Fig. 65.
Assuming good management and a competent crew, the daily output of a steam shovel depends mostly upon the nature of the material excavated; it is also somewhat dependent upon the height and width of the face of the cutting, and largely upon the facilities for disposing of the loaded material, and keeping the machine almost constantly at work by an ample supply of empty cars and wagons. Although these varying conditions differ on each piece of work, the probable output of a machine for a given excavation can be closely estimated by good judgment based on previous experience with similar work. The average daily output in different kinds of materials, and under average, favorable and unfavorable conditions, as described above, is shown in Table II.:
TABLE II.
| Capacity | Delay. | Sand. | Loose gravel. | Dry loam. | Dry clay. | Damp clay. | |
| of dipper. | hours.[2] | Cu. yds. | Cu. yds. | Cu. yds. | Cu. yds. | Cu. yds. | |
| 2½ cu. yds. | 1 | Good | 2,400 | 2,400 | 2,000 | 1,800 | 1,200 |
| " | 5 | Poor | 1,200 | 1,200 | 1,000 | 900 | 600 |
| " | 2½ | Avg. | 1,800 | 1,800 | 1,500 | 1,350 | 900 |
| 1¾ cu. yds. | 1 | Good | 1,600 | 1,600 | 1,200 | 1,000 | 800 |
| " | 5 | Poor | 800 | 800 | 600 | 500 | 400 |
| " | 2½ | Avg. | 1,200 | 1,200 | 900 | 750 | 600 |
| 1 cu. yd. | 1 | Good | 1,000 | 1,000 | 800 | 700 | 500 |
| " | 5 | Poor | 500 | 500 | 400 | 350 | 250 |
| " | 2½ | Avg. | 750 | 750 | 600 | 525 | 375 |
[2] The delay in hours is the time lost in moving forward and waiting for empty cars.
TABLE II.—Continued.
| <————— Loosened by explosives.———> | |||||||
| Stiff blue | Hard | Mixed clay | Loose | Cemented | |||
| Capacity | Delay. | clay. | pan. | and boulders. | rock. | gravel. | |
| of dipper. | hours.[3] | Cu. yds. | Cu. yds. | Cu. yds. | Cu. yds. | Cu. yds. | |
| 2½ cu. yds. | 1 | Good | 800 | 600 | 600 | 600 | 600 |
| " | 5 | Poor | 400 | 300 | 300 | 300 | 300 |
| " | 2½ | Avg. | 600 | 450 | 450 | 450 | 450 |
| 1¾ cu. yds. | 1 | Good | 600 | 400 | 400 | 400 | 400 |
| " | 5 | Poor | 300 | 200 | 200 | 200 | 200 |
| " | 2½ | Avg. | 450 | 300 | 300 | 300 | 300 |
| 1 cu. yd. | 1 | Good | 400 | 300 | 300 | 300 | 300 |
| " | 5 | Poor | 200 | 150 | 150 | 150 | 150 |
| " | 2½ | Avg. | 300 | 225 | 225 | 225 | 225 |
[3] The delay in hours is the time lost in moving forward and waiting for empty cars.
Part III.—Disposition of Material.
Loading the Material for Transportation.—The material excavated by a steam shovel is loaded on cars, wagons or carts. On railway work it is usually loaded on dump or flat cars. On other construction work small dump cars are most generally used, and sometimes wagons or carts.