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Introduction to Civil & Mining Engineering Materials Handling - Earthmoving Scrapers Open Bowl Scraper Model 631G 336 Kw 23.7 m^3 heaped capacity 34 tonne rated load The Scraper • The scraper is a self-loading, transporting and spreading machine. • Used on projects such as road and airport runway construction, for distances < 3km • Essentially the earth is cut & loaded directly into the scraper box or bowl, transported to the discharge area and finally spread in layers. The process is a continuous cycle • Towed & motorised scrapers available dependent on the project size Excavating Action • Cutting the bowl is lowered and apron opened. • Forward movement, soil cut boils upwards into the bowl. Key to diagram:- • Approx 50-100m of travel 1 Apron is reqd. to fill the bowl 2 Bowl cutting edge 3 Ejector plate • Excavate in layers 150 - 300mm in depth • Discharge occurs on the Tractor pulled scrapers 8-30m^3 run, height of bowl set Motorised scrapers 15-5-m^3 • Ejector plate pushes the heaped capacities. soil out Motorised Scraper Cat 613C Elevating Scraper 131 kW flywheel power 8.4m^3 heaped 27t loaded 12t tare Max speed 35 kph in 6th. gear Motorised Scraper •The scraper frequently requires pushing assistance during the loading phase, because of loss of traction •Haul speeds of up to 60km/hr are possible on well graded roads •Capability example, 20m^3 heaped bowl capacity over 1km haul distance outputs of 150m^3/hr is possible •The larger scrapers up to 50m^3 capacity may be equipped with 1 or 2 large diesel engines up to 380kW each http://www.terex.co.uk/TS14G.pdf Motorised Scrapers • Standard single engine scraper • Double engine scraper • Four wheeled tractor scraper • Self-loading scraper Output of Motorised Scrapers Ideal output of the motorised scraper
"Introduction to Civil Mining Engineering"