CPEM Chapter 8--Scrapers

CPEM Chapter - SCRAPERS The Fresno Scraper Invented in 1883 A NATIONAL HISTORIC MECHANICAL ENGINEERING LANDMARK www.asme.org/history/brochures/h158

Info iconThis preview shows pages 1–9. Sign up to view the full content.

View Full Document Right Arrow Icon
11/27/2008 1 SCRAPERS Invented in 1883 A NATIONAL HISTORIC MECHANICAL ENGINEERING LANDMARK The Fresno Scraper www.asme.org/history/brochures/h158.pdf APPLICATIONS Dozer: short haul, less than 300ft Scraper: medium haul up to 3,000 ft APPLICATIONS Shot Rock Ripped Rock Earth/Rock Mix Zone of application Gravel Sand Silt Clay
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
11/27/2008 2 CONFIGURATIONS Conventional (push-loaded) Single engine CONVENTIONAL Conventional (push-loaded) single engine scrapers become uneconomical when uneconomical when: Haul grades > 5% Return grades > 12% CONFIGURATIONS Elevating CONFIGURATIONS Elevating scrapers are good for short hauls and in favorable material. Can work alone in the cut. Cost more initially & to operate Elevator adds weight & takes power.
Background image of page 2
11/27/2008 3 CONFIGURATIONS Tandem powered Engine CONFIGURATIONS Tandem powered ( twin engine ) scrapers are good for jobs having adverse for jobs having adverse grades and poor footing. Owning and operating cost are about 25% higher. CONFIGURATIONS Push-Pull CONFIGURATIONS Push-Pull scrapers can work as a team or can operate individually with a pusher. Tire wear will increase in rock or abrasive materials because of more slippage from the four-wheel drive action.
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
11/27/2008 4 CONFIGURATIONS Auger Auger CONFIGURATIONS Auger CONFIGURATIONS Auger scrapers can self- load in difficult conditions, laminated rock or granular materials. The auger adds weight to the scraper during travel and it is more costly to own and operate than a conventional scraper.
Background image of page 4
11/27/2008 5 BOWL The load-carrying part of a scraper. ejector WORK CYCLE LOAD DUMP HAUL RETURN CUTTING AND LOADING For maximum production both single- and tandem- engine scrapers need the assistance of a push tractor. CUTTING AND LOADING Ejector Dirt enters horizontally and rolls back to fill corners. Curved ejector top keeps load “boiling” to heap high.
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
11/27/2008 6 HAULING Apron lowered to capture the material. Keeping the bowl low enhances stability. SPREADING THE LOAD Dumping and spreading is one continuous operation. SCRAPER SELECTION Three main factors: Job size, volume of material to move and maneuver room Scraper configuration Job conditions, grades, rolling resistance and material type SCRAPER SELECTION COST: Must consider all hourly Must consider all hourly costs for the entire pusher-scraper fleet.
Background image of page 6
11/27/2008 7 ECONOMIC ZONES OF APPLICATION HAUL DISTANCE PERFORMANCE CHART PRODUCTION ESTIMATING STEP 1: WEIGHT - three parts: EMPTY VEHICLE WEIGHT (EVW) LOAD WEIGHT GROSS VEHICLE WEIGHT (GVW) Use the manufacturers data for EVW. Careful about notes concerning what is included.
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
11/27/2008 8 LOAD WEIGHT LOAD WEIGHT is a function of the load volume and the unit weight of the material bi h ld being hauled.
Background image of page 8
Image of page 9
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 01/07/2012 for the course CM 335 taught by Professor Staff during the Fall '08 term at BYU.

Page1 / 23

CPEM Chapter - SCRAPERS The Fresno Scraper Invented in 1883 A NATIONAL HISTORIC MECHANICAL ENGINEERING LANDMARK www.asme.org/history/brochures/h158

This preview shows document pages 1 - 9. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online