The key is a tool used to raise and lower ships, boats and other ships between stretching water from different levels in the river and channel waterways. The distinguishing feature of the key is the fixed space where the water level may vary; while in a caisson key, a boat lift, or on a slanted plane of a canal, it is the space itself (usually called caisson) that goes up and down.
Locks are used to make the river easier to navigate, or allow the canal to cross uneven ground. The next channel uses more and larger keys to allow a more direct route to retrieve.
Since 2016, the largest lock in the world is Kieldrecht Key in the Port of Antwerp, Belgium.
Video Lock (water navigation)
Pound lock
The key pound is the key type used almost exclusively today in channels and streams. The pound key has a space with a gate at both ends that controls the water level in pounds. In contrast, the previous design with a single gate is known as a flash key.
The Pound Key was first used in medieval China during the Song Dynasty (960-1279 AD), which had been pioneered by Song politicians and naval engineer Qiao Weiyue in 984. They replaced the previous double slide which has caused problems and is mentioned by the Chinese polymath. Shen Kuo (1031-1095) in his book Dream Pool Essays (published in 1088), and is fully described in Chinese historical text Song Shi (compiled in 1345):
The distance between the two keys was somewhat more than 50 steps, and the entire room was covered with a large roof like a shed. The gate was 'gate hanging'; when they are closed, water accumulates like a tide until the required level is reached, and then when the time comes it is allowed to flow out.
The height of the water can be different from 4 feet (1.2 m) or 5 feet (1.5 m) in each key and on the Grand Canal the level is raised in this manner by 138 feet (42 m).
In medieval Europe a kind of key pound was built in 1373 in Vreeswijk, The Netherlands. This pound lock serves many ships at once in a large basin. But the first true pound key was built in 1396 at Damme near Bruges, Belgium. Italy Bertola da Novate (ca. 1410-1475) built the 18-pound lock on Naviglio di Bereguardo (part of Milan's canal system sponsored by Francesco Sforza) between 1452 and 1458.
Maps Lock (water navigation)
When a river bed is made navigable, keys are sometimes required to pass obstacles such as quick dams, dams, or factory weirs - due to changes in river levels across obstacles.
In the enhancement of large-scale river navigation, weirs and locks are used together. The bend will increase the depth of the shallower expanse, and the necessary locks will also be built in the gap in the weir, or at the cutting edge of the cutting edge that passes over the weir and may be shallow. stretch of river below. Rivers that are improved in these ways are often called Waterway or River Navigation (see the Calder and Hebble Navigation example).
Sometimes streams are made entirely non-ups and downs by building a sea lock directly to the estuary.
In the more advanced river navigation, more keys are required.
- If a longer piece passes over a circular river bed, the upstream end of the piece will often be protected by a flood key .
- The longer the snippet, the greater the level of the river between the beginning and the end of the piece, so that a very long piece will require an additional key along its length. At this point, the deduction is, in essence, a channel .
Use in channel
A truly artificial canal, in fairly flat rural areas, will surround a small hill or depression by simply rotating (contouring) around it. When engineers become more ambitious in the kinds of countries they feel they can overcome, keys become important to influence the necessary changes in water levels without detours that would be completely uneconomical both in building cost and travel time. After that, as construction techniques increase, engineers become more willing to cut directly through and through obstacles by building long tunnels, cuttings, waterways or embankments, or to build more technical devices such as sloping planes or boat lifts. However, the key continues to be built to complement this solution, and is an essential part of most modern waterways.
Basic construction and operations
All pound keys have three elements:
- An impermeable space connects up and down channels, and large enough to include one or more boats. The room position is fixed, but the water level can vary.
- A gate (often a pair "pointing" half-gate) at each end of the room. A gate is opened to allow the boat to enter or leave the room; when closed, the gate is watertight.
- One set of
keys to empty or fill the space as needed. This is usually a simple valve (traditionally, flat panel (paddle) lifted by manually rotating the rack and pinion mechanisms) that allow water to flow in or out of the room; Larger keys can use the pump.
The principle of operating the lock is simple. For example, if a ship traveling downstream finds a key that is already filled with water:
- The entrance opens and the boat moves in.
- The entrance is closed.
- Open valve, this lowers the boat by draining water from the room.
- The exit door opens and the boat moves out.
If the padlock is empty, the boat must wait 5 to 10 minutes while the key is filled. For a boat that travels upstream, the process is reversed; the boat enters the empty key, and then the space is filled with a valve opening that allows water to enter the room from the upper level. The entire operation will usually take between 10 and 20 minutes, depending on the size of the lock and whether the water in the lock is initially set at the boat level.
Boaters approaching the keys are usually happy to meet other boats coming in their direction, because these boats will have just come out of the lock on their level and therefore set up their lucrative locks - saves about 5 to 10 minutes. However, this is not true for key stairs, where it is faster for ships to be traversed within a convoy.
Details and terminology
For simplicity, this section describes the basic key types, with a pair of gates at each end of the room and a simple rack and paddle pinion that is lifted manually using a removable locker machine operated by a lock-keeper or crew. This type can be found all over the world, but the terminology here is used on English channels. The next section describes general variations.
