EXCAVATING MACHINERY USED IN LAND DRAINAGE. 31 
staggered, while the ends of the bottom timbers are placed even. The 
staggered ends make possible a more rigid connection and also provide 
means of taking curves while still preserving a solid bearing for the 
rollers. The rigging to pick up the track sections consists of 3-inch 
chain, two pieces 3 feet 9 inches long and two pieces 3 feet 3 inches 
long. With uneven chain lengths one end of the track section is 
held higher than the other, which lightens the labor in making 
track connections. It is asserted that a section can be swung ahead 
and placed in one and one-half minutes. With this type of track 
a contractor has moved his machine 2,600 feet in 10 hours. 
Heavy Hook from lx 18" St. 
S Eh«-100't0 end of Cable 
% hi SEL OO LLL FY 
Bucket —> 
y_-3 Jinks I'chain . 
5 I- 4° Ring 
~2- 33 Rings 
,~/ long and / short. 
-4°Ring-- vA 
eu) a: i chain in each ring 
2 33 Rings -* 
p= ay SNANR PZ/7000 1 NOON 
Machine should go in this direction ----»> nee 4 
J"U- Bolt, 74xX/3 Machine Bolts (countersunk heads) 
‘ ) 
eS Ze 
——e ee i< [ae ES ee 
» 
5 
SS —___— 
= — 
SSS SS SSS 
= — 
iJ Ld i 
NX 
“s~- Ends of bottom planks are shown by dotted lines —” ee ; 
Top Timber 5°x16'x 20'0" Heart Pine. Bottom Timbers 23x/6x20'0'Heart Pine 
Cross Ties 6x8'x 8'0" Sta &.P.Ties 
Fic. 1.—Sectional track for a rotary-scraper excavator with skid and roller mounting. 
A drag-line excavator mounted on skids and rollers moves ahead 
by pulling on the bucket left partly filled in the earth to be excavated, 
the anchor blocks in front of the machine having been previously 
removed. ‘There are instances where the surface material may be 
so soft as to preclude this method unless the top material is first 
excavated down to a stiff subsoil. To avoid this extra labor it is 
possible, after swinging the machine through 180°, to hitch the 
bucket to a cable run through the bed of the machine and anchored 
to the track, and thus to move the machine by backing it up. The 
weight on the track of the machine that is being moved will ordinarily 
furnish sufficient anchorage. This method has been used successfully 
