Based on the scraper specifications in Table $8\mathrm{.}1$ and the performance charts in Figs. $8\mathrm{.}7$ and $8\mathrm{.}8,$ and for haul conditions as stated here, analyze the probable scraper production. How many scrapers should be used and what will be the production in bcy per hour? The material to be hauled is cohesive. It has a swell factor of $0\mathrm{.}77$ and a unit weight of $2,940$ lb$/$bcy$.$ The expected rolling resistance for the well$-$maintained haul road is $+4\%.$ Assume a $0\mathrm{.}85-$min load time will yield an average load of $89\%$ of heaped capacity. To account for both acceleration and deceleration, use an average speed of $5$ mph over a distance of $200$ ft$.$ Use a $45-$min hour efficiency factor. The total length of haul is $3,000$ ft and has the following individual segments when moving from cut to fill: Gross weight

$1$st gear torque converter drive

$6$th gear direct drive

$2$nd gear torque converter drive

$7$th gear direct drive

$3$rd gear direct drive

$8$th gear direct drive

$4$th gear direct drive

E$.$ Empty $43,945kg(96,880lb)$

$5$ th gear direct drive

L$.$ Loaded $77,965kg(171,880$ lb$)$ Figure $8\mathrm{.}8$ Retarding performance chart for a Caterpillar $631$E scraper. Reprinted courtesy of Caterpillar, Inc.

Interactive Graph

Gross weight

$3.3$rd gear direct drive

$4.4$th gear direct drive

$5.5$ th gear direct drive

$6.6$th gear direct drive

$7.7$th gear direct drive

$8.8$th gear direct drive

E$.$ Empty $43,945kg(96,880lb)$

L$.$ Loaded $77,965kg(171,880lb)$

$600$ ft $5\%$ grade

$2,200$ ft $2\%$ grade

$200$ ft $4\%$ gradeTable $8\mathrm{.}1$ Specifications for a Caterpillar $631$E Scraper

$\backslash$table$[[,$Engine: flywheel power $450,],[,$Transmission: semiautomatic power shift, eight speeds,,$],[$Capacity of scraper:,Struck,,$21$ cy$],[$Weaped$,$Empty,Drive axle,$31$ cy$],[$Weight distribution:,,Rear axle,$67\%],[,$Loaded,Drive axle,$53\%],[$Operating weight:,,Rear axle,$47\%],[$Rated load:,Empty,,$96,880$lb$*],[$Top speed:,,,$75,000$lb$]]$

$*$Includes coolant, lubricants, full fuel tank, rollover protective system $($ROPS$)$ canopy, and operator