Table of Contents
Chapter 4

— David Wagner 2007/06/29 15:40

Problem 1.

JpGraph Table Data Plot

0.9 min

Problem 2.

Load:10 LCY, Cycle Time: 0.15 min, Distance: 95', Haul Time: {95*60}/{1.5*5280}=0.72 min, Return Time: 95/{5*528}=0.22 min, Cycle Time: 0.15+0.72+0.22=1.09 min,

Productivity: {10*60*0.83}/{1.09}=457

457 LCY/hr

Problem 3.

N=5<5.2 → eq. 4-17: P={5/5.2}*300*0.8=231 BCY/hr, Unit Cost: {40+5*20}/{251}=0.61

$0.61/BCY

Problem 4.

Grade: 3+{100/20}=8%

Total Resistance: 0.08*163900=13112 lb

Regular Pull: 13112/{1-0.1}=14569 lb [fig 4-2]→ 9 mph

9 mph

Problem 5.

BFF[tnl 3-2]:0.95; BV=4*0.95=3.8 LCY; Basic Cycle Time [tbl 4-6]: 0.35 min; Effective grade: 120/20=6%; Total Time [fig 4-15]=0.5 min

Productivity: 3.8*50/0.85=224 LCY/hr; time=3000/224=13.4 hr

13.4 hr

Problem 6.

EG= 5 + 120/20 = 11%; Loaded Time: [fig 4-4] 6.2 min

EG = -5 + 120/20 = 1%; Empty Time: [fig 4-6] 1.7 min

7.9 min

Problem 7.

Load Time: {12/300}*60=2.4 min

a. N={8+2+2.4}/{2 4} =5.2 approx6 Trucks

b. 300*0.8=240 BCY

c. Unit Cost: {40+6*20}/{240}=$0.67 /BCY

Problem 8.

  • Traction Coefficient[tbl. 4-2]: 0.60
  • Maximum Usable Pull: 0.6*38720=23232 lb
  • Grade Resistance: 70400G
  • Rolling Resistance: {100*70400}/2000=3520 lb

Total Resistance: 70400*G + 3520=23232 right G=0.28

28% Grade

Problem 9.

Pull scrapers pick up dirt in one or more pans when pulled by a tractor. They can be used for adverse soil conditions when towed by a tractor with high-flotation tires, and can be loaded without pusher assistance in sandy and sandy-clay soils. Though relatively inexpensive, they can be very productive on medium hauls in suitable soils.

Discussion


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