Lock nut

Posted on 24 июня, 2018 by minini

Enter the characters you see below Sorry, we just need to make sure you’re not lock nut robot. Example Domain This domain is for use in illustrative examples in documents. You may use this domain in literature without prior coordination or asking for permission. Not to be confused with Loch. A lock is a device used for raising and lowering boats, ships and other watercraft between stretches of water of different levels on river and canal waterways. Locks are used to make a river more easily navigable, or to allow a canal to cross land that is not level. Later canals used more and larger locks to allow a more direct route to be taken.

Since 2016, the largest lock worldwide is the Kieldrecht Lock in the Port of Antwerp, Belgium. A pound lock is a type of lock that is used almost exclusively nowadays on canals and rivers. A pound lock has a chamber with gates at both ends that control the level of water in the pound. In contrast, an earlier design with a single gate was known as a flash lock. Song politician and naval engineer Qiao Weiyue in 984.

The distance between the two locks was rather more than 50 paces, and the whole space was covered with a great roof like a shed. In medieval Europe a sort of pound lock was built in 1373 at Vreeswijk, Netherlands. In large scale river navigation improvements, weirs and locks are used together. A weir will increase the depth of a shallow stretch, and the required lock will either be built in a gap in the weir, or at the downstream end of an artificial cut which bypasses the weir and perhaps a shallow stretch of river below it. Sometimes a river is made entirely non-tidal by constructing a sea lock directly into the estuary. In more advanced river navigations, more locks are required. Where a longer cut bypasses a circuitous stretch of river, the upstream end of the cut will often be protected by a flood lock.

The longer the cut, the greater the difference in river level between start and end of the cut, so that a very long cut will need additional locks along its length. At this point, the cut is, in effect, a canal. Locks of the Panama Canal during construction, 1913. As engineers became more ambitious in the types of country they felt they could overcome, locks became essential to effect the necessary changes in water level without detours that would be completely uneconomic both in building costs and journey time. A plan and side view of a generic, empty canal lock. A lock chamber separated from the rest of the canal by an upper pair and a lower pair of mitre gates. The lock is filled with water from upstream.

The lock is emptied by draining its water downstream. A watertight chamber connecting the upper and lower canals, and large enough to enclose one or more boats. The position of the chamber is fixed, but its water level can vary. A set of lock gear to empty or fill the chamber as required. The principle of operating a lock is simple. The entrance gates are opened and the boat moves in.

A valve is opened, this lowers the boat by draining water from the chamber. The exit gates are opened and the boat moves out. If the lock were empty, the boat would have had to wait 5 to 10 minutes while the lock was filled. The whole operation will usually take between 10 and 20 minutes, depending on the size of the lock and whether the water in the lock was originally set at the boat’s level. However, this is not true for staircase locks, where it is quicker for boats to go through in convoy. For simplicity, this section describes a basic type of lock, with a pair of gates at each end of the chamber and simple rack and pinion paddles raised manually by means of a detachable windlass operated by lock-keepers or the boat’s shore crew. This type can be found all over the world, but the terminology here is that used on the British canals. A subsequent section explains common variations.

The rise is the change in water-level in the lock. On American canals, a pound is called a level. The chamber is the main feature of a lock. The cill, also spelled sill, is a narrow horizontal ledge protruding a short way into the chamber from below the upper gates. Allowing the rear of the boat to «hang» on the cill is the main danger when descending a lock, and the position of the forward edge of the cill is usually marked on the lock side by a white line. The edge of the cill is usually curved, protruding less in the center than at the edges. Gates are the watertight doors which seal off the chamber from the upper and lower pounds.

A balance beam is the long arm projecting from the landward side of the gate over the towpath. Typically, a square-section stub emerges from the housing of the winding gear. During the 1980s, British Waterways began to introduce a hydraulic system for operating paddles, especially those on bottom gates, which are the heaviest to operate. A metal cylinder about a foot in diameter was mounted on the balance beam and contained a small oil-operated hydraulic pump. A spindle protruded from the front face and was operated by a windlass in the usual way, the energy being transferred to the actual paddle by small bore pipes. Note: rakes are for clearing trash out of the lock.

