EXCAVATING MACHINERY USED IN LAND DRAINAGE. 45 
boom a clearance of 13 feet. The height of the A frame on the stand- 
ard 1-yard dredge is 19 feet. On wide-span dredges carrying 50 to 55 
foot booms the A frame is 21 feet high. Four men can set up either 
size of the track machine in three days and easily dismantle it in 13 
days. The track machine requires three men for operation—one run- 
ner and two trackmen. The one-half-yard dipper is 30 inches wide 
and 25 inches deep, while the 1-yard dipper is 41 mches wide and 33 
mehes deep. 
Five men can assemble the walking type in four days and disman- 
tle it in one and one-half to two days. The 1-yard machine with a 40- 
foot boom when dismantled will make 12 wagonloads, the heaviest 
loads being the engine and the boom. Only two men are required 
to operate the walking dredge—one runner and one helper. The 
1-yard machine will consume 25 gallons of kerosene per shift of 10 
hours. About 1 gallon of black oil and 2 quarts of lubricating oil are 
required per shift. <A hoisting cable will ordinarily dig 30,000 yards 
before being discarded. Ordinarily five-eighths inch cable is used for 
the hoisting, swinging, and backing lines. An extension is provided 
for the regular dipper handle which will enable the dredge to dig 
greater depths. | 
The average bearing pressure for the walking dredge is about 4 
pounds per square inch, so the dredge can easily pass over ground on 
which animals would mire. The walking speed of the dredge is from 
500 to 800 feet an hour. The machine can walk only in one direction. 
It is possible, however, to change the mechanism so it may walk back- 
ward. The ability to walk either forward or backward without re- 
quiring extensive alterations would add to the adaptability of the 
machine. 
The walking dredge will excavate more material than a track ma- 
chine of the same size, as it moves ahead more quickly. Thus on jobs 
of considerable size the walking device would easily pay for itself. 
One advantage of this type is that the machine can walk across rail- 
road tracks, which eliminates removing bridges. The walker can also 
turn square corners. The 1l-yard walking machine will excavate on 
an average, including all delays, about 500 cubic yards per shift of 10 
hours; on steady runs this output will be greatly exceeded. Either 
size of dredge can be shipped on one car. 
For night work many operators equip these machines with the com- 
bination generator and storage-battery hghting outfit; if the gen- 
erator becomes disabled the storage batteries will carry the lights for 
the rest of the night shift. 
On account of the low assembling costs for this type of machine, 
it can handle economically jobs of small yardage. The walking 
dredge at each move covers from 5 to 10 feet and will walk from 
