of the length of the gate, for the sake of using a shorter spar. Where the latter is long, 

 and overhangs the wall, as on the river side, a light movable bracket carrying a roller is 

 used to support the free end, attached to the wall in a way to permit its removal for 

 an approaching flood. 



In large gates chains are frequently used, attached to the bottom of the leaf, the 

 closing chain crossing the chamber and passing up the opposite wall. Steam or water 

 supplies the operating power. In several large locks of recent construction in Europe, 

 as on the North Sea and Baltic Canal, the method of chains has been discarded, and a 

 steel strut substituted, placed above water, where it can be easily reached for repairs, 

 an advantage which chains do not possess. It is worked in some cases by an hydraulic 

 cylinder, and in others by geared turbines, and would appear preferable in many ways 

 to the use of chains. 



The old method of a balance-beam has also been applied occasionally, the top 

 beam of the gate being extended back to form an arm to which a rope is attached, 

 wound by a capstan, or a link chain worked by sprocket wheels and levers. 



Electric motors have been applied in recent years to the operation of gates, 

 apparently with good success, and examples of them may be seen on the Canadian lock 

 at Sault Ste. Marie, and on the Amsterdam Ship Canal. 



Where practicable it is a good plan to place the spars below the coping, so 

 they will not be in the way of the lock-tenders during maneuvers. This method is 

 in use on the Moldau in Bohemia, and on the Fox River in Wisconsin, and has proved 

 very satisfactory. The spars work in recesses covered by cast-iron plates. 



No simple and practical formula has yet been given to determine the power needed 

 to move a lock gate. With small gates the displacement of the water takes a large 

 proportion of the power required, but with gates of moderate or large size the friction, 

 and sometimes the effect of wind, are the chief factors to be overcome. We give below 

 the sizes of spur-wheels, etc., used in certain examples, all the gates being operated by 

 spars and pinion-wheels, turned by levers. The opening or closing under ordinary 

 conditions could be easily accomplished by one man. The spars were attached near 

 the ends of the gates, and the levers were 4 to 5 feet long. 



Gate 12 in. thick, 15 ft. 9 in. long, 22 ft. o in. high, pitch diameter of spur-wheel u J in. 

 " 15 " " 21 " 9 " " 29 " 6 " ....... ' " " 8J| " 







