SHOVELS

SHOVELS

اسلاید 1: SHOVELS

اسلاید 2: SHOVELSWilliam S. Otis, of the firm of Carmichael, Fairbanks and Otis, when living in Canton, Massachusetts in 1834 and 1835, while his firm was performing grading work for the Boston & Providence Railroad built the first steam excavator – a steam shovel.

اسلاید 3: OTIS SHOVEL

اسلاید 4: AN EARLY SHOVEL

اسلاید 5: SHOVELSFront shovels are used predominately for hard digging above track level and for loading haul units. Loading of shot rock would be a typical application.

اسلاید 6: STEP 1: BUCKET SIZEShovels can usually be equipped with different size buckets. Bottom dump buckets are also available.

اسلاید 7: STEP 1: BUCKET SIZEBuckets are rated in both heaped and struck capacities.Both PCSA and SAE use a 1:1 angle of repose for evaluating heaped bucket capacity. CECE specifies a 2:1 angle of repose. Heaped Capacity is the rating of interest for Production Estimating.

اسلاید 8: STEP 2: FILL FACTORThe Fill Factor adjusts Heaped Capacity in lcy based on the type of material being handled.Table 9.1, page 258

اسلاید 9: STEP 2: FILL FACTOR HEAPED BUCKET CAPACITY  FILL FACTOR= VOLUME (lcy)

اسلاید 10: STEP 3: CYCLE TIMEThere are four elements in the production cycle of a shovel:Load bucketSwing with loadDump loadReturn swingSee page 260

اسلاید 11: STEP 3: CYCLE TIMEHeight of cut affects shovel production. Optimum height of cut ranges from 30 to 50% of maximum digging height, with the lower percentage being representative of easy-to-load materials, such as loam, sand, or gravel. Table 9.2

اسلاید 12: STEP 3: CYCLE TIMEAngle of swing affects shovel production. If the angle of swing is increased, the time for a cycle will be increased, whereas if the angle of swing is decreased, the time for a cycle will be decreased. Table 9.2

اسلاید 13: STEP 3: CYCLE TIMEIdeal production of a shovel is based on operating at a 90° swing and optimum height of cut. The effect of the angle of swing on the production of a shovel is illustrated in Table 9.2.

اسلاید 14: STEP 4: EFFICIENCY FACTORWhen selecting a minutes per hour efficiency factor visualize the work site and consider: Materials being handled, bank or broken Size of the shovels’s dumping target, (large or small)

اسلاید 15: STEP 5: CLASS of MATERIALProduction will be in lcy, will need swell factor to adjust to bcy. TABLE 4.3

اسلاید 16: STEP 6: PRODUCTION X Heaped Capacity (lcy) X Fill Factor X height/swing factor = Production (lcy/hr)

اسلاید 17: OTIS STEAM SHOVEL