1、1 本科毕业设计（论文） 外文资料及翻译 年 级 : 2007 级 学 号 : 20077657 姓 名 : 专 业 : 工程机械 指导老师 : 2011 年 5 月2 Loading machines For materials handing in construction,use is made of loaders.Practice has shown that excavators are less effective in the capacity of loads in quarries and storages of nonmetallic materials than loa
2、ders. By the kind of loads handled,loaders are classified as forklift loads and scooping loaders for loose materials.Sooping loaders are divided into single-bucket and continuous-action Multi-bucket loaders.Single-bucket loaders are general-purpose machines suited engineering and in applications req
3、uring continuous working process. Depending on the kind of running gear,crawler and anailable.Crawler loaders have a high passblibity and develop a great thrust efftort. Wheeled loaders feature a high manoeuvrability and high traveling speeds making no damage to the road pavement and the storage are
4、as. Unloaders are used for unloading sand, gravel, crushed stone, cement form railway cars. Power and pneumatic unloaders are used,power for unloading materials from flat cars or gondola cars(open wagons)and pneumatic for unloading cement. The main working member of fork-lift loaders is the fork ser
5、ving to load and unload piece loads. These loaders have different change attachments. When equipped with buckets or grabs, they are used for loading loose and small-piece materials, and the boom attachment makes these loaders suited for hoisting loads to a small heighe and sometimes for erection wor
6、k in construction. Fork-lift loaders are operated on hard-pavement areas,therefore they are mainly used in storehouse and as factory materials-handing equipment.They are made on the basis of a truck therefore they are also called truck loaders.they are powered by internal combustion engines or elect
7、ric motors with storage batteries. Engine powered truck are used for large warehouse and stock-handing application, for general yard work and fpr loading and unloading of vehicles. Torque converter transmission provides smooth operation； power steering and all-weather cabs are options available. 3 S
8、ingle-bucket loaders have a crawler tractor or a wheeled truck as a carrier mounting. The loader permits mechanization of loading construction and erection and work with the aid of change attachments,of which the main one is the bucket. The loading equipment is available in three modifications: fron
9、t-end,overloading, and half-swing,jib-type. The front-end attachment provides also side unloading.The overloading modifiactaion permits back unloading. Presently front-end loader with the positive displacement hydraulic drives for the attachment are most widely used. The output of multi-bucket loade
10、rs is 40 to 60 percent higher than of single-bucket machines at the same power rating,it is expedient to use them in brickyards,prefabricated concrete products plants,railway stations with large volumes of loading-unloading operatins and also for loading loose materials.In addition,they are suited f
11、or size grading of loose materials,for which purpose they are provided with special vibrating screens. Multi-bucket loaders are very efficient in unloading flatcars with side dumping of the handle material.These loaders can be applied in the production lines of prefabricatde ainstruction products pl
12、ants and also in road building.In the latter case they are used for loading sand and gravel into drying drums and mixers. The working member of the loader is a screw feeder consisting of tow right-hand and left-hand screws,which are arranged on both sides of a bucket elecator.When the feeder rotates
13、,the loaded material is delivered to the buckets to make the scooping easier.A scraper is secured underneath the screw feeder.The elevator of the multi-bucket loader usually dischanges the material onto belt conveyers that deliver it to tiansport facilities. Some loaders discharge the handle material into tranport facilities through hoppers or chutes.
