Wednesday, 10 November 2010




Scraper is heavy equipment that to dredge up, transport and scatter land/ground of dredging result in endues. Scraper can be implementational transportation to apart that relative far (2000 m) at plain with activator tyre wheel. Election scraper for this job depend on :

1). Significant Characteristic operated
2). Panjng travelled distance
3). Street Condition
4). Networked Tool

Scraper are classified base its type, scraper pulled (tower scraper), scraper motorizes (motorized scraper), and scraper that content by it self (self loading scaper). Towed scraper are generally pulled crawler tractor with machine strength 300 hps or more. Scraper this type of can accomodate significant 8 – 30 m3s.

A. Operation Scraper
Scraper consist of some parts for example bowl, appron, and tail gate. Bowl is payload receptacle lay betweens back tyre. Frontage bowl can move downwards to operate for dredging and cargo discharging. At front side part bowl ranges from 3 till 38 m3s
Appron is wall bowl frontage that can be lifted when dredging and unloading. Appron can close returned when significant transportation. Some models scraper have appron that can transport significant one-third from significant in bowl.
Tail gate or ejector is back wall bowl. When this loading and transportation of wall significant motion less. Nevertheless when ejector cargo discharging moves forward to push significant exits from bowl.
Tool operation is used with two ways :
1). Push-loaded. Tool are weared only at dredging moment and admission filling.
2). Push pull. Two units scraper are operated by this way its second each other help didalam dredging. Scraper is behind pushed scraper didepannya when dredging and interesting scraper didepannya scraper that behind when dredging.

B. Productivity Scraper
Productivity sraper depend on significant type, energy to transport, street condition, speed lat, tool efficiency. Significant Volume that will be moved will influence capacities scraper selected. Whereas transportation amount per hour depend on cycle time scraper.
Cycle Time merupan addition from time load (LT), transportation time (HT), Cargo Discharging Time (DT), Time Return (RT), and time queues up (ST). in other hand there is rotary time or turning time (TT) and acceleration time, deceleration and braking or accelerating, decelerating and braking time (ADBT). Because LT, DT, ST, TT and ADBT consistence then times are referred categorized as time fixed (FT) see table 1. until formula that weared is

FT = LT + DT + ST + TT + ADBT

Tables 1. Value FT (minute)

Note : 1 = good condition
2 = condition
3 = ugly condition

C. Pusher (Impeller Tool)
Tool Usage or pusher at scraper in its operation can boost up tool productivity. Cycle Time pusher is time that required to load significant into scraper added time that required pusher to move from one scraper to other scraper. Cycle Time (in minute) looked for by using formula :

CTp = 140% x LTs + 0,25

Amount scraper that can be helped by a pusher is :

N = CTs/CTp

D. Improvement Productivity Scraper
Some implementable way to increase product scraper in its operation for example :
1. First by scarify that will be loaded into bowl. That is time load will decrease. Penetration Deepness from riper should be able to be big from penetration deepness cutting edge.
2. By wett land/ground that will be transported. Conducted before loaded into bowl
3. Load significant at downhill condition also is one of way to increase product.

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