44 BULLETIN 300, U. S. DEPARTMENT OF AGRICULTURE. 
the bucket from 10 to 30 feet beyond the end of the boom, depending 
on the size of the machine and operating conditions; yet usually this 
should not be considered in determining the required size of a 
machine, but left as a factor of safety, to be used only when neces- 
sary. 
In operating dry-land excavators in timbered country it is often 
necessary to cut stumps flush with the ground, so that the machines 
can travel over them. For this purpose power-operated stump saws 
have been developed and are being used quite extensively by con- 
tractors. The saws are of two types—the circular-band saw and the 
crosscut saw. A power-operated saw of either type costs about $400, 
THE DRY-LAND DIPPER DREDGE. 
DESCRIPTION. 
This machine embodies the same digging principles as the floating 
dipper dredge, but has a great advantage in that it can be assembled 
and dismantled very quickly. The machine can work either up- 
stream or downstream, but it is preferable to operate upstream. The 
machine is made of steel, with either the walking device (Pl. VII, 
Fig. 2), which requires no tracking, or with the track equipment 
(Pl. IX, Fig. 1) in varying widths of span. The dredge is built in 
two sizes, one-half cubic yard and 1 cubic yard. Either type of 
mounting requires a 20-horsepower engine for the one-half-yard 
machine and a 30-horsepower engine for the l-yard dredge. Table 
19 gives the principal data in regard to the machine. 
TABLE 19.—Weights and limiting dimensions of dry-land dipper dredges. 
| Size of shoes for 
| Depth it Truck mounted. Walking. walking device. 
Capac- iT aie 
ity of | 4 one Span. 
dipper-| surtace. daneth. | weignt. | Lensth. | Weient. | Corner. | Middle. 
Cu.yds.| Feet. Feet. Feet. | Pounds. Feet. | Pounds, Feet. Feet. 
4 12 14 24 33;(000 "| 5s.5 scosc eGo ae eae oe eee 
12 1 Se SR Pe Sel ea Geta 26 43, 000 4x5 5x10 
12 18 | 26 to 30 35, 500 30 45, 500 4x5 5X10 
i 14 a el ee eas) iar eae 36 66, 400 5X6 5X10 
14 29 36: "52.000... 5 | eee 
14 25):| ae a | Se eee 40 68, 900 5X6 5X10 
14 BG le pees Sloman < 40 70, 500 5X6 5X10 
14 Ya jill Brags, eee | ee eased Sareea 45 73, 000 5X6 5x10 
14 45 45 60000) |). cscee a ee ee eee 
14 | 50 to 60 50 | Dect eee eee cae ber syare oars Ae SOE So | Beate toes 
The truck-mounted dredges in firm earth will dig a ditch 5 feet 
narrower than the span. In the walking type the span is the dis- 
tance between the inside edges of the shoes. 
The maximum clearance under the dipper when dumping varies 
somewhat according to the length of the boom. A 1-yard dredge 
with a 36-foot boom has a clearance of 11 feet, a dredge with a 40-foot 
ve akc alee aah ae, he, 
