Chp_8_Scrapers_8th_ed MOD P 2

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PRODUCTION ESTIMATING:

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.

LOAD WEIGHT:

LOAD WEIGHT LOAD WEIGHT is a function of the load volume and the unit weight of the material being hauled. The scraper volume is in lcy’s. Use a LOOSE VOLUME unit weight or convert the volume to match the units of the weight.

EMPTY AND GROSS WEIGHT:

EMPTY AND GROSS WEIGHT The EVW of our scraper is 96,880 lb. It will carry a 24.3 bcy Load. The material, a clay, has a unit weight of 3,100 lb/bcy STEP 1: EVW ( see Figure 8.10 data ) 96,880 LOAD WT (24.3 X 3100) = 75,330 GVW 172,210

PRODUCTION ESTIMATING:

PRODUCTION ESTIMATING STEP 2: ROLLING RESISTANCE (RR) See TABLE 6.1 for ROLLING RESISTANCE VALUES.

PRODUCTION ESTIMATING:

PRODUCTION ESTIMATING STEP 2: ROLLING RESISTANCE (%) ROLLING RESISTANCE (RR) can be expressed either as a (%) or in (lb/tn).

PRODUCTION ESTIMATING:

PRODUCTION ESTIMATING STEP 2: ROLLING RESISTANCE (lb) for a loaded scraper for an empty scraper TP = tire penetration in inches

PRODUCTION ESTIMATING:

PRODUCTION ESTIMATING STEP 3: GRADE RESISTANCE (GR) or ASSISTANCE ( GA ) (%) Haul The grade (%) of the haul road from the Excavation to the Dump area. Return The grade (%) of the haul road from the Dump to the Excavation area.

PRODUCTION ESTIMATING:

PRODUCTION ESTIMATING STEP 3: GRADE RESISTANCE or ASSISTANCE (lb/tn) Haul Return

PRODUCTION ESTIMATING:

PRODUCTION ESTIMATING STEP 4: TOTAL RESISTANCE (TR) (%) Haul RR HAUL ( % ) + GR HAUL ( % )= TR HAUL ( % ) Return RR RETURN ( % ) + GR RETURN ( % ) = TR RETURN ( % )

PRODUCTION ESTIMATING:

PRODUCTION ESTIMATING STEP 4: TOTAL RESISTANCE EXPRESSED AS RIMPULL REQUIRED (lb) Haul RR HAUL (lb) + GR HAUL (lb)= RP HAUL (lb) Return RR RETURN (lb) + GR RETURN (lb)= RP RETURN (lb)

PRODUCTION ESTIMATING:

PRODUCTION ESTIMATING STEP 5: TRAVEL SPEED HAUL and RETURN PERFORMANCE or RETARDER Chart ( Figures 8.10 & 8.11 ). Performance chart for POSITIVE TOTAL RESISTANCE. Retarded chart for NEGATIVE TOTAL RESISTANCE

PRODUCTION ESTIMATING:

PRODUCTION ESTIMATING STEP 6: TRAVEL TIME HAUL AND RETURN (min)

PRODUCTION ESTIMATING:

PRODUCTION ESTIMATING

PRODUCTION ESTIMATING:

PRODUCTION ESTIMATING STEP 7: LOAD TIME With the proper size push-tractor a good average load time for a scraper is 0.85 min. STEP 8: DUMP TIME See Table 8.7

PRODUCTION ESTIMATING:

PRODUCTION ESTIMATING STEP 7 LOAD TIME STEP 8 DUMP TIME

PRODUCTION ESTIMATING:

PRODUCTION ESTIMATING STEP 9: TURN TIME @ DUMP Average turn time at the fill is 0.21 min. TURN TIME @ CUT Average turn time in the cut is 0.30 min. STEP 10: TOTAL CYCLE TIME

PRODUCTION ESTIMATING:

PRODUCTION ESTIMATING STEP 7 LOAD TIME STEP 8 DUMP TIME STEP 9 TURN TIME @ DUMP STEP 9 TURN TIME @ FILL STEP 10 TOTAL TIME

PRODUCTION ESTIMATING:

PRODUCTION ESTIMATING STEP 11: PUSHER TIME = (1.4 X Load Time) + 0.25 STEP 12: BALANCED FLEET

PRODUCTION ESTIMATING:

PRODUCTION ESTIMATING STEP 13: EFFICIENCY FACTOR STEP 14: PRODUCTION If the number of scrapers is less than the balance Number calculated in STEP 12 the scrapers control production. .

PRODUCTION ESTIMATING:

PRODUCTION ESTIMATING STEP 14: PRODUCTION If the number of scrapers is GREATER than the balance Number calculated in STEP 12 the pusher will control production. .