The simplest windlass is made from an iron rod of circular section, about half an inch in diameter and two feet long, bent to make an L-shape with legs of slightly different length. The shorter leg is called the handle, and the longer leg is called the arm. Welded to the end of the arm is a square, sometimes tapered, socket of the correct size to fit onto the spindle protruding from lock winding gear. Socket: Traditionally, windlasses had a single socket, designed for a particular canal. When undertaking a journey through several canals with different lock-gear spindle sizes it was necessary to carry several different windlasses. Handle: The handle is long enough for a two-handed grip and is far enough from the socket to give enough leverage to wind the paddle up or down. There may be a freely rotating sleeve around the handle to protect the hands from the friction of rough iron against skin.

Arm: A «long throw» windlass has a longer arm so that the handle is further from the socket to give a greater leverage on stiffer paddles. If the throw is too long then the user, winding a gate paddle, risks barking their knuckles against the balance beam when the handle is at the lowest point of its arc. A sophisticated modern windlass may have an adjustable-length arm. Materials: Early windlasses were individually hand forged from a single piece of wrought iron by a blacksmith. On the Chesapeake and Ohio Canal, the lockkeepers were required to remove the windlasses from all lock paddles at night, to prevent unauthorized use. A swell was caused by opening suddenly the paddle valves in the lock gates, or when emptying a lock. On the Erie Canal, some loaded boats needed a swell to get out of the lock, particularly lumber boats, being top heavy, would list to one side and get stuck in the lock, and needed a swell to get them out. Some lockkeepers would give a swell to anyone to help them on the way, but some would ask for money for the swell.

The Erie Canal management did not like swelling for two reasons. First, it used too much water lowering the water on the pound above sometimes causing boats to run aground. In addition, it raised the water level on the pound below causing some boats to strike bridges or get stuck. Lock mooring» was a commonly used method of navigating into a lock by a barge travelling upstream. The barge would be directed to the slack water to one side of the lock gates and as the volume of water decreased as the lock emptied the barge or boat is effectively sucked out of the slack water into the path of the lock gates. The effort required to navigate the barge or boat into the mouth of the lock was therefore substantially reduced. Snubbing a boat to keep it from hitting the downstream gates. Note the rope wrapped around the snubbing post.

On horse-drawn and mule-drawn canals, snubbing posts were used to slow or stop a boat in the lock. A 200-ton boat moving at a few miles an hour could destroy the lock gate. To prevent this, a rope was wound around the snubbing post as the boat entered the lock. Pulling on the rope slowed the boat, due to the friction of the rope against the post. One incident, which took place in June 1873 on the Chesapeake and Ohio Canal, involved the boat the Henry C. Lock 74, moving in front of another boat. Because they failed to snub the boat, it crashed into and knocked out the downstream gates. A series of photos of the Canadian Locks in Sault Ste.

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Variations exist for types of locks and the terminology used for them. On most English narrow canals, the upper end of the chamber is closed by a single gate the full width of the lock. This was cheaper to construct and is quicker to operate with a small crew, as only one gate needs to be opened. These were often fitted with a post allowing a rope to be used to stop the boat and close the gate at the same time. They have single gates at the lower end also. Even very large steel-gated locks still can use essentially the same swinging gate design as small 250-year-old locks on the English canals.

On English canals, steel gates usually have wooden mitre posts as this gives a better seal. The sliding gates of the Nieuwe Meersluis in Amsterdam double as roadways. A kind of sliding gate that is hollow and can float. It can be constructed to withstand high heads. Some of these were installed on the Chesapeake and Ohio Canal in the congested 7 Locks area since they could be operated by one man and also could speed up traffic. Some of these work very like traditional swinging gates, but with each gate in the form of a sector of a cylinder. They close by rotating out from the lock wall and meeting in the centre of the chamber.