Rise
The rises is the water level change in the key. The two deepest keys in the British canal system are keys in Bath on Kennet and Avon Canal and Tuel Lane Lock on the Rochdale Canal, both of which have a nearly 20 feet (6.1 m) rise. The two keys are the merging of two separate keys, which are combined when the channel is returned to accommodate changes to the crossing. The deepest "as-built" keys in the UK are considered Etruria Top Lock in Trent and Mersey Canal and Somerton Deep Lock on the Oxford Canal: both have an increase of about 14Ã, ft (4.3 m). Again, the sources vary for the deepest, and in any case Etruria has been deepened for years to accommodate the decline. The more typical increment (in the UK) is 7-12 feet (2.1-3.7 meters) (though more shallow can be found). By comparison, Carrapatelo and Valeira lock the Douro river in Portugal, which has a length of 279 feet (85 m) and a width of 39 feet (12 m), has a maximum lift of 115 feet (35 m) and 108 feet (33 m) respectively. The two keys of Ardnacrusha near Limerick on Shannon's navigation in Ireland have a 100 foot (30 m) rise. The upper chamber is up 60 feet (18 m) and is connected to the lower chamber by a tunnel, which when descended is not visible until the room is almost empty.
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A pound is the stretch water level between two keys (also known as reach ). On the American channel, a pound is called a level.
Chamber
The chamber is a key feature of a key. It is waterproof (brick, brick, steel or concrete) enclosures that can be covered from pounds at both ends by way of a gate. Space may be the same size (plus a bit of maneuvering space) as the largest drain designed drains; sometimes larger, to allow more than one such ship at a time to use the key. The space is said to be "full" when the water level is equal to the upper pound; and "empty" when the level is equal to the lower pound. (If the key does not contain water at all, it may be for maintenance work, may also be said to be empty, but more often described as "drained" or "water-eliminated".)
Cill
The cill , also spelled sill , is a narrow horizontal ledge protruding toward the room from below the top gate. Allowing the rear of the boat to "hang" on the cill is the primary danger warned to prevent when it goes down, and the front edge position of the cill is usually marked on the key side by white lines. The edge of the claw is usually curved, less prominent in the middle than at the end. In some locks, there is a piece of oak about 9 inches (23 cm) thick that protects the solid from the key rod. In the Oxford Canal it's called Babbie; on the Grand Union Canal, this is called the Bumper cill. Some canal operating authorities, especially in the United States and Canada, call the ledge as sill liter (partner sill in Canada).
Photo gallery
Gates
Gates is an impermeable door that closes space from the upper and lower pounds. Each end of the room is equipped with a gate, or a pair of half gates, made of oak or elm (or now sometimes steel). The most common setting, usually called the miter gate, was discovered by Leonardo da Vinci, around the 15th century. When closed, a pair meets at an angle like a chevron pointing upstream and only a small difference in the water level required to press the closed gate safely together. This reduces leakage from between them and prevents them from opening until the water level equalizes. If the room is not full, the top gate is secure; and if the room is not completely empty, the bottom gate is secure (in normal operation, therefore, space can not open at both ends). The lower door is higher than the top gate, because the top gate should only be high enough to cover the upper pound, while the lower gate should be able to close the full space. The upper gate at the canal is deep, plus a little more for the balance beam, the winding mechanism, etc.; The lower gate height is equal to the top gate plus lock key.
Balancing balance
A beam balance is the long arm projecting from the land side of the top gate towpath. As well as giving effect to opening and closing heavy gates, the beam also balances the gate load (which is not floating) in its socket, and allows the gate to swing more freely.
Paddle
A paddle - sometimes known as idlers , clough , or (in American English) wicket - is a simple valve where the key chamber is filled or discharged. The paddle itself is a sliding wood panel (or now plastic) which when "lifted" (slid) out of the way allows water to enter the room from the upper pound or flow to the lower pound. A paddle gate just covers the hole at the bottom of the gate; oars of more sophisticated soil block the underground culverts. There can be up to 8 oars (two paddle gates and two paddles of land at both the upper and lower end of the room) but there will be less. For a long time since the 1970s it was British Waterways policy not to provide gate paddles at the top gates of replacements if two paddles of land existed. The reason for this is given as salvation, because the ship may be climbed inundated by water from the raised gate carriage. However, without the gate handle, the padlock will be slower to operate and this has been blamed in some places for causing congestion. Since the late 1990s the preferred method is to maintain or reinstall the gate gates and install 'baffles' between them to minimize the risk of inundation.
In the old Erie Canal, there is the danger of injury when operating a paddle: water, when it reaches a certain position, will push the paddle with the force that can tear the tap (or grip) machine out of a person's hand, or if there is standing in the wrong place, channel, causing injuries and drowning.
