38 BULLETIN 300, U. S. DEPARTMENT OF AGRICULTURE. 
cable-swing machines in that when a swing of 180 degrees is re- 
quired the machine can complete the full circle and return to the 
loading point, whereas the cable-swing machine must be reversed 
with loss of both time and energy. 
A 38-yard, walking, drag-line excavator having an 80-foot boom 
was used to build a levee averaging 15 feet high. The machine 
traveled on the berm, taking dirt from the borrow pit, which dia 
not exceed 10 feet in depth, and depositing the material on the levee 
site. The angle of swing was about 145 degrees. To fill the bucket » 
required 30 seconds; to hoist, swing, and dump took 25 seconds; and 
30 seconds were required to return to the borrow pit. The entire 
operation thus consumed 85 seconds. In the excavation of a ditch 
36 feet deep in which the angle of swing was 90 degrees and the 
distance of hoist 60 feet, a 2-yard machine with a 75-foot boom was 
used. Filling the bucket required 25 seconds; to hoist, swing, and 
dump required 20 seconds; and to return to fill the bucket consumed 
20 seconds. Thus the entire time of one operation was 65 seconds. 
The output of drag-line excavators of various sizes will vary 
greatly with the length of boom, depth of cut, angle of swing, and 
character of digging. The figures given in Table 15 will serve as an 
approximate guide. 
TABLE 15—Output of drag-line excavators. 
E Output 
bucket.| of boom. job. double 
shift. 
Cu. yds Feet. | Cubic yards.| Cubic yards. 
1 40 250, 000 8, 000 
ips 50 300, 000 25, 000 
2 60 400, 000 30, 000 
23 65 500, 000 35, 000 
3 70 800, 000 40, 000 
33 80 | 1,000, 000 50, 000 
43 100 | 1,509, 009 70, 000 
1 By economical size of job is meant the yardage below which the machine can not be installed and 
operated without appreciably increasing the cost per cubic yard of excavation. 
These figures give only the average output, including all lost time; 
they may be greatly exceeded in any particular month during con- 
tinuous operation. On one contract a 2-yard, 60-foot-boom drag- 
line excavator averaged 70,000 cubic. yards a month with double 
shift while building a levee containing 1,100 cubic yards per station. 
In the excavation of quicksand great care must be used in handling 
the bucket. The hoisting line is kept taut, holding the back end 
of the bucket a foot or so above the sand, while the cutting edge, or 
lip of the bucket, is pulled into the material. The output of a ma- 
chine in quicksand is about one-fourth that in ordinary earth. 
