The first shipping lock, which was carried out alternating the alignment of the water level, was invented by Qiao, Value 984 year and built on the Great Chinese channel. The gateway was a straight section with a length of 76 meters, which was bounded on two sides by a gate. They were made of wooden boards and moved vertically. The coast gateway was strengthened, and over it was placed a canopy. During the 11th century the builders erected the gateways along the entire length of the Grand canal of China. How does the modern shipping gateway? This was in today’s issue!
So, the gateway is a hydraulic structure on navigation and waterways, which ensures the transfer of ships from one water basin to another with different levels of water in them. On both sides of the gateway are restricted by gates or gates, between which is a sealed chamber with adjustable water level. Camera any gateway has dimensions sufficient to contain one or more vessels. Thus, unlike slipways, gateway camera cannot change its position or dimensions. However, the level of water in it can change.
The gates are metal shields located at both ends of the camera. They are used for transmission and discharge of vessels and seal the chamber during the transfer of ships. In approach channels are provided with a safe environment for the movement and berthing of vessels at the quay walls.
One of the most important in the design of gateways is the tap device. It is designed for filling and emptying the chamber. Typically, this device uses flat panel shutter. At major gateways can be used special pumps.
The principle of operation of the gateway is as follows: first, open the entrance gate and the ship goes inside the camera and is moored to the bollards. Then the entrance gate is closed, and opens the bypass valve, causing the fall or rise of the water level in the chamber with her ship. This is achieved by transfusion or by pumping the water from an adjacent tank in the direction of the route of the vessel. When the water reaches the required level, equal to that available for the output of the gate cameras, the gate opens and the ship comes out of gateway.
The process of passing a vessel through the gateway lasts usually from 10 to 20 minutes depending on the size of the camera and the water level difference. When locking alternate the direction of transmission of the vessels: after the vessel proceeding downstream has completed the lockage, in a cell with already low level of water enters the ship moving in the opposite direction. Thus it is not necessary to do unnecessary filling or draining the water from the chamber.
If necessary to overcome a significant pressure differential or water build multi-gateways. They consists of several successive gateways. In this case, the ship is moved alternately along the chain of cameras. In China, the world’s largest hydroelectric Three gorges dam built five-chambered gateway. And in the UK on channel Avon built a 16-chamber! These gateways are called “ladders”.