Winding teeth or rowing teeth
Winding gear is a mechanism that allows the paddle to be lifted (opened) or lowered (closed). Typically, the stub section of the square appears from the winding tooth. This is the axis of the sprocket ("pinion") associated with the racking bar ("rack") mounted by the rodding to the top of the paddle. A key-guard or member of the boat's beach crew uses a square socket from their hoist machine (see below) to the end of the shaft and turns the trimmer machine it's probably a dozen times. It twisted the pinion and lifted the paddle. A pawl engages with a shelf to prevent the oars from falling accidentally while being raised, and to keep lifting when the tap engine is removed, so the operator can attend to other paddles. Currently considered unwise and wasteful of water to leave the paddle open after the boat left the key, but on commercial days it is a normal practice. To lower the paddle, the pawl should be removed and the paddle is wrapped around the winding machine. Dropping the paddle by tapping the pawet can cause damage to the mechanism; rowing teeth are usually made of cast iron and can break or crack when falling from a height. In areas where water-wastage due to vandalism is a problem, (eg Birmingham Canal Navigations), rowing mechanisms are generally equipped with evil-proof keys (currently recruiting "water conservation devices") that require the boater to use the key before the paddle can be lifted. Keys are officially known as "water conservation keys", but seafarers usually refer to them as T-keys , of their form; lock cuffs because the original key, installed in Leeds and the Liverpool Canal, is similar to handcuffs; Leeds and Liverpool Keys after the channel; or just Anti-Vandal Keys .
Hydraulic paddle
During the 1980s, the British Water Channel began introducing hydraulic systems to operate oars, especially those at the lower gate, the heaviest to operate. A single-foot diameter metal tube is mounted on the balance beam and contains a small oil-operated hydraulic pump. A spindle protrudes from the front face and is operated by a windlass in the usual way, the energy transferred to the actual oar by small pipes. The system is widely installed and in some channels it becomes very common. Apparently there are two serious flaws. It is much more expensive to install and maintain than traditional equipment and more often wrong, especially the vandals learn to cut pipes. Worse, he has a security flaw, that a paddle once in a raised position can not be dropped in an emergency, but must be stopped, take more. These factors led to the abandonment of policies in the late 1990s, but the examples persisted throughout the system, as they were usually not removed until the gates needed to be replaced, which occurred about every twenty years.
Windlass ("lock key")
A snail machine (also various 'key handles', 'iron' or just 'locks') is a removable crank that is used to unlock the lock (the word does not refer to the winding mechanism itself).
The simplest winding machine is made of iron rods from the circular part, about half an inch in diameter and two feet long, bent to make L-shapes with legs of slightly different lengths. 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 socket, sometimes tapered, with the right size to fit the spindle protruding from the key scrolling gear.
- Sockets: Traditionally, wind goggles have a single socket, designed for a particular channel. When traveling through multiple channels with different key-tooth spindle sizes it is necessary to carry several different windlasses. A modern glass screw machine usually has two sockets for use on different canals: the smaller is for the standard British Waterways spindle, mounted in the early 1990s almost everywhere, the bigger for equipment in the Grand Union Canal north of Napton Junction , which they can not/will not convert.
- Handle: The handle is long enough for the two-handed grip and far enough from the socket to provide enough leverage to roll the paddle up or down. There may be free-flowing sleeves around the handle to protect the hand from rough friction on the skin.
- Arm: The long throw has a longer arm so that the handle is further away from the socket to provide greater leverage on the harder paddle. If the throw is too long then the user, winding paddle gate, risks barking their knuckles against the balance beam when the handle is at the lowest point of its arc. Modern sophisticated cutting machines may have adjustable sleeves.
- Ingredients: Early glasses are individually forged from a piece of wrought iron by a blacksmith. More modern techniques include iron or bronze casting, forging and welding techniques (the most common techniques). Some boat drivers have silver (or chrome-plated) silver glasses to enhance comfort and prevent rust. Windlasses are now rarely gilded, but the popular modern choice of metal is aluminum, whose smooth and rust-resistant surfaces have the same longevity and blister reduction, and are also very light. One of these types, Dunton Double, has only one eye, but with an ingenious tapering it will operate both the size of the spindle.
At Chesapeake and the Ohio Canal, key guards are required to remove wind glasses from all locks at night, to prevent unauthorized use.
"Rotating" lock
"Rotating" the key can mean emptying the full key, or filling the empty one ("We entered the key, and it only took five minutes to change it"). This is used more often to refer to keys that are filled or emptied for the benefit of others ("The keys are reversed for us by a boat that comes in another way") and sometimes vice versa ("Locks are installed for us, but the coming crew another way to change it before we get there ").
Swelling or Swelling
A swelled is caused by the sudden opening of the paddle valve at the key gate, or when emptying the lock. To help the ship leave (downstream) the key, the locksmith will sometimes open the paddle to create big waves, which will help "flush" the boat out of the key. In one case, a boatman asked for big waves, that is, opened and closed the paddle several times to create waves, to help him out of the bank where he was trapped. If the ship ran aground (sometimes overloaded) they sometimes asked the passing crew to tell the upstream key to give them an extra large wave, consisting of opening all the paddles at the key gate, creating a spike affecting all the pounds below.
In the Erie Canal, some boats have the need to wave out of the lock, especially the wooden boat, which weighs above, will register to one side and get trapped in the hole, and need the waves to pull it out. Some key guards will have a big influence on anyone to help them on their way, but some will ask for money for the waves.
Erie Canal Management does not like swelling for two reasons. First, using too much water that lowers water on the pound above sometimes causes the ship to run aground. In addition, raising the water level at the pound below causes some boats to break down or freeze.
