1、英文文献翻译 The Two LuCable Cranes General Description The 2 luffing cable cranes are destined for the construction of the Three Gorges Dam in the valley of the Yangtze River. The jobsite is situated near Sandouping, Yichang in the province Hubei in the Peoples Republic of China. The cable cranes, repres
2、enting the main transport facility of a dam construction jobsite, have been designed for the purpose of transporting concrete, formwork items, concrete pre-fabitems, reinforcing material, building machinery and machine components such as penstocks, generators, lock gates, etc. . The cable cranes tha
3、t will be used on the jobsite are of the luffing type, i. e. it has been given that name because for moving the track rope, the towers or masts one have to luff to the upstream or downstream direction. Both the slewing masts of each single crane between which the track ropes are installed, are situa
4、ted -at an elevation of + 185 m on block 8 already concreted on the left bank and on the longitudinal coffer dam at the elevation of + 160 m. Each mast has a height of 125 + 25 = 150m, and is firmly anchored by rear stay ropes in longitudinal direction. On their sides, the masts are held respectivel
5、y moved by 6-strand luffing ropes actuated by winches. The spans are: Rear stay ropes on the left bank approx. 270m Rear stay ropes on the right bank approx. 604.5m. Track ropes: approx. 1416m The machine houses for the winches of the cranes are arranged on the foot of the masts. In the machine hous
6、es on the foot of the head towers are arranged the winches for hoisting crab traversing and mast luffing. In the machine houses on the foot of the tail towers are only situated the winches for mast luffing . This machine houses are therefore called luffing winch house . The control electronics are e
7、ach located in separate rooms, for thus avoiding any problems as might occur by dust or also temperature variations. There are three possibilities to control the winches. Normally the crane is controlled by the drivers cabin that is movable between the machine side and the counter side on a long cab
8、le. The second way is to control the cable crane by a -wireless portable control unit. For each crane there is one mobile unit. The third possibility to control the winches is the local control device nearby the machines for the hoist, crab traversing and luffing systems . The local control device i
9、s for purpose of easy adjustment and repairing. Because of the local situation, there are certain areas of the working field with obstacles. These areas are locked by the programmable computer control system. For the control systems see also the Electrical documents of ABB Company. The crab traversi
10、ng winch is driven by a DC-motor that allows for an infinitely variable speed regulation. For physics reasons he acceleration shouldnt be much beyond 0. 75 m/s2 . Thereof result acceleration and braking times of approx. 10 seconds (braking torque about 6000 Nm) ； respective path is approx. 37:5m. Wi
11、th commissioning operations the mechanical brake shall be set in a way that the loaded crab will come to be stopped after at the latest 12 seconds (braking torque approx. 6000 Nm). Because of the varying loads will result otherwise with merely mechanical braking (emergency) shorter braking times. No
12、rmally the torque having been generated by the motor is transmitted over a 2-groove drive pulley to the crab traversing rope. Here one has to check periodically for ensuring-an uniform running in the two grooves (see chapter Maintenance). Between the two grooves the crab traversing rope is led over the return pulley； at the shaft of which is also fitted :the
