《塔式起重机英文简介》由会员分享，可在线阅读，更多相关《塔式起重机英文简介（6页珍藏版）》请在金锄头文库上搜索。
1、Tower crane 1.Introduction to How Tower Cranes Work Tower cranes are a common fixture at any major construction site. Theyre pretty hard to miss - they often rise hundreds of feet into the air, and can reach out just as far. The construction crew uses the tower crane to lift steel, concrete, large t
2、ools like acetylene torches and generators, and a wide variety of other building materials.When you look at one of these cranes, what it can do seems nearly impossible: Why doesnt it tip over? How can such a long boom lift so much weight? How is it able to grow taller as the building grows taller? I
3、f you have ever wondered about how tower cranes work, then this article is for you. In this article, youll find out the answers to all of these questions and more! 2. Part of the tower crane All the tower cranes, including some of the same: Base is bolted to the large concrete pad to support crane.
4、Base connected to the mast (or tower), gives the tower crane with high explosive. Attached to the top of the mast is rotating units - gear and sports - to allow crane rotation: Slewing bearing units are on top of three parts: Long horizontal arm (or work institutions), which is part of the crane to
5、carry the load. Trolley along the boom in and out of mobile cranes load center: The level of short mechanical arm, which contains electrical and electronic crane and a large concrete counter weight: Operating room Robot contains motor, make the load, with control electronics to it with cable drum, a
6、s shown: Motor-driven rotary gear unit to the location of a large unit of the leaders of more than Now lets find out how much weight this device can handle. 3.How Much Weight Can They Lift?A typical tower crane has the following specifications: Maximum unsupported height - 265 feet (80 meters) The c
7、rane can have a total height much greater than 265 feet if it is tied into the building as the building rises around the crane. Maximum reach - 230 feet (70 meters) Maximum lifting power - 19.8 tons (18 metric tons), 300 tonne-meters (metric ton = tonne) Counterweights - 20 tons (16.3 metric tons) T
8、he maximum load that the crane can lift is 18 metric tons (39,690 pounds), but the crane cannot lift that much weight if the load is positioned at the end of the jib. The closer the load is positioned to the mast, the more weight the crane can lift safely. The 300 tonne-meter rating tells you the re
9、lationship. For example, if the operator positions the load 30 meters (100 feet) from the mast, the crane can lift a maximum of 10.1 tonnes. The crane uses two limit switches to make sure that the operator does not overload the crane: The maximum load switch monitors the pull on the cable and makes
10、sure that the load does not exceed 18 tonnes. The load moment switch makes sure that the operator does not exceed the tonne-meter rating of the crane as the load moves out on the jib. A cat head assembly in the slewing unit can measure the amount of collapse in the jib and sense when an overload con
11、dition occurs. Now, it would be a pretty big problem if one of these things fell over on a job site. Lets find out what keeps these massive structures standing upright. 4.Why Dont They Fall Over?When you look at a tall tower crane, the whole thing seems outrageous - why dont these structures fall ov
12、er, especially since they have no support wires of any kind? The first element of the tower cranes stability is a large concrete pad that the construction company pours several weeks before the crane arrives. This pad typically measures 30 feet by 30 feet by 4 feet (10 x 10 x 1.3 meters) and weighs
13、400,000 pounds (182,000 kg) - these are the pad measurements for the crane shown here. Large anchor bolts embedded deep into this pad support the base of the crane: So these cranes are essentially bolted to the ground to ensure their stability. In the next section, youll learn how tower cranes “grow
14、.“ 5.How Do They Grow?Tower cranes arrive at the construction site on 10 to 12 tractor-trailer rigs. The crew uses a mobile crane to assemble the jib and the machinery section, and places these horizontal members on a 40-foot (12-m) mast that consists of two mast sections. The mobile crane then adds
15、 the counterweights. The mast rises from this firm foundation. The mast is a large, triangulated lattice structure, typically 10 feet (3.2 meters) square. The triangulated structure gives the mast the strength to remain upright. 6.To rise to its maximum height, the crane grows itself one mast sectio
16、n at a time! The crew uses a top climber or climbing frame that fits between the slewing unit and the top of the mast. Heres the process: The crew hangs a weight on the jib to balance the counterweight. The crew detaches the slewing unit from the top of the mast. Large hydraulic rams in the top climber push the slewing unit up 20 feet (6 m). The crane operator uses the crane to lift another 20-foot mast section into the ga