"Key mooring"
"Lock mooring" is a common method used to navigate to a lock by a barge traveling upstream. The barge will be directed to the sagging water to one side of the key gate and when the water volume decreases when the lock emptying the barge or boat is effectively sucked out of the sagging water to the key gate lane. The effort required to navigate the barge or boat to the key mouth is therefore substantially reduced.
Snubbing posts
On horse-drawn canals and donkey draws, insulting posts are used to slow or stop the boat in the lock. A 200-ton boat that moves several miles per hour can destroy key gates. To prevent this, the rope is wrapped around the post post when the boat enters the lock. Pulling the rope slows the ship, because the friction rope against the pole. A rope 2Ã,½ inch (6.3 cm) in diameter and about 60 feet (18 meters) long is usually used on the Erie Channel to snub a boat in the lock.
One incident, which occurred in June 1873 in Chesapeake and Canal Ohio, involved the ship of Henry C. Flagg and his drunken captain. The boat had leaked; the crew, after partially pumping water out, entered Lock 74, moving in front of another boat. Because they failed to steal the boat, it crashed and paralyzed the downstream gate. The flow of water from the lock causes the upstream gate to slam shut, violate them as well, and send the waterfall onto the boat, drowning it. This suspended navigation is on the channel for 48 hours until the lock gate can be replaced and the boat is removed from the lock.
Variations
Some keys are operated (or at least supervised) by professional key guards or volunteers. This is especially true of commercial waterways, or where the lock is large or has a complicated feature that the average passenger can not operate successfully. For example, although the Thames River above Teddington (England) is almost entirely a recreational waterway, the keys are usually managed. Recently there were seafarers allowed limited access to the hydraulic gear to operate the lock when the guards were absent.
- Powerful operation. In large modern channels, especially large ones such as ship canals, gates and oars are too large to be operated by hand, and operated by hydraulic or electric equipment. In the Caledonian Channel, the key gates are operated by a human powered capstan, which is connected by a chain to open the gate and the other to close it. In 1968 it has been replaced by hydraulic power that works through steel rafting. Even on smaller channels, some gates and oars are electrically operated, especially if the keys are regularly managed by a professional key keeper. On the Thames below Oxford all keys are managed and empowered. The powered keys are usually still filled by gravity, although some very large keys use the pump to speed up the work.
- Fish Ladder. The construction of locks (or weirs and dams) on the river precludes fishing trips. Some fish such as lamprey, trout, and salmon go upstream to lay eggs. Measures such as fish ladders are often taken to counteract this. The navigation key also has the potential to operate as a pathway to provide wider access to different biota.
- Weigh the key.
A weighing key is a dedicated channel lock designed to determine the weight of a barge to assess toll payments based on the weight and value of the cargo carried. The Erie channel has a weighing key in Rochester, Syracuse, and West Troy New York. The Lehigh channel also has a weighing key (see photo on the right).
Custom case
Lock flight
Loosely, the key flight is just a set of keys in close proximity to be identified as a group. For many reasons, the key flight is preferred over the same number of widely distributed keys: the crew is placed by the beach and picked once, rather than several times; transition involves an explosion of concentrated effort, rather than a continually disrupted journey; a lock keeper can be placed to help the crew through the flight quickly; and where water supply is limited, a single pump can recycle water to the top of the entire flight. Flight requirements may be determined purely by land lies, but it is possible to group keys intentionally into flight by using cuttings or embankments to "delay" altitude changes. Example: Caen Hill Key, Devizes.
"Flight" is not identical to "Ladder" (see below). A set of keys is just a ladder if the consecutive key chamber shares a gate (ie it has no top and bottom gates apart with a pound between them). Most flights are not stairs, because each space is a separate key (with its own top and bottom gates), there are pounds that can be navigated (however short) between each key pair, and keys operated in the conventional way.
However, some flights include (or consist entirely of) a ladder. On the Grand Union Canal (Leicester), the Watford flight consists of four-room staircases and three separate keys; and the Foxton flight is made up entirely of two adjoining 5-room chambers.
Staircase
Where a very steep gradient should be climbed, a key stair is used. There are two types of stairs, "real" and "clear".
The "real" ladder can be considered a "compressed" flight, where the medium pound has disappeared, and the upper gate of one key is also the bottom gate of one key above it. However, it is incorrect to use the terms ladder and flights alternately: in the absence of medium pounds, operating the stairs is very different from operating the flight. It would be useful to think of a ladder as a single key with a middle level (the top gate is the normal upper gate, and the intermediate gates are all at the bottom of the gate). Since there is no central pound, a room can only be filled by emptying the one above, or emptied by filling in the following: so the entire staircase must be full of water (except for the bottom space) before the boat starts up, or empty (except for the upper room ) before the boat begins to descend. By building a pair of sets of keys (used to climb and others to descend) these difficulties are avoided, as well as allowing greater traffic volumes and reduced waiting times.
In a "clear" staircase, the rooms still have common gates, but the water does not pass directly from one room to the next, but through a side pool. This means there is no need to ensure that the flight is full or empty before starting.
Examples of well-known "real" stairs in Britain are Bingley and Grindley Brook. The two ladder climbs are more common: Snakeholme Lock and Struncheon Hill Lock in Driffield Navigation are converted into ladder keys after low water levels inhibit navigation above the lower layers altogether but higher seawater - new bottom chamber rises far enough to get the boat on the barrel original key. In China, the newly completed Three Gorges Dam includes a five-step double steps for large vessels, and a vessel lifted for ships of less than 3000 metric tons. Examples of "clear" stairs are Foxton Locks and Watford Locks at the Leicester Branch of the Grand Union.
Stair operations are more involved than flights. Inexperienced seamen may consider operating a key ladder difficult. The main concern (whether it is paralyzed with indecision) either sending more water than the lower chamber can overcome (flood the towpath, or send waves along the canal) or completely empty the living room (although this indicates that the ladder key can be used as an emergency dock ). To avoid this accident, it is usual to have all the stairs empty before starting to go down, or full before the start up, regardless of the starting room.
One striking difference in using a ladder type (compared to a single key, or flight) is the best order to let the ship pass. In one key (or flight with space for the ship to pass) the boat should ideally alternate directions. However, on the ladder, it is faster for the boat to follow the previous one in the same direction. Partly for this reason the key ladders like Grindley Brook, Foxton, Watford and Bratch are supervised by the doorman, at least during the main roaming season, they usually try to take turns as much as the boat goes up, followed by down as there are rooms on the flight.
As with any flight, it is possible on a wide canal for more than one boat to be on the stairs at the same time, but managing this without wasting requires skill. On the UK canals, a staircase consisting of more than two rooms typically has staff: key guard at Bingley (keeping "5-up" and "3-up") ensuring that no undesirable events and that the boats are moved through as quickly and as efficient as possible. Such expertise allows the magic of a boat ballet: boats that travel in opposite directions can pass each other in the middle of the stairs by moving sideways to one another; or at peak times, one can have all the full space simultaneously with boats sailing in the same direction.
Double key, pair or twins
Keys can be built side by side in the same waterway. This is called doubling , pairing , or twinning . The Panama Canal has three sets of double keys. Doubling provides an advantage in speed, avoiding hold-ups at busy times and increasing the chances of finding a profitable key. There is also water savings: padlocks may have different sizes, so small boats do not need to empty large keys; or each key can serve as a water-saving basin for others. In the latter case, the word used is usually "twinned": here denotes the possibility of water savings by synchronizing the operation of the room so that some water from the emptying chamber helps fill the others. The facility has long been drawn on UK canals, although the unused rowing equipment can sometimes be seen, as in Hillmorton on the Oxford Canal. Elsewhere they are still in use; a pair of twin locks have been opened in 2014 at the Dortmund-Ems Canal near MÃÆ'¼nster, Germany.
The once famous staircase in Lockport, New York is also a double key. Five twin locks allow ships to the east and west to climb or descend Niagara Falls as high as 60 feet (18 feet), a considerable engineering feat in the nineteenth century. While Lockport today has two large steel locks, half the old twin stairs act as emergency levees and can still be seen, with the original lock gate restored in early 2016.
These terms may also be (in different places or for different people) means two-bedroom stairs (eg Turner Wood Double Locks at Chesterfield Canal: same channel has three steps up called Thorpe Low Treble locks), or just two flights key (as in Thornhill Double Locks on Calder and Hebble Navigation). Also, the "twin locks" (often less often, "twin keys") are often used by beginners in English channels to mean wide keys (14 feet), possibly because it "doubles" the width of the narrow lock, and allows two boats narrowly heading in the same direction to "multiply". It's really known as a broad key.
Stop locking
The "stop" key is a low-rise key built at the intersection of two canals (rivals) to prevent water from flowing between them.
During the competitive years of the British plumbing system, established channel companies often refuse to allow connections from newer and more contiguous. This situation created the Worcester Bar in Birmingham, where goods had to be moved between ships on rival channels just wide as feet.
Where the intersections are built, either because older channel companies see profits in connections, or where the new company succeeds in entering mandatory connections into the Parliament Act, the old company will seek to protect (and even increase) its water supply. Typically, they will determine that, at the intersection, the newer channel must be at a higher level than the existing channel. Although the decrease from the new to the older channel may be only a few inches, the difference in the level still requires a key - called stop lock , therefore to stop the continuous flow of water between the newer channel and the more old, inferior. The keys will be under the control of the new company, and the gateway, of course, "leads" upwards - towards the newer channel. This will protect water supplies from newer channels, but will still "donate" locked water to an older company each time a boat passes. At the time of excess water, of course, the "bywash" key will continue to supply water to the lower channel.
When a variable condition means that higher water levels in the new channel can not be guaranteed, the older company will also establish a stop lock (under its own control, with the gateway pointing to its own channel) which can be closed when the new channel is low. This produces a pair of consecutive keys, with gates pointing in opposite directions: one example is at Green Hall near Kidsgrove, where the southern end of the Macclesfield Canal joins the Green Branch Hall of Trent and the earlier Mersey Canal. The four-gate stop near Kings Norton Junction, between Stratford-upon-Avon Canal and Worcester and the Birmingham Canal was replaced in 1914 by a pair of key guillotine gates that stopped the flow of water regardless of which canal was higher. This gate has been permanently opened since nationalization.
Many key stops have been deleted or converted to a single gateway after nationalization in 1948. Hall Green stops fixed keys, but as a single key: additional keys have been removed due to a decrease in T & amp; M's summit pound (to increase the air of the Harecastle Tunnel) draft "- high freely above water level" means T & amp; M will always be lower than Macclesfield. The Hall Green Branch is now considered an extension of the Macclesfield Canal, which now meets T & amp; M at Hardings Wood Junction (just short of the northern portal of Harecastle Tunnel).
It should be noted that newer channels are not always at a higher level than the joining channels. For example, there is a very shallow lock in Autherley Junction, where 1835 Birmingham and the Liverpool canal (now part of the Union Shropshire Canal) meet with Staffordshire and the older Worcestershire Channel, built in 1772. Nicholson's guide shows that a rower goes south along new channel locks "go up" before turning north or south to Staffordshire and the older Worcestershire Channel - so the Shropshire Shore Canal gets a small water key each time a boat passes by. However, the advantage is small because the level difference is so small that it can sometimes open both gates at once.
round key
There are instances where keys have been built for circular plans, with more than two exits from the key chambers, each serving different water levels. So the key works well as how to change the level and as the intersection. The circular plan of the key allows the boat inside to rotate to line up with the appropriate exit gate.
The best example of a round key like this is the Round Lock Agde on the Canal du Midi in France. It serves as a key on the main channel path and allows access to the HÃÆ' Â © rault River.
The second French spin lock can be found in the form, now unused, ÃÆ' â € ° cluse des Lorraines, connecting the Canal latÃÆ'Â © ral ÃÆ' la Loire with the Allier River.
Drop lock
A drop key allows a short channel to be temporarily lowered while the boat passes under a barrier like a low bridge. During channel restoration, drop keys can be used where it is impractical or very expensive to remove or raise structures built after the channel is closed (and where channel re-routing is not possible).
A drop key can consist of two conventional key chambers leading to the pound, or a single long space that combines sumps - although the term only applies to the second case. Since the pounds at both ends of the structure have the same height, the keys can only be emptied by allowing the water to flow into the waste from the heap to the lower stream or channel, or (less wasteful) by pumping water back into the canal. Particularly in the two-chamber type, there will be a need for a culvert cut, to allow the water to move along the broken pound and thus supply the lock further down the channel. In the case of a single-room type, this can be achieved by keeping the key fully locked and leaving the gates open when not in use.
While the concept has been suggested in a number of cases, the only examples in the world of key drops that have actually been built are in Dalmuir at Forth and Clyde Canal in Scotland. This key, of a single type of space, was inserted during the restoration of the canal, to allow replacement of the swing bridge (on busy A road) by a fixed bridge, and responded to criticism that channel restoration would lead to frequent interruptions of heavy road traffic. This can be emptied by pumping - but because it uses a lot of electricity the method used when an adequate water supply is to drain the key to the nearest burn. A series of images showing the operation of the key can be seen here.
Flood lock
A flood lock is to prevent the stream from flooding the connected waterway. Usually installed where the canal leaves the river. At the normal river level, the lock gate is left open, and the channel height is allowed up and down with the height of the river.
However, if a river floods outside the safe boundary for the canal, then the gate is closed (and an additional key is made) until the river descends again. Since this is the correct key it is possible for the ship to leave the canal for the flooded river despite the difference in water level (though this may not be wise) or (more sensible) to allow the ship to be caught in the flood to get sheltered in the canal.
Note that if the channel is just a navigation snippet connecting two strands of the same river, the flood lock will be at the upstream end of the piece (the downstream end will have a conventional key).
Flood keys that have been used only as flood gates (see below) are often unable to return to their original destination without repair. That is, where only the outer gate is ever closed (perhaps because the waterway is not the correct commercial place, and therefore there is no financial necessity for the vessel to exit to the flooded river) the inner gate soon suffers due to lack of maintenance. A good example is on Calder and Hebble Navigation, where the structure mentioned in boating guides as "Flood Keys" is clearly only capable of being used for flood prevention, not for "writing" boats to or from rivers in floods.
Flood gate
A flooded flood gate or a stop gate is a cheaper equivalent of a flood lock. There is only one set of gates, so when the river is higher than the canal, the gate is closed and the navigation stops. This is very common in the French outpost system. Flood gates can also be used to distribute pounds of waterways or protect, in the event of a bank collapse, the surrounding area if this is lower than the water level. They are commonly found at the ends of long dikes and in waterways. These gates are often overlooked because they lack the balance beam and are only slightly higher than normal channel levels.
Two-way gateway and lock
Where the key is the ups and downs (ie one side of the key has varying levels of water with the tide) or where the channel meets the varying rivers, water on the tidal or river side (downstream side) may rise. on the water on the "top" side of the normal. The "upstream" pointing door will fail to do its job, and it will only open. To prevent water from flowing in the wrong way through a lock, at least there should be a set of gates pointing in the "wrong" direction. If it is desired that the boat can use a lock under these circumstances, then there needs to be a set of gates that lead to the tidal or river side. The usual method is to have gates pointing in opposite directions at either end of the space (or, the arrangement of "paired paired keys" of two separate sequential keys pointing in the opposite direction will work here - but will require additional space). If navigation is not necessary (or impossible) on an "extreme" (eg Allowing navigation above mid-tide, but only preventing empty channels during low tide) then it only needs to have a set of two-way gates.
The sea key is the key that connects the canal or river directly with the estuary or ocean. All tidal sea locks.
Tidal lock
The plugs are generally the key that connects the tide with non-tidal water. These include locks between tidal and tidal streams, or between tidal and canal streams, or sea locks. However, this term usually refers to a key whose method of operation is affected by the state of pairs. Example:
- The channel joins a stream that is always lower than the channel. All that's required is a regular key, with a gateway pointing to the channel. The key is usually used during high tide to float the ship through the bottom gate. If the receding water near the key becomes unusable, then the gate can be prohibited (and only the "reverse flood gate", holding the water in the canal). This setting also applies to some marine keys (eg Bude Canal).
- The channel joins the normally underlying river, but that can rise above it (when the water is very high, or after heavy rains). A pair of gates can be made in both directions, ie the gate pointing in will be fitted with a pair pointing to the river. When the river is higher than the canal, the normal gate will only float open, but a pair of additional gates can be closed to protect the canal, and prevent navigation to the river. Actually, we just added flood gates.
- As above, but where it is safe to navigate even when the stream is higher than the channel . The keys will be fully bidirectional (two pairs of opposing pointed gates at each end) to allow the boat to pass at any normal river level. At low or low extreme lows that are not suitable for navigation, the appropriate set of gates is forbidden to pass.
Inlet Lock
The key of the inlet is to regulate water from the feeder channel or stream to the main channel. In some cases, the incoming channel key may double as a lifting lock to allow the ship to enter a sagging river. Notice that in the example to the right, the feeder channel was originally the George Washington Waterfall Red Cross which is part of the Potomac Company channel, which is then recreated as feeder channel for Chesapeake and Ohio Channel.
Very large key
The biggest key in the world is, until 2016, the Berendrecht Key, giving access to the Port of Antwerp in Belgium. In 2016, Kieldrechtsluis at the same port became the largest. The lock is a length of 500 m (1,600 ft), and 68 m wide (223 ft) and down 17.8 m (58 ft), and has four sliding key gates. Key sizes can not be compared without considering the different water levels designed to operate below. For example, the key BollÃÆ'¨ne on the RhÃÆ'Â'ne River has a fall of at least 23 m (75 ft), Leerstetten, EckersmÃÆ'¼hlen and Hilpoltstein lock on the Rhine-Main-Danube Canal having fall of 24.67 m (80.9 ft), respectively and the Oskemen Lock in Irtysh River in Kazakhstan has a drop of 42 m (138 ft). The total volume of water to be considered in each key is equal to the product of its length, width and water level difference. Key ladders are used in an effort to reduce the total volume of water required in relation to the amount of useful work performed. Useful work is done in relation to the weight of the ship and the elevated elevation. When a ship is lowered the potential energy consumption of the consumed water is considered. The alternative to keys is the boat lift; this type of facility, e.g. Anderton boat lift or lift boat StrÃÆ' Â © py-Thieu in Belgium, does not rely on water consumption as the main power source, powered by motor and designed to consume water in minimum quantities.
29 keys on the Mississippi River are usually 600 feet long (180 m) long while the pull and barge combinations are as many as 1,200 feet long (370 m) long which consists of as many as 15 barges and one pull. In this case, some barges are locked, using a partially opened lock valve to create a current to pull a barge that is not powered out of the lock where they are tied to wait for the rest of the barge and pull to pass through the key. It can take up to an hour and a half to pass the key.
The Guillotine key gate works in a similar way to a water gate, but most channel lock gates are hinged to swing like doors.
Hiram M. Chittenden Key
Every November, the big keys of Hiram M. Chittenden Lock (locally known as "Ballard Locks" referring to the Seattle neighborhood they are in) are emptied for maintenance, as seen in the November 2004 picture below. This provides an opportunity to visualize how the key works without water obscure the bottom of the key. For reference, the leftmost image shows the key in operation, with tug and barge (loaded with sand and gravel) waiting for the gates to open. In the bottom left corner of the picture can be seen cut-out on the side wall that contains the gate when it opens.
The lock has three pairs of gates, one pair at each end and one pairs in the middle so half the key length can be used when the entire length is not needed, thus saving water. The barely visible person walking along the bottom of the key in the second picture gives an indication of the size of this key. On both images of the final gate, a series of penstock openings are visible along the sides at the bottom. The water entering and leaving the key flows by gravity through these holes. It takes about 15 minutes to charge or clear the key.
Van gate
This type of gate was a Dutch invention in the early nineteenth century. Van Gate has a special property that can be opened towards high water using only water pressure. This type of gate is mainly used to flood certain areas, for example in the case of the Dutch Water Line. Currently this type of gate can still be found in some places, for example in Gouda.
The design of the Van gate is shown in the picture at the bottom right. When the pipe connecting a separate space with the high water side of the water gate is closed and the connection with the low water level side is opened, the water level in the separate chamber will descend to the level at the low water side of the sluice gate.. The surface area of ​​the gate separating the space from the high side of the water from the gate is greater than the gate that closes the floodgates. This produces a total force that opens the floodgates.
History and development
Dams and weirs
In ancient times river transport was common, but rivers were often too shallow to carry anything but the smallest boats. Ancient people found that rivers could be made to carry larger boats by making dams to raise the water's surface. The water behind the dam becomes deeper until it spills over it forming a weir. The water is deep enough to carry a larger boat. The dam building is repeated along the river, until there is a "rung" of deep water.
Flash Key
The development of dams and weirs creates the problem of how to get a boat between "steps" of water. The initial and rough way to do this is with a flash key. The flash key basically consists of a small hole in the dam, which can be opened and closed quickly. On the Thames River in England, these are closed with vertical posts (known as rymers) where boards are placed to block gaps.
When the gap is opened, a spray of water will spill out, bring a boat "downstream" with it, or let the boat "headwaters" to become humans being transported or beaten against the tide. When the ship is over, the opening will soon be closed again. "Gate" can also be opened to release the 'flash' downstream to allow the grounded boat to exit the shelf, hence its name.
This system is used extensively in Ancient China and in many other parts of the world. But this method is dangerous, and many boats are drowned by the flow of water. Because this system needs to lower the rate in pounds, it is unpopular with factories that rely on full heads of water to operate their equipment. This leads to continuous fighting, both legal and physical, between navigation and grinding interests, with rivers closed for navigation if there is water shortage. It was primarily this conflict, which led to the adoption of the pound key in medieval China, since this meant that relatively little water was consumed by navigation.
Staunch
A more sophisticated tool is a water gate or staunch, which consists of a gate (or a pair of mitred gates) that can be closed and closed by water pressure when the river is low, to float the ship over shallow water when low. However, the entire head of the upstream water should be dried (by some additional methods approaching the modern water gate) before a boat can pass. Thus, they are not used where the obstacles to be traversed are plant weirs.
Pound lock
The natural extension of the firm is to provide the top gate (or pair of gates) to form a medium "pound" which all needs to be emptied when a boat passes through it. These key types, called pound keys are known in Imperial China and Europe.
The Pound Key was first used in medieval China during the Song Dynasty (960-1279 AD). Songshi or Song Dynasty History, volume 307, biography 66, notes how Qiao Weiyue, a high-level tax administrator, feels frustrated at the frequent disadvantages when his barley tank is damaged in the West River near Huai'an in Jiangsu. The soldiers on a ship's slip, he discovered, had planned with bandits to destroy the heavy imperial barge so they could steal the spilled grain. In 984 Qiao installed a pair of water doors two hundred and fifty feet apart, the entire roof structure like a building. By placing two adjacent gates to each other, Qiao has created a short channel stretch, effectively pound key, filled from the above channel by lifting individual wooden beams at the top gate and emptied into the canal below by lowering the baulks at the top gate and lift the one below.
Turf-side locking
Side turf keys are the earliest form of key channel design that uses the earth banks to form key chambers, then attract grass and other vegetation, rather than the now widely known and widespread brick, stone, or concrete wall construction. These early key designs were most commonly used in river navigation in the early 18th century before the advent of canals in England. The sides of the pad are shifted so that, when full, the keys are wide enough. As a result, this type of lock requires more water to operate than a brick or vertical walled stone. In British channels and water channels, most of the key-sides have been rebuilt in brick or stone, so only a few good surviving examples, such as in Garston Lock, and Monkey Marsh Lock, on Kennet and Avon Canal.
Water usage
A key problem caused by a key is that, each time a key passes through one empty-charge cycle, a water lock (tens of thousands to millions of liters) is released to the lower pound. In simpler terms, on a canal where only one boat will fit a key, a boat traveling from the top of pound to the lowest pound is accompanied on its journey with a locked 'private' water. A boat headed in the other direction also removes the water that is locked from the peak to the lowest pound. To prevent dry channels, several methods should be used to ensure that the water supply at the top of the canal is constantly replenished with a dried down water rate. This is, of course, more trouble with artificial channels that cross the watershed than river navigation.
Design
When planning a channel, the designer will seek to build a peak level with a large reservoir, or supplied by an artificial drain from a distant source, or one as long as possible (to act as its own reservoir) or cut as many springs or rivers as possible (or All of these). Driving the peak level through deep cuts or tunnels can cut through water tables as well as underground water sources.
Pumping
Where it is clear that the natural supply will not be enough to fill the peak level at the level that the water will be used (or to allow an unexpected drought period) the designer can plan the water to be re-pumped back to the top from bottom to bottom. Such restoration can of course be installed later, when bad planning becomes apparent, or when there is an unexpected increase in traffic or scarcity of rain. On a smaller scale, some local pumping may be needed at certain points (water continues to be recycled through some locks on Kennet and Avon canals).
Water-saving holder
The way to reduce water used by a key is to give one or more reservoirs, which are between the upper and lower pounds. These reservoirs can store water flowing from a key when a boat goes down, and release it to fill in the next time when a boat goes up. This saves half the amount of water lost in each empty charging cycle. Generally this reservoir is called "save basin".
Installing one side of the pool will save 1/3 of water, while the three sides of the pool will save 60% water: the first 1/5 of water goes into the upper pool, 1/5 to the middle pool, 1/5 to 3 to the bottom of the pond - and 2/5 wasted in each section (assuming the area of ​​each pool is the same as the key area). The formula for the side pool of height and optimal depth, with the area of ​​each pool, , and the key area, , are:
Source of the article : Wikipedia
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