PRACTICAL EXERCISE:

PRACTICAL EXERCISE Given the following conditions what is the maximum scraper production? Use chap. 8 Performance charts One push tractor 50 min-hour efficiency Dry clay

PRACTICAL EXERCISE:

PRACTICAL EXERCISE RR is 40 lb/tn The scraper load will be 28.3 lcy Haul is 3,200 ft long 600 ft @ +3 % and 2,600 ft @ -6 % Acceleration/deceleration for 200ft @ 5mph at each end of haul and return

EMPTY AND GROSS WEIGHT:

EMPTY AND GROSS WEIGHT STEP 1: Scraper EVW is 96,880 lb. Fig. 8.10 The scraper load is 28.3 lcy Dry clay Dry clay 2,700 lb/BCY Table 4.3

EMPTY AND GROSS WEIGHT:

EMPTY AND GROSS WEIGHT STEP 1: The scraper load is 28.3 lcy Load Volume in bank measure? Swell factor (dry clay) Table 4.4 p.103 28.3 LCY x 0.74 x 1.1 = X bcy Add 10% to swell factors in Table 4.4 for material push-loaded into scraper

EMPTY AND GROSS WEIGHT:

STEP 1: Load Volume in bank measure? Push-loaded scraper (see Volume of a Scraper section) 28.3 LCY x 0.74 x 1.1 = x BCY = 23.0 BCY EMPTY AND GROSS WEIGHT

EMPTY AND GROSS WEIGHT:

EMPTY AND GROSS WEIGHT STEP 1: Dry clay 2,700 lb/BCY Load weight = 23.0 BCY x 2,700lb/BCY  62,100 lb

EMPTY AND GROSS WEIGHT:

EMPTY AND GROSS WEIGHT STEP 1: EVW 96,880 LOAD WT 62,100 GVW 158,980

ROLLING RESISTANCE :

ROLLING RESISTANCE STEP 2: • RR is 40 lb/tn or

GRADE RESISTANCE:

GRADE RESISTANCE STEP 3: • Haul is 3,200 ft long 600ft @ +3 % and 2,600ft @ -6 % Haul 200 ft acceleration 3% 400 ft 3% 2,400 ft -6% 200 ft deceleration -6%

GRADE RESISTANCE:

GRADE RESISTANCE STEP 3: • Haul is 3,200 ft long 600ft @ +3 % and 2,600ft @ -6 % Return 200 ft acceleration 6% 2,400 ft 6% 400 ft -3% 200 ft deceleration -3%

TOTAL RESISTANCE:

TOTAL RESISTANCE STEP 4: TR Haul

TOTAL RESISTANCE:

TOTAL RESISTANCE STEP 4: TR Return

POWER AVAILABLE:

POWER AVAILABLE

POWER AVAILABLE:

POWER AVAILABLE Haul Empty Loaded

POWER AVAILABLE:

Haul POWER AVAILABLE

POWER AVAILABLE:

Haul POWER AVAILABLE

POWER AVAILABLE:

Speed  16 mph Haul POWER AVAILABLE

POWER AVAILABLE:

Speed  17 mph Return POWER AVAILABLE

TRAVEL SPEED:

TRAVEL SPEED STEP 5: Travel Speed Haul

TRAVEL SPEED:

TRAVEL SPEED STEP 5: Travel Speed Return

TRAVEL TIME:

TRAVEL TIME STEP 6: Travel Time Haul

TRAVEL TIME:

TRAVEL TIME STEP 6: Travel Time Haul

TRAVEL TIME:

TRAVEL TIME STEP 6: Travel Time Haul

TRAVEL TIME:

TRAVEL TIME STEP 6: Travel Time Return

TRAVEL TIME:

TRAVEL TIME STEP 6: Travel Time Return

TRAVEL TIME:

TRAVEL TIME STEP 6: Travel Time Return

PRODUCTION ESTIMATE:

PRODUCTION ESTIMATE Table 8.7 Time min Step 6 Haul time 2.01 Step 6 Return time 2.64 Step 7 Load time 0.85 Step 8 Dump time 0.37 Step 9 Turn @ dump 0.21 Step 9 Turn @ cut 0.30 Step 10 Total cycle time 6.38

PUSHER TIME:

PUSHER TIME STEP 11: PUSHER TIME = (1.4 X Load Time) + 0.25 (1.4 X 0.85) + 0.25 = 1.44 min

BALANCED FLEET:

BALANCED FLEET STEP 12: BALANCED FLEET

BALANCED FLEET:

BALANCED FLEET STEP 12: BALANCED FLEET Therefore need to investigate using: 4 scrapers 5 scrapers

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