Power shovel1

Power Shovel

1. POWER SHOVEL

2. A power shovel is a bucket-equipped machine, usually electrically powered, used for digging and loading earth or fragmented rock and for mineral extraction. The power shovel is most useful where there is considerable hard digging or consolidated material from a bank that will stand with a fairly face POWER SHOVEL

3. Shovels normally consist of a revolving deck with a power plant, driving and controlling mechanisms, usually a counterweight, and a front attachment, such as a crane (" boom ") which supports a handle (" dipper " or "dipper stick") with a digger (" bucket ") at the end. "Dipper" is also sometimes used to refer to the handle and digger combined. The machinery is mounted on a base platform with tracks or wheels. Modern bucket capacities range from 8 m3 to nearly 80 m3. Design

4. LINE DIAGRAM

5. It may be mounted on crawler trucks and rubber tired wheels. But power shovels mounted on rubber tired wheels have high speed w.r.t crawler mounted units. A crawler-mounted shovel is well suited for rock quarry work because of its ruggedness, power, and stability.

6. The shovel operates using several main motions: hoist - pulling the bucket up through the bank (i.e. the bank of material being dug) crowd - moving the dipper handle out or in to control the depth of cut and when positioning to dump swing - rotating the shovel between digging and dumping propel - moving the shovel unit to different locations or dig positions Operation

7. A shovel's work cycle, or digging cycle, consists of four phases : digging swinging dumping Returning The digging phase consists of crowding the dipper into the bank, hoisting the dipper to fill it, then retracting the full dipper from the bank. The swinging phase occurs once the dipper is clear of the bank both vertically and horizontally. The operator controls the dipper through a planned swing path and dump height until it is suitably positioned over the haul unit (e.g. truck). Dumping involves opening the dipper door to dump the load, while maintaining the correct dump height. Returning is when the dipper swings back to the bank, and involves lowering the dipper into the tuck position to close the dipper door.

8. CLASSIFICATION

9. A front shovels bucket excavates in upward direction. It develops excavation breakout force by crowding material away from the machine. It is used to excavate about the earth surface. FRONT SHOVEL

10. FRONT SHOVEL

11. FRONT SHOVEL

12. A backhoe is in the form of a downward are unit. It develops exaction breakout force by pulling the bucket toward the machine and curling the bucket inward. It is used to excavate below the earth surface . BACK HOE

13. BACK HOE

14. BACK HOE

15. SIZE OF A POWER SHOVEL The size of a power shovel is indicated by the size of the bucket, expressed in cubic yards. Power shovels are commonly available in the following sizes: 3/8, 0.5, 0.75, 1, 1.25, 1.5, 2 and 2.5 cub. Yds.  

16. Selection of type and size of power shovel Job location Wheel mounted power shovel Crawler mounted power shovel Cost of per cum of output Size of job Cost of transporting Depreciation cost Downtime cost Cost of wage Combined cost of drilling, blasting and excavating of rocks

17. Job conditions High lifts needs longer reach Bigger blasted rocks Hard and tough material Completion time of project Size of hauling units Weight limitations and clearances on highways bridges etc.

18. Output of power shovel (m 3 /hr) = q*(3600/cycle time in seconds)*efficiency q(m 3 /hr) = heaped capacity*swell factor*bucket factor Output

19. Class of material Depth of cut Angle of swing Job conditions Size of hauling units Management conditions maintenance Skill of operator Physical condition of the shovel Factors affecting the output of power shovel

20. 1. Embankment Digging 2. Loading into Haul Units 3. Side Casting 4. Dressing Slopes 5. Dumping on Soil Banks 6. Digging Shallow Trenches   APPLICATIONS

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