Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 7 Dozers

DOZERS

Crawler (tracklaying) dozers are the work horses of the construction industry.

DOZERS An advantage of a wheel- type dozer as compared with a crawler dozer is higher speed.

DOZERS They are designed to provide high drawbar pull and tractive effort. The crawler dozer exerts low ground-bearing pressure adding to its versatility.

DOZERS Dozers, tractors equipped with a blade are standard equipment for excavating.

DOZERS Dozers, tractors equipped with a blade are standard equipment for excavating.

DOZERS Dozers, equipped with special clearing blades are used for land clearing.

DOZERS Dozers, equipped with push blades are used for assisting scrapers to load.

DOZERS A dozer, can have a rear mounted ripper for loosing and breaking up rock. Shank

BLADE ADJUSTMENTS Tilting

BLADE ADJUSTMENTS C- frame blade mount, Outside of the tracks

BLADE ADJUSTMENTS C- frame blade mount Inside the tracks

BLADE ADJUSTMENTS Angle

BLADE ADJUSTMENTS Angle

BLADE ADJUSTMENTS Pitch

DOZER PRODUCTION ESTIMATES Step 1. Ideal production Manufacture's charts or Text Fig & 14 Step 2. Grade correction Text Table 7.2, p. 192 Step 3. Material-weight correction

Step 4. Operator skill, GPS and computer graphics DOZER PRODUCTION ESTIMATES

Step 5. Material-type correction DOZER PRODUCTION ESTIMATES Step 6. Operating technique

Table 7.2, page 192 Step 7. Visibility Step 8. Efficiency factor DOZER PRODUCTION ESTIMATES

Step 9. Calculate production Production (lcy) = Ideal Production X product of factors DOZER PRODUCTION ESTIMATES

Step 10. Material conversion if required Table 4.3, page 99 Step 11. Determine total operating hours required DOZER PRODUCTION ESTIMATES

DOZER PRODUCTION Ideal production Ideal production values (lcy/hr) are based on the following conditions: u 100% efficiency u Power-shift machines

DOZER PRODUCTION Ideal production uDozer cuts 50 ft, then drifts the blade load to dump over a high wall

DOZER PRODUCTION Ideal production Ideal production values (lcy/hr) are based on the following conditions: u Coefficient of traction  0.5 crawler machines  0.4 wheel machines

DOZER PRODUCTION Ideal production NO Based on: u Hydraulic controlled blades YES

DOZER PRODUCTION Material-weight correction Ideal production values are based on a soil density of 2,300 lb/LCY. Material-weight correct = 2,300/lcy (standard) Actual material unit wt.

DOZER PRODUCTION Material-type correction See Fig. 7.11, p. 186 Sandy Clay Table 7.2, page 192

DOZER PRODUCTION Efficiency factor Ideal production is based on a 60-minute working hour. Efficiency factor =

DOZER PRODUCTION Exercise 1 How long will it take a crawler D7G dozer w/ straight blade to move 6,700 bcy’s 150 feet? Grade -2% Dry clay, 1,950 lb/lcy Operator of average skill 50-min hour

Exercise 1 Step 1. Ideal production, D7G dozer w/ straight 150 ft. Find the dozing distance on the bottom horizontal scale. Read up vertically and intersect the production curve for the D7G. Read production on the left vertical scale. Fig. 7.13, page 190

Step 1. Ideal production, 150 ft. 320 lcy/hr

Exercise 1 Step 2. Grade Correction, for -2% (-) downgrade or (+) upgrade Find the % grade on the bottom horizontal scale. Read up vertically and intersect the curve. Read the correction on the left vertical scale. Table 7.2, page

Exercise 1 Step 3. Material-weight correction, for 1,950 lb/LCY Ideal production values are based on a soil density of 2,300 lb/lcy. Material-weight correct = 2,300 lb/lcy 1,950 lb/lcy  1.18

Exercise 1 Step 4. Operator skill, Average, track-type tractor Table 7.2, page 192 Operator skill = 0.75

Exercise 1 Step 5. Material-type correction, Dry clay Table 7.2, page 192 Material-type correction = 1.00

Exercise 1 Step 6. Operating technique, Not specified Table 7.2, page 192 Operating technique = 1.00

Exercise 1 Step 7. Visibility, Not specified, assume satisfactory Table 7.2, p. 192 Visibility = 1.00

Exercise 1 Step 8. Efficiency factor, 50-min hour Table 7.2, p. 192 Efficiency factor =  0.83

Exercise 1 Step 9. Calculate Production Product of factors  Grade Weight Operator Technique Material Eff. Visibility

Exercise 1 Step 9. Calculate Production Production (lcy) = 320 lcy/hr X  252  250 lcy/hr

Exercise 1 Step 10. Material conversion, Dry clay, lcy to bcy Table 4.3, page 99 Swell factor 0.74 Production (bcy) = 250 lcy/hr X 0.74  185 bcy/hr

Exercise 1 Step 11. Operating Hours, to move 6,700 bcy’s 6,700 bcy 185 bcy/hr = 36.2 hr

THE FUTURE