30 



BULLETIN 300;, U. S. DEPARTMENT OP AGRICULTURE. 



Table 1. — Cost of operation of single-bucket templet excavator on a ditch in Southern 



Louisiana — Continued. 



Month. 



Exca- 

 vation. 



Cost 



per 



cubic 



yard. 



Dis- 

 tance 

 exca- 

 vated. 



Total 

 number 



days 

 worked. 



Actual 

 number 



days 

 digging. 



Average 



length 



dug per 



day. 



Maxi- 

 mum 

 length 

 dug per 

 day. 



Aver- 

 age 

 depth. 



Maxi- 

 mum 

 depth. 





Cvbic 



yards. 



4,175.9 

 10, 559. 



7, 303. 

 10,151.2 

 10,938.5 



Cents, 

 0.076 

 .080 

 .101 

 .077 

 .075 



Feet. 

 1,115 

 1,785 

 1,200 

 1,850 

 1,875 



16 

 30 

 26 

 29 

 27 



9.45 

 18.7 

 10.8 

 18.1 

 16.3 



Feet. 

 120.5 

 95.4 

 111.1 

 102.3 

 115. 03 



Feet. 

 195 

 140 

 114 

 120 

 135 



Feet. 

 3.63 

 5.62 

 5.57 

 5.10 

 5.38 



Feet. 

 5.30 





7.00 





6.70 





5.80 





6.10 







Total or av'g 



43, 127. 6 



.081 



7,825 



128 



73.35 



106. 60 



195 



5.06 



7.00 



THE WHEEL TYPE OF EXCAVATOR. 



The wheel excavator consists of a steel frame mounted on wheels, 

 which supports on the front end an engine and boiler and on the rear 

 end a pivoted steel framework holding the digging wheel, as shown 

 in Plate VII, figure 1. This excavating wheel revolves upon anti- 

 friction wheels placed just outside the rim of the wheel. The exca- 

 vating scoops or buckets are placed on the circumference of this 

 wheel. The front of each scoop is provided with a cutting edge, 

 which slices a thin layer of earth from the trench as the wheel rotates. 

 When the bucket reaches the top of the wheel, the earth falls onto 

 a belt conveyor, which deposits it on the waste bank. The machine 

 can be mounted on caterpillar tractors for use in wet soil. It is 

 built in several sizes, so that ditches with top widths of from 2 J to 

 12 feet and with smooth side slopes can be dug. The cost of the 

 excavator" varies from $4,000 to $12,000, according to the size of 

 ditch it is desired to dig. 



There is a wheel type of trench excavator so designed that by 

 adding side knives sloping sides can be dug. This machine is illus- 

 trated in Plate VII, figure 2. A series of buckets attached to two 

 parallel chains travel over the circumference of a wheel mounted on 

 a frame, which is supported by a central shaft about which the wheel 

 revolves. The cutting knives slice the earth from the sides of the 

 ditch, the dirt falling into the path of the buckets. The excavator 

 is made in two sizes. The smaller size will dig 5 feet deep, 90 inches 

 wide, and any side slope not flatter than 1 to 1. The larger size will 

 dig 6 feet deep and 10 feet wide. The machine may be mounted 

 on caterpillar tractors. For the small size 4 by 6 foot tractors are 

 used, while the large machine requires 4$ by 11 foot tractors. Either 

 steam or gasoline power is furnished. This wheel excavator is suit- 

 able for the construction of small open ditches. It works to the best 

 advantage in a soft, wet soil; under these conditions its average 

 daily output is about 300 cubic yards. 



Experience has shown that it is a mistake for a maker to attempt 

 to build one machine of this type that is suitable for all classes of 