Water is let in or out by opening the gates slightly: there may be no paddles or other lock gear. On the Leeds and Liverpool Canal there is a variety of different lock gear. Others are operated by lifting a long wooden lever, which operates a wooden plate which seals the culvert. These are known locally as «jack cloughs». On some parts of the Montgomery Canal bottom paddles are used in place of side paddles. Rather than passing into the lock through a culvert around the side of the lock gate, the water flows through a culvert in the bottom of the canal. The paddle slides horizontally over the culvert. To economise, especially where good stone would be prohibitively expensive or difficult to obtain, composite locks were made, i.





This is particularly true on commercial waterways, or where locks are large or have complicated features that the average leisure boater may not be able to operate successfully. On large modern canals, especially very large ones such as ship canals, the gates and paddles are too large to be hand operated, and are operated by hydraulic or electrical equipment. Some fish such as lampreys, trout and salmon go upstream to spawn. Measures such as a fish ladder are often taken to counteract this. Navigation locks have also potential to be operated as fishways to provide increased access for a range of biota. A weigh lock is a specialized canal lock designed to determine the weight of barges to assess toll payments based upon the weight and value of the cargo carried. The Erie Canal had weigh locks in Rochester, Syracuse, and West Troy New York.



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In medieval Europe a sort of pound lock was built in 1373 at Vreeswijk, about half an inch in diameter and two feet long, empty canal lock. For instance in the case of the Hollandic Water Line. 225 m length — the chamber is the main feature of a lock. Allowing the rear of the boat to «hang» on the cill is the main danger when descending a lock; in more advanced river navigations, navigation locks have also potential to be operated as fishways to provide increased access for a range of biota. A flight of locks is simply a series of locks in close, enough proximity to be identified as a single group.

Loosely, a flight of locks is simply a series of locks in close-enough proximity to be identified as a single group. Foxton flight consists entirely of two adjacent 5-chamber staircases. Where a very steep gradient has to be climbed, a lock staircase is used. There are two types of staircase, «real» and «apparent». A «real» staircase can be thought of as a «compressed» flight, where the intermediate pounds have disappeared, and the upper gate of one lock is also the lower gate of the one above it. However, it is incorrect to use the terms staircase and flight interchangeably: because of the absence of intermediate pounds, operating a staircase is very different from operating a flight. In an «apparent» staircase the chambers still have common gates, but the water does not pass directly from one chamber to the next, going instead via side ponds. This means it is not necessary to ensure that the flight is full or empty before starting.

Examples of famous «real» staircases in England are Bingley and Grindley Brook. Operation of a staircase is more involved than a flight. Inexperienced boaters may find operating staircase locks difficult. In a staircase, however, it is quicker for a boat to follow a previous one going in the same direction. As with a flight, it is possible on a broad canal for more than one boat to be in a staircase at the same time, but managing this without waste of water requires expertise. This is on the Erie Canal at Lockport. Locks can be built side by side on the same waterway. This is variously called doubling, pairing, or twinning. The Panama Canal has three sets of double locks.

Doubling gives advantages in speed, avoiding hold-ups at busy times and increasing the chance of a boat finding a lock set in its favour. The once-famous staircase at Lockport, New York was also a doubled set of locks. Niagara Escarpment, a considerable engineering feat in the nineteenth century. During the competitive years of the English waterways system, an established canal company would often refuse to allow a connection from a newer, adjacent one. Normally, they would specify that, at the junction, the newer canal must be at a higher level than their existing canal. Many stop locks were removed or converted to a single gate after nationalisation in 1948. M would always be lower than the Macclesfield. The newer canal was not always at a higher level than the one it joined.

There are several examples where locks have been built to a round plan, with more than two exits from the lock chamber, each serving a different water level. Thus the lock serves both as a way of changing levels and as a junction. The circular plan of the lock allows boats within it to rotate to line up with the appropriate exit gate. The best known example of such a round lock is the Agde Round Lock on the Canal du Midi in France. This serves as a lock on the main line of the canal and allows access to the Hérault River. A second French round lock can be found in the form of the, now disused, Écluse des Lorraines, connecting the Canal latéral à la Loire with the River Allier. A drop lock allows a short length of canal to be lowered temporarily while a boat passes under an obstruction such as a low bridge.